Spangdahlem F-16 AIB Report Package (JACC).pdf

UNITED STATES AIR FORCE

AIRCRAFT ACCIDENT INVESTIGATION

BOARD REPORT

F-16CM, T/N 91-0366

480TH FIGHTER SQUADRON

52ND FIGHTER WING

SPANGDAHLEM AIR BASE, GERMANY

LOCATION: NEAR GRAFENWOEHR, GERMANY

DATE OF ACCIDENT: 11 AUGUST 2015

BOARD PRESIDENT: COLONEL JILL A. LONG

Conducted IAW Air Force Instruction 51-503

United States Air Force Accident Investigation Board Report

Class A, F-16CM, Spangdahlem Air Base, Germany

Under 10 U.S.C. § 2254(d) the opinion of the accident investigator as to the cause of, or the factors

contributing to, the accident set forth in the accident investigation report, if any, may not be considered as

evidence in any civil or criminal proceeding arising from the accident, nor may such information be

considered an admission of liability of the United States or by any person referred to in those conclusions

or statements.

EXECUTIVE SUMMARY

UNITED STATES AIR FORCE

AIRCRAFT ACCIDENT INVESTIGATION

F-16CM, T/N 91-0366

NEAR GRAFENWOEHR, GERMANY

11 AUGUST 2015

On 11 August 2015, an F-16CM tail number 91-0366, assigned to the 52nd Fighter Wing,

Spangdahlem Air Base, Germany experienced an unrecoverable engine malfunction while on a

local training mission near Grafenwoehr, Germany resulting in pilot ejection and a total loss of the

aircraft. After approximately 29 minutes of flight, the mishap pilot experienced a loss of thrust.

Five attempts were made by the mishap pilot to restart the failed engine. Prior to ejection the

mishap pilot maneuvered the aircraft away from populated areas; ejecting at 156 knots calibrated

air speed and approximately 400 feet above ground level. The mishap pilot sustained minor

injuries. Search and Recovery efforts were facilitated by local German nationals, the German

Bundeswehr, and the US Army. The mishap aircraft was destroyed upon impact; the loss was

valued at $39,796,422.00. Damage to non-US government property consisted of damage to trees,

shrubbery, soil, and crops.

The Accident Investigation Board President determined, by a preponderance of evidence, that the

cause of the mishap was a structural failure of the bearing cage within the lower governor ballhead

bearing. This structural failure caused the main engine control to malfunction, which prohibited

fuel flow to the engine. The lack of fuel flow prevented engine restart and resulted in a complete

loss of thrust, requiring the mishap pilot to eject from the mishap aircraft.

United States Air Force Accident Investigation Board Report

Class A, F-16CM, Spangdahlem Air Base, Germany

F-16CM, T/N 91-0366, 11 August 2015

SUMMARY OF FACTS AND STATEMENT OF OPINION

F-16CM, T/N 91-0366

11 AUGUST 2015

TABLE OF CONTENTS

ACRONYMS AND ABBREVIATIONS ...................................................................................... iii

PSEUDONYMS ............................................................................................................................ vi

SUMMARY OF FACTS ................................................................................................................ 2

1. AUTHORITY AND PURPOSE .................................................................................................2

a. Authority .........................................................................................................................2

b. Purpose ............................................................................................................................2

2. ACCIDENT SUMMARY ...........................................................................................................2

3. BACKGROUND ........................................................................................................................3

a. United States Air Forces in Europe-United States Air Forces Africa (USAFE-

AFAFRICA) ..............................................................................................................3

b. Third Air Force (3 AF) ..................................................................................................3

c. 52nd Fighter Wing (52 FW) ..........................................................................................4

d. 52nd Operations Group (52 OG) ...................................................................................4

e. 480th Fighter Squadron (480 FS) ..................................................................................4

f. F-16 Fighting Falcon......................................................................................................4

4. SEQUENCE OF EVENTS .........................................................................................................4

a. Mission ............................................................................................................................4

b. Planning ..........................................................................................................................5

c. Preflight ...........................................................................................................................5

d. Summary of Accident .....................................................................................................5

e. Impact ..............................................................................................................................7

f. Egress and Aircrew Flight Equipment (AFE) .................................................................7

g. Search and Rescue (SAR) ...............................................................................................8

h. Recovery of Remains ......................................................................................................8

5. MAINTENANCE .......................................................................................................................8

a. Forms Documentation .....................................................................................................8

b. Inspections ......................................................................................................................8

c. Maintenance Procedures .................................................................................................9

d. Maintenance Personnel and Supervision ......................................................................10

e. Fuel, Hydraulic, and Oil Inspection Analyses ..............................................................10

f. Unscheduled Maintenance .............................................................................................11

6. AIRFRAME, MISSILE, OR SPACE VEHICLE SYSTEMS ..................................................11

a. Structures and Systems .................................................................................................11

b. Evaluation and Analysis ..............................................................................................12

(1) Recorded Data ....................................................................................................... 12

(2) Flight Control Surfaces ......................................................................................... 13

(3) Landing Gear ........................................................................................................ 13

United States Air Force Accident Investigation Board Report

Class A, F-16CM, Spangdahlem Air Base, Germany

F-16CM, T/N 91-0366, 11 August 2015

(4) Fuel System ........................................................................................................... 13

(5) Hydraulic System .................................................................................................. 13

(6) Electrical Systems ................................................................................................. 13

(7) Emergency Power System (EPU) ......................................................................... 13

(8) Propulsion Interface .............................................................................................. 13

(9) Engine ................................................................................................................... 14

(10) Escape System ..................................................................................................... 16

7. WEATHER ...............................................................................................................................16

a. Forecast Weather ...........................................................................................................16

b. Observed Weather .........................................................................................................17

c. Space Environment .......................................................................................................17

d. Operations ......................................................................................................................17

8. CREW QUALIFICATIONS .....................................................................................................17

9. MEDICAL ................................................................................................................................18

a. Qualifications ................................................................................................................18

b. Health ............................................................................................................................18

c. Pathology.......................................................................................................................18

d. Lifestyle ........................................................................................................................19

e. Crew Rest and Crew Duty Time ...................................................................................19

10. OPERATIONS AND SUPERVISION ...................................................................................19

a. Operations .....................................................................................................................19

b. Supervision ...................................................................................................................19

11. HUMAN FACTORS ANALYSIS ..........................................................................................19

12. GOVERNING DIRECTIVES AND PUBLICATIONS .........................................................20

a. Publically Available Directives and Publications Relevant to the Mishap ...................20

b. Other Directives and Publications Relevant to the Mishap ..........................................20

c. Known or Suspected Deviations from Directives or Publications ................................20

STATEMENT OF OPINION ....................................................................................................... 21

1. OPINION SUMMARY .............................................................................................................21

2. CAUSE .....................................................................................................................................21

3. CONCLUSION .........................................................................................................................22

INDEX OF TABS ......................................................................................................................... 24

United States Air Force Accident Investigation Board Report

Class A, F-16CM, Spangdahlem Air Base, Germany

F-16CM, T/N 91-0366, 11 August 2015

iii

ACRONYMS AND ABBREVIATIONS

-1Cl Dash 1 checklist

3 AF 3rd Air Force

52 FW 52nd Fighter Wing

52 OG 52nd Operations Group

480 FS 480th

Fighter Squadron

480 OSS 480th Operations Support

Squadron

AAR After Action Report

AB Air Base or Afterburner

AC Alternating Current

ACBT Air Combat Training

ACES II Advanced Concept

Ejection Seat II

AETC Air Education and Training

Command

AF Air Force

AFB Air Force Base

AFC Augmentor Fuel Control

AFE Aircrew Flight Equipment

AFI Air Force Instruction

AFIP Air Force Institute of Pathology

AFLCMC/LPSEBB Air Force Life Cycle

Management Center/F-110

Engineering Section

AFPAM Air Force Pamphlet

AFAFRICA Air Forces in Africa

AFRICOM Africa Command

AFSAS Air Force Safety Automated

System

AFSEC Air Force Safety

Center

AFTO Air Force Technical Order

Ag Silver

AGL Above Ground Level

AHLTA Armed Forces Health

Longitudinal Technology Application

AIB Accident Investigation Board

ALO Air Liaison Officer

AMDS Aerospace Medicine

Squadron

ARMS Aviation Resource Management

System

ATV All-Terrain Vehicle

BSA Basic Surface Attack

CADC Central Air Data Computer

CAF Combat Air Force

CAPS Critical Action Procedures

CDP Compressor Discharge Pressure

Capt Captain

CAT Critical Action Team

CAUT Caution

CDP Compressor Discharge Pressure

CEMS Comprehensive Engine

Management System

CIP Core Integrated Processor

Col Colonel

CSEL Combat Survivor/Evader Locator

CSFDR Crash Survivable Flight

Data Recorder

CSMU Crash Survivable Memory Unit

CT Currency Training

Cu Copper

DC Direct Current

DFLCC Digital Flight Control Computer

DFLCS Digital Flight Control System

DFR Digital Flight Recorder

DOB Date of Birth

DOC Demonstrative Operational

Capability

DoD Department of Defense

DTC Data Transfer Cartridge

DTS Defense Travel System

EGI Embedded Global Positioning

System/Inertial Navigation System

ELT Emergency Location Transmitter

EDNA Enhanced Diagnostics Air Software

EOD Explosive Ordnance Disposal

EOF End of Flight

EOR End of Runway

EPE Emergency Procedures Evaluation

EPLA Engine Power Lever Angle

EPU Emergency Power Unit

ER Exceptional Release

ETAD ICAO code for Spangdahlem

ETAR ICAO code for Ramstein

ETIC ICAO code for Grafenwoehr

United States Air Force Accident Investigation Board Report

Class A, F-16CM, Spangdahlem Air Base, Germany

F-16CM, T/N 91-0366, 11 August 2015

EUCOM European Command

FBP Fuel Boost Pump

FCIF Flight Crew Information File

FDP Flight Duty Period

FDT Fan Discharge Temperature

FL Flight Lead

FLCS Flight Control System

FO(D) Foreign Object Debris or Damage

FP Flight Profile

FS Fighter Squadron

ft Feet

FTIT Fan Turbine Inlet Temperature

FTU Formal Training Unit

FW Fighter Wing

g/G Gravitational Force

GCU Generator Control Unit

G-Ex G-Awareness Exercise

GPS Global Positioning System

GTA Grafenwoehr Training Area

HFACS Human Factors Analysis and

Classification Systems

Hg Mercury

HPT High Pressure Turbine

HUD Heads-Up Display

IAW In Accordance With

ICAO International Civil Aviation

Organization

IFF Introduction to Fighter

Fundamentals

IFOC In Flight Operations Check

IFR In Flight Rules

IMDS Integrated Maintenance Data System

IMIS Integrated Maintenance

Information System

in. Inches

IP Instructor Pilot

IPI In-Processing Inspection

IQ Instrument Qualification

ISA Integrated Servoactuator

ISB Interim Safety Board

ITADS Intelligent Trending and

Diagnostics System

ITL Individual Task List

ITP Individual Task Plan

IUID Item Unique Identification

JA(G) Judge Advocate

JEIM Jet Engine Intermediate Maintenance

JFS Jet Fuel Starter

JHMCS Joint Helmet Mounted Cueing

System

JMTC Joint Multinational Training

Command

JOAP Joint Oil Analysis Program

JPRC Joint Personnel Recovery Center

JTAC Joint Terminal Attack

Controller

K Thousand

KCAS Knots Calibrated Airspeed

KIAS Knots Indicated Airspeed

KIO Knock-It-Off

KTAS Knots True Airspeed

Kts Knots

L Local Time

LEF Leading Edge Flap

LM-Aero Lockheed Martin Aeronautics

Company

LPT Low Pressure Turbine

LPU Life Preserver Unit

Lt Col Lieutenant Colonel

LWD Left Wing Down

M Mach

MA Mishap Aircraft

Maj Major

MAJCOM Major Command

MDEC Modernized Digital Electronic

Control

MEC Main Engine Control

MEMSC Modernized Engine Monitoring

System Computer

MF Mishap Flight

MFL Maintenance Fault Listing

MFSOV Main Fuel Shutoff Valve

MICT Management Internal

Control Toolset

MIL Military

MILSEC Military Security

MMC Modular Mission Computer

MOA Military Operating Area

MS Mishap Sortie

MSL Mean Sea Level

United States Air Force Accident Investigation Board Report

Class A, F-16CM, Spangdahlem Air Base, Germany

F-16CM, T/N 91-0366, 11 August 2015

MXG Maintenance Group

NATO North Atlantic Treaty

Organization

ND Nose Down

NHBB New Hampshire Ball Bearings

NM Nautical Miles

NOTAMs Notices to Airmen

OG Operations Group

OH Overhaul

OJT On the Job Training

OPR Officer Performance Report

Ops Tempo Operations Tempo

ORM Operational Risk Management

OSC On Scene Commander

OSS Operation Support Squadron

PA Public Affairs

PACS Production Acceptance Certification

Standards

PCS Permanent Change of Station

PDG Programmable Display Generator

PE Personnel Evaluations

PEX Patriot Excalibur

PHA Periodic Health Assessment

PLF Parachute Landing Fall

PMEL Precision Measurement Equipment

Laboratory

PMP Packaged Maintenance Plan

PR Pre Flight

PSI Pounds Per Square Inch

QA Quality Assurance

QIMSS Quality Information Management

Standard System

QVI Quality Verification Inspections

RCO Range Control Officer

RPM Revolutions Per Minute

RTB Return-To-Base

RWD Right Wing Down

SA Situational Awareness

SAR Search and Rescue

SAT Surface Attack Tactics

SAU Signal Acquisition Unit

SDR Seat Data Recorder

SEAD Suppression of Enemy Air

Defenses

SEFE Standardization Evaluation Flight

Examiner

SEPT Simulator Emergency Procedures

Training

SIB Safety Investigation Board

SII Special Interest Item

SME Subject Matter Expert

SOF Supervisor of Flying

SS System Status

TCTO Time Compliance Technical Order

TER Triple Ejector Rack

TDY Temporary Duty Assignment

TGP Targeting Pod

T/N Tail Number

TO (T.O.) Technical Order

TOD Technical Order Data

TOP-3 Operations Supervisor

UAV Unmanned Aerial Vehicle

UHF Ultra High Frequency

UPT Undergraduate Pilot Training

USAFE United States Air Forces in Europe

USAFRICOM United States Africa

Command

USEUCOM United State European

Command

VFR Visual Flight Rules

VHF Very High Frequency

VMC Visual Meteorological Conditions

VOC Volatile Organic Compound

VSV Variable Stator Vane

VVI Vertical Velocity Indication

WCD Work Control Document

Z Zulu

The above list was compiled from the Summary of Facts, Statement of Opinion, Index of Tabs,

and attached tabs.

United States Air Force Accident Investigation Board Report

Class A, F-16CM, Spangdahlem Air Base, Germany

F-16CM, T/N 91-0366, 11 August 2015

PSEUDONYMS

ADCC1 Assistant Dedicated

Crew Chief 1

ADCC2 Assistant Dedicated

Crew Chief 2

ADCC3 Assistant Dedicated

Crew Chief 3

ADCC4 Assistant Dedicated

Crew Chief 4

ADCC5 Assistant Dedicated

Crew Chief 5

AFE MBR Aircrew Flight Equipment

Member

AMDS/CC Aerospace Medicine

Squadron Commander

AMXS/CC Aircraft Maintenance

Squadron Commander

Army General Engineer

Assistant Superintendent

AT1 Avionics Technician 1

AT2 Avionics Technician 2

AT3 Avionics Technician 3

AT4 Avionics Technician 4

Bioenvironmental Engineer

Command and Control

Co-Worker

DCC1 Dedicated Crew Chief 1

DCC2 Dedicated Crew Chief 2

DCC3 Dedicated Crew Chief 3

DCC4 Dedicated Crew Chief 4

DCC5 Dedicated Crew Chief 5

DCC6 Dedicated Crew Chief 6

DW1 Depot Worker 1

DW2 Depot Worker 2

DW3 Depot Worker 3

DW4 Depot Worker 4

DW5 Depot Worker 5

DW6 Depot Worker 6

DW7 Depot Worker 7

DW8 Depot Worker 8

DW9 Depot Worker 9

DW10 Depot Worker 10

DW11 Depot Worker 11

DW12 Depot Worker 12

DW13 Depot Worker 13

DW14 Depot Worker 14

DW15 Depot Worker 15

DW16 Depot Worker 16

DW17 Depot Worker 17

DW-Unknown 1 Depot Worker-Unknown 1

DW-Unknown 2 Depot Worker-Unknown 2

E&E1 Electrical &

Environmental Technician 1

E&E2 Electrical &

Environmental Technician 2

EM1 Engine Mechanic 1

EM2 Engine Mechanic 2

EM3 Engine Mechanic 3

Expediter

FO Fuel Operator

FSRT Fuel Systems Repair

Technician

GE AE General Electric

Aviation Engineer

Intel Briefer

ISB IO1 ISB Investigating Officer 1

ISB IO2 ISB Investigating Officer 2

ISB PM1 ISB Pilot Member 1

ISB PM2 ISB Pilot Member 2

LA Legal Advisor

MC Mishap Commander

MDO Mishap Director of Operations

Mechanic 1

Mechanic 2

MED MBR Medical Member

MFP1 Mishap Flight Pilot 1

MFP3 Mishap Flight Pilot 3

MFP4 Mishap Flight Pilot 4

MOSC1 Mishap On Scene

Commander 1

MOSC2 Mishap On Scene

Commander 2

MP Mishap Pilot

MSOF Mishap Supervisor

of Flying

United States Air Force Accident Investigation Board Report

Class A, F-16CM, Spangdahlem Air Base, Germany

F-16CM, T/N 91-0366, 11 August 2015

vii

MX MBR Maintenance Member

MXG QA Maintenance Group

Quality Assurance

NHBB Manager

Notifier 1

Notifier 2

OGD Operations Group Deputy

PM Pilot Member

Pro Sup Production Superintendent

RC Range Controller

REC Recorder

SIB AFE SIB Aircrew Flight

Equipment Member

SIB AFLCMC/EBHJ Advisor

SIB AFLCMC/LPSEBB Advisor 1

SIB AFLCMC/LPSEBB Advisor 2

SIB AFRL/RXSA Advisor SIB Air Force

Research Laboratory Materials

Integrity Branch Advisor

SIB AFSEC Advisor SIB Air Force

Safety Center Advisor

SIB AFSEC MAAF ADVISOR1 SIB Safety

Center Mishap Analysis &

Animation Facility Advisor 1

SIB AFSEC MAAF ADVISOR2 SIB Safety

Center Mishap Analysis &

Animation Facility Advisor 2

SIB AFSEC REP1 SIB Air Force

Safety Center Representative 1

SIB AFSEC REP2 SIB Air Force

Safety Center Representative 2

SIB BP SIB Board President

SIB GE Advisor SIB General

Electric Advisor

SIB GL SIB German Liaison

SIB HF SIB Human Factors Member

SIB IO SIB Investigating Officer

SIB LM Advisor 1 SIB Lockheed

Martin Advisor 1

SIB LM Advisor 2 SIB Lockheed

Martin Advisor 2

SIB MEDO SIB Medical Officer

SIB MO SIB Maintenance Officer

SIB PM SIB Pilot Member

SIB REC1 SIB Recorder 1

SIB REC2 SIB Recorder 2

SME1 Subject Matter Expert 1

SME2 Subject Matter Expert 2

Superintendent

W&B Weight and Balance

Authority

WG REP Woodward Governor

Representative

Wingman 1

Wingman 2

Wingman 3

Witness 1

Witness 2

Witness 3

Witness 4

Witness 5

Witness 6

Witness 7

Witness 8

Witness 9

Witness 10

Witness Verifier

WS1 Weapons Specialist 1

WS2 Weapons Specialist 2

WS3 Weapons Specialist 3

WS4 Weapons Specialist 4

WS5 Weapons Specialist 5

WS6 Weapons Specialist 6

WS7 Weapons Specialist 7

WS8 Weapons Specialist 8

WS9 Weapons Specialist 9

WS10 Weapons Specialist 10

WS11 Weapons Specialist 11

WS12 Weapons Specialist 12

WS13 Weapons Specialist 13

WS14 Weapons Specialist 14

WS15 Weapons Specialist 15

WS REP Wing Safety Representative

The above list was compiled from the Summary of Facts, Statement of Opinion, Index of Tabs,

and attached tabs.

United States Air Force Accident Investigation Board Report

Class A, F-16CM, Spangdahlem Air Base, Germany

F-16CM, T/N 91-0366, 11 August 2015

SUMMARY OF FACTS

1. AUTHORITY AND PURPOSE

a. Authority

On 4 December 2015, Major General Timothy M. Zadalis, Vice Commander, United States Air

Forces in Europe-Air Forces Africa (USAFE-AFAFRICA), appointed Colonel Jill A. Long to

conduct an aircraft accident investigation of the F-16CM aircraft mishap, tail number 91-0366,

which occurred on 11 August 2015 near Grafenwoehr, Germany (Tab Y-3 to Y-5). The aircraft

accident investigation was conducted in accordance with Air Force Instruction (AFI) 51-503,

Aerospace and Ground Accident Investigations, and was convened at Spangdahlem Air Base

(AB), Germany from 5 January 2016 through 18 February 2016 (Tab Y-3 and Y-8). The following

board members were also appointed: Lieutenant Colonel Medical Member, Captain Pilot Member,

Captain Legal Advisor, Senior Master Sergeant Maintenance Member, Master Sergeant Aircrew

Flight Equipment (AFE) Member, and a Staff Sergeant Recorder (Tab Y-3). The USAFE-

AFAFRICA Staff Judge Advocate appointed an F-16 Engine Propulsion Subject Matter Expert

(SME) and a Main Engine Control SME on 13 January 2016 (Tab Y-6).

b. Purpose

In accordance with AFI 51-503, Aerospace and Ground Accident Investigations, this accident

investigation board conducted a legal investigation to inquire into all the facts and circumstances

surrounding this Air Force aerospace accident, prepare a publicly releasable report, and obtain and

preserve all available evidence for use in litigation, claims, disciplinary action, and adverse

administrative action.

2. ACCIDENT SUMMARY

On 11 August 2015, at approximately 0731 Zulu (Z), the mishap aircraft, a Block 50 F-16CM, tail

number 91-0366, assigned to the 480th Fighter Squadron (480 FS), 52nd Operations Group (52

OG), 52nd Fighter Wing (52 FW), Spangdahlem AB, Germany, crashed on a training mission in

a wooded area near Grafenwoehr, Germany (Tabs J-2, J-8, N-3, S-2 to S-4, and V-5.4). The

mishap flight included: the flight lead - mishap flight pilot 1 (MFP1), mishap pilot (MP), mishap

flight pilot 3 (MFP3), and mishap flight pilot 4 (MFP4) (Tabs K-2 to K-3, V-1.1, V-1.3, V-3.1, V-

3.3, V-4.1, V-5.1, and V-5.4). The pilots, referred to by the pseudonyms of MFP1, MP, MFP3,

and MFP4, are also designated by the following mission callsigns, respectively: ROCKY 01,

ROCKY 02, ROCKY 03, and ROCKY 04. The flight took off as a four-ship at 0659Z to conduct

a Basic Surface Attack mission in the airspace designated as EDR-136 near Grafenwoehr,

Germany (Tabs R-10, V-3.3, and V-5.5). Upon entering the airspace, ROCKY 01 initiated a

standard G-Exercise (G-Ex) maneuver (Tab V-3.3). During the first 90 degree turn of the

maneuver, MP/ROCKY 02 noticed a loss of thrust and engine indications commensurate with an

engine malfunction (Tab V-1.3). MP/ROCKY 02 immediately initiated a “Knock-It-Off” radio

United States Air Force Accident Investigation Board Report

Class A, F-16CM, Spangdahlem Air Base, Germany

F-16CM, T/N 91-0366, 11 August 2015

call at 0729:13Z (Tabs N-2 and V-1.3). ROCKY 01 initiated the required response procedures

ending with MP/ROCKY 02 stating “2’s got a major engine malfunction, I’m losing RPM now”

(Tabs N-2 and V-1.3). MP/ROCKY 02 immediately sought a divert airfield while accomplishing

the critical action procedures for the emergency (Tab V-1.4). The other mishap flight members

assisted MP/ROCKY 02 by providing general direction to the nearest airfield and maintaining

situational awareness for the flight (Tab V-4.3 and V-5.9). After realizing the mishap aircraft’s

engine would not restart, MP/ROCKY 02 turned the mishap aircraft in a direction to avoid damage

to personnel and property on the ground (Tab V-1.4 and V-4.4). MP/ROCKY 02 ejected,

sustaining only minor injuries (Tabs V-1.14 and X-4). The mishap aircraft was destroyed upon

impact; the loss was valued at $39,796,422.00 (Tab P-4). Damage to non-US government property

consisted of damage to trees, shrubbery, soil, and crops (Tabs S-4 to S-6, S-9 to S-10, V-38.4 to

V-38.7, V-39.5 to V-39.7, and V-40.4 to V-40.6).

3. BACKGROUND

a. United States Air Forces in Europe-United States Air Forces Africa (USAFE-

AFAFRICA)

With headquarters at Ramstein AB, Germany, USAFE-AFAFRICA is a

major command of the United States Air Force and is the air component for

two Department of Defense unified combatant commands: the US European

Command (USEUCOM), which is responsible for US military relations with

the North Atlantic Treaty Organization (NATO) and 51 countries on two

continents; and the US Africa Command (USAFRICOM), which is

responsible for building defense capabilities, responding to crises, and

deterring and defeating transnational threats in order to advance US interests

and promote security, stability, and prosperity in Africa (Tab CC-3 to CC-4 and CC-7). USAFE-

AFAFRICA executes the Air Force, USEUCOM, and USAFRICOM missions with forward-based

infrastructure and airpower to conduct and enable both global and theater operations. Combined

USEUCOM and USAFRICOM cover more than 15 million square miles, encompass 104

independent states, and possess more than one-fifth of the world’s population (Tab CC-3).

b. Third Air Force (3 AF)

Third AF is USAFE-AFAFRICA’s component numbered air force, which

provides airpower to USEUCOM and USAFRICOM. Based at Ramstein AB,

Germany, 3 AF directs all USAFE-AFAFRICA forces engaged in

contingency and wartime operations in the USEUCOM and USAFRICOM

areas of responsibility. Along with its headquarters operations directorate,

3 AF is comprised of 10 wings, two groups, and an Air Operations Center

(Tab CC-8).

United States Air Force Accident Investigation Board Report

Class A, F-16CM, Spangdahlem Air Base, Germany

F-16CM, T/N 91-0366, 11 August 2015

c. 52nd Fighter Wing (52 FW)

The 52 FW maintains, deploys, and employs F-16 aircraft and TPS-75 radar

systems in support of NATO and national defense directives. The wing

supports the Supreme Allied Commander Europe with mission-ready

personnel and systems providing expeditionary air power for suppression of

enemy air defenses, close air support, air interdiction, counter-air, air strike

control, strategic attack, combat search and rescue, and theater airspace

control. The wing also supports contingencies and operations other than war

when required (Tab CC-10).

d. 52nd Operations Group (52 OG)

The 52 OG consists of the 480th Fighter Squadron (480 FS), the 606th Air

Control Squadron, and the 480th Operations Support Squadron (480 OSS).

The 480 FS operates both C and D model F-16 (C/D) Fighting Falcon aircraft

(Tab CC-12).

e. 480th Fighter Squadron (480 FS)

The 480 FS operates the Block 50, F-16CM Fighting Falcon, which is

informally referred to as the Viper. As USAFE's only F-16 Block 50 squadron,

the 480 FS provides the Supreme Headquarters Allied Forces Europe and

USAFE commanders with dedicated suppression of enemy air defense, air

interdiction, counter-air, and close air support capability (Tab CC-14).

f. F-16 Fighting Falcon

The F-16 Fighting Falcon is a highly maneuverable, multi-role fighter

aircraft. It has proven itself in the air-to-air combat and air-to-surface attack

roles and provides a “relatively low-cost, high-performance weapon

system” for the US and allied nations (Tab CC-15 to CC-17).

4. SEQUENCE OF EVENTS

a. Mission

ROCKY flight, a flight of four F-16s assigned to the 480 FS, was scheduled to fly a Basic Surface

Attack mission on 11 August 2015 to the Grafenwoehr Training Area (GTA) range, EDR-136 (Tabs

K-2 and V-5.5). Each F-16 aircraft in ROCKY flight was configured for the air-to-surface mission

with six lightweight practice bombs, BDU-33s, loaded on Triple Ejector Racks (TERs) (Tab K-4 and

K-7). While on the range the mission is observed by a range control officer (Tab V-8.1). The range

control officer on-duty the day of the mishap is referred to by the pseudonym “Range Controller”

(Tab V-8.1).

United States Air Force Accident Investigation Board Report

Class A, F-16CM, Spangdahlem Air Base, Germany

F-16CM, T/N 91-0366, 11 August 2015

b. Planning

On the morning of 11 August 2015, ROCKY flight attended a mass brief at 0500Z with GURU 01

flight, a flight of two F-16s scheduled for the same range complex twenty minutes after ROCKY

flight (Tabs R-20, R-29, and V-6.1). The mass brief included information pertaining to weather,

aircraft status, airspace, range issues, Notices to Airmen (NOTAMS), and divert airfield

information (Tab V-6.1 and V-17.1). The weather forecast indicated visual flight rules (VFR)

conditions at both Spangdahlem AB and GTA range (Tab F-12). The on-duty Operations

Supervisor, or TOP-3, conducted the mass brief and did not note anything unusual the day of the

mishap (Tab V-17.1 to V-17.2).

At approximately 0520Z, the mass brief concluded and ROCKY 01 began briefing the roles and

responsibilities for their four-ship mission (Tab R-20). ROCKY 01 briefed all the required items

to safely conduct the mission (Tab R-20). At 0540Z, ROCKY flight finished their brief and donned

their flight equipment (Tab R-20). ROCKY flight submitted an Operational Risk Management

(ORM) sheet identifying potential risks associated with flying operations (Tabs V- 17.1, V-18.3,

and AA-5). The Operations Supervisor reviewed the ORM sheet and did not note anything which

required higher authority approval or that precluded safe flying operations (Tabs V-17.1 and AA-

5).

c. Preflight

MP/ROCKY 02 did not notice anything abnormal during his preflight inspection of the mishap

aircraft and engine start was uneventful (Tab V-1.3 and V-1.10). During ground operations the

pilot originally designated in the number two position of the formation, MFP4, found a

maintenance issue with his assigned aircraft and moved to a spare becoming ROCKY 04 (Tab V-

1.3, V-5.4, and V-5.5). MP/ROCKY 02, who was originally designated ROCKY 04, was

renumbered and assigned the ROCKY 02 position (Tabs R-6, V-1.3, V-5.4, and V-5.5). Three F-

16s in ROCKY flight taxied to the End of Runway (EOR) for final checks: ROCKY 01, ROCKY

02, and ROCKY 03 (Tabs R-6, V-1.3, and V- 5.5). ROCKY 04 joined the formation at the EOR,

enabling ROCKY flight to depart as a four-ship of F-16s (Tabs R-6, V-1.3, and V- 5.5).

d. Summary of Accident

ROCKY flight took off from Spangdahlem AB at 0659Z on 11 August 2015 (Tab R-10). The

airfield status was designated by the on-duty mishap supervisor of flying, as VFR with Ramstein

as the divert airfield (Tab V-31.1). The observed weather included calm winds with unrestricted

visibility (Tab F-12). Takeoff, departure, and navigation to the airspace were uneventful (Tab V-

1.3 and V-4.3). The GTA range is approximately 200 miles from Spangdahlem AB (Tab V-1.3).

In order to enter the range airspace and get below a few scattered clouds, ROCKY flight descended

from cruise altitude to approximately 5,000 feet mean sea level (MSL) (Tabs F-12 and R-6).

Upon entering the range airspace, ROCKY flight members switched from München Center

frequency to the Range Controller’s frequency, and began check-in procedures (Tab V-1.10). The

Range Controller reported environmental conditions for the GTA range as: light and variable

United States Air Force Accident Investigation Board Report

Class A, F-16CM, Spangdahlem Air Base, Germany

F-16CM, T/N 91-0366, 11 August 2015

winds, unrestricted visibility, altimeter 29.99 [inches mercury, in. Hg], and no hazards associated

with the airspace (Tab V-8.1).

ROCKY 01 directed his flight members to change their avionics from navigation mode to

employment mode and to increase airspeed to 400 knots for the G-Ex (Tabs N-2, R-3, and V-5.5).

The G-Ex is a required maneuver anytime five G’s or more are anticipated during the mission, to

test equipment under G-loading and prepare the pilot for higher G-loading later in the mission

(Tabs V-5.5 and BB-9). The G-Ex consists of one 90 degree turn using four to five Gs, then a

subsequent 90 degree turn up to the maximum allowable G-loading per the aircraft configuration

(Tabs V-5.5 and BB-9).

ROCKY flight was flying in an offset container formation in order to conduct the G-Ex;

MP/ROCKY 02 was in a line abreast position on the left side of ROCKY 01 (Tab V-4.6). At

0729:00Z ROCKY 01 called over the radio “For G warm up, 90 Left,” which commanded ROCKY

flight to begin the maneuver (Tab N-2). MP/ROCKY 02 advanced the throttle to Military (MIL)

power, rolled his wings to an 80 degree bank angle, and then immediately noticed a loss of thrust

as he was slung forward in the seat (Tab V-1.3 and V-1.8). MP/ROCKY 02 looked at the engine

instruments and confirmed that the engine was operating below normal limits and was not

responding to throttle position (Tab V-1.3). MP/ROCKY 02 initiated a “Knock-It-Off” call at

0729:13Z (Tab N-2). The Knock-It-Off procedure was executed by all flight members (Tab V-

1.3 to V-1.4 and V-4.3 to V-4.4). ROCKY 01 acknowledged responsibility for deconfliction with

the radio call “Rocky 2, Press” at 0729:26Z (Tabs N-2, V-3.3, and V-3.8). MP/ROCKY 02 radioed

to flight members that his aircraft was experiencing “a major engine malfunction” and was losing

Revolutions Per Minute (RPM) at 0729:30Z (Tab N-2).

ROCKY flight members promptly provided MP/ROCKY 02 with the heading to the nearest

emergency divert airfield and notified the Range Controller of the emergency, specifically an

engine malfunction with intentions of departing the airspace to the northwest (Tabs N-2, V-1.4,

V-4.3, and V-5.9). ROCKY 01 collapsed to an emergency chase formation on the mishap aircraft

in order to relay any visual anomalies (Tab V-3.3 and V-4.3). At that time, ROCKY 01 did not

see anything abnormal with the mishap aircraft (Tab V-3.6 to V-3.7).

MP/ROCKY 02 immediately accomplished the critical action procedures for low thrust at low

altitude; initiating two airstart attempts, with no signs of engine recovery (Tabs J-7, V-1.3, and V-

1.4). MP/ROCKY 02 jettisoned fuel tanks at 0729:50Z (Tab J-7). ROCKY 03 notified the Range

Controller of the jettisoned fuel tanks and directed ROCKY 04 to obtain coordinates for the

jettisoned fuel tanks impact point (Tabs R-21, V-4.4, and V-5.9). MP/ROCKY 02 actuated the Jet

Fuel Starter (JFS) at 0730:01Z and reported a “significant increase in thrust” at 0730:23Z (Tabs J-

7 and V-1.4). MP/ROCKY 02 thought the mishap aircraft engine had recovered to normal

operation (Tab V-1.4). Another loss of thrust occurred a few seconds later, which was confirmed

by data displayed on the engine instruments (Tabs J-7 and V-1.3 to V-1.4). ROCKY flight

members assisted MP/ROCKY 02 by confirming he had accomplished the restart procedures (Tab

V-1.4). MP/ROCKY 02 initiated two more airstart attempts experiencing one more occurrence of

a potential engine restart followed immediately by another engine malfunction (Tab J-7). At

0731:21Z MP/ROCKY 02 attempted a fifth, and final, unsuccessful airstart procedure (Tab J-7).

United States Air Force Accident Investigation Board Report

Class A, F-16CM, Spangdahlem Air Base, Germany

F-16CM, T/N 91-0366, 11 August 2015

MP/ROCKY 02 determined an ejection was necessary but recognized that the mishap aircraft’s

flight path would place populated areas at risk (Tab V-1.4 and V-4.4). MP/ROCKY 02

maneuvered his aircraft to ensure the impact would avoid all populated areas (Tab V-1.4). Once

the aircraft’s flight path was satisfactory, MP/ROCKY 02 began to climb and slow for ejection

(Tab V-1.4 and V-1.15). Once the ejection posture was obtained, the ejection sequence was

initiated at 0731:40Z with an airspeed of 156 knots and approximately 400 feet above ground level

(AGL) (Tabs J-7 and V-1.4). ROCKY 03 witnessed the ejection and notified the Range Controller

that MP/ROCKY 02 had a good parachute and there was a downed aircraft (Tabs N-3 and V-4.4).

ROCKY flight passed coordinates to the Range Controller, N 49-48.12 E011-38.30, to initiate

Search and Recovery procedures (Tabs R-18, R-35, V-8.1, and V-8.3). The remaining ROCKY

flight members requested that the Range Controller notify emergency crews while they orbited

over the crash site and established communication with MP/ROCKY 02 on the ground, confirming

he had no serious injuries (Tab V-4.4).

e. Impact

The mishap aircraft crash site was approximately 190 nautical miles east of Spangdahlem AB in a

wooded area (Tab H-21). According the Range Controller, the crash site was located at

coordinates N 49-48.12 E011-38.30 Elevation 1392 feet (Tab R-35). The mishap aircraft initially

impacted trees at an attitude of 8 degrees nose low, approximately wings level, with a descending

22 degree flight path, and heading approximately 266 degrees true (Tab H-21). The debris

stretched approximately 400 feet long and 200 feet wide along the mishap aircraft flight path (Tab

J-3). The wings had separated from the mishap aircraft but were intact (Tab H-21). The aft

fuselage, vertical tail, right horizontal tail, and engine were intact (Tab H-21). The mishap aircraft

forward of the engine was broken into small pieces (Tab J-2). The canopy was located

approximately 1,200 feet east of the crash site and the parachute was located approximately 1,590

feet east of the crash site (Tabs H-21 and J-3).

f. Egress and Aircrew Flight Equipment (AFE)

The ejection parameters were 156 knots calibrated airspeed (KCAS) and 2,200 barometric altitude

(approximately 400 feet AGL) (Tab J-2). Based on these parameters, MP/ROCKY 02’s Advanced

Concept Ejection Seat II (ACES II) functioned properly using Mode 1 operation with no anomalies

noted (Tab H-2 to H-8). MP/ROCKY 02 followed ejection procedures in accordance with training

instructions (Tabs V-1.13 and BB-19 to BB-39). Upon checking for successful parachute

operation, MP/ROCKY 02 identified and successfully corrected crossed risers (Tab V-1.13).

Subsequently, MP/ROCKY 02 was able to verify a fully inflated canopy, the seat kit had deployed,

and the life raft had inflated (Tab V-1.13). MP/ROCKY 02 lifted his visor, removed his mask,

and prepared for a parachute landing fall position (Tab V-1.13). A German citizen assisted

MP/ROCKY 02 with successfully securing all aircrew flight equipment (Tab V-1.14 to V-1.15).

The equipment worn by MP/ROCKY 02 was recovered from the crash site (Tab H-19). All

inspections were current and performed by qualified AFE technicians (Tab H-19). Minor

documentation errors were noted on the drogue parachute and the ACES II Survival Kit which did

not affect proper operations or deployment (Tab H-19 to H-20).

A post-crash analysis was performed on all equipment (Tab H-19). The Joint Helmet Mounted

United States Air Force Accident Investigation Board Report

Class A, F-16CM, Spangdahlem Air Base, Germany

F-16CM, T/N 91-0366, 11 August 2015

Cueing System (JHMCS) helmet was cracked on the left side (Tab H-19). The ACES II Survival

Kit internal components were unused and found to be serviceable (Tab H-19). The attached life

raft was found deflated but showed the bottle had operated properly (Tabs H-19 and V-1.13). The

Air Ace Survival Vest was fitted with the Combat Survival/Evader Locater (CSEL) radio, which

MP/ROCKY 02 confirmed operated properly by transmitting on frequency 282.8 (Tabs H-19 and

V-1.13).

g. Search and Rescue (SAR)

The crash occurred at approximately 0731Z (Tabs J-8 and N-3). Approximately two to three

minutes after ejection, MP/ROCKY 02 was able to establish communications with ROCKY 03 on

the guard frequency using his CSEL radio (Tab V-1.13 to V-1.14). MP/ROCKY 02 informed

ROCKY 03 that no serious injuries were sustained during the ejection (Tab V-1.13 to V-1.14).

The crash site coordinates were relayed by the mishap flight to the Range Controller, who then

informed the 52 FW Commander that he would coordinate with fire, police, environmental, and

both the US Army and German Bundeswehr [military] (Tab R-35). First responders arrived on

scene within minutes of initial notification (Tab V-1.14 and V-4.4). MP/ROCKY 02 was

transported by German ground ambulance to Bayreuth Hospital (Tab R-35).

h. Recovery of Remains

Not applicable.

5. MAINTENANCE

a. Forms Documentation

A thorough review was conducted of the mishap aircraft’s active Air Force Technical Order

(AFTO) 781 series forms; no discrepancies were noted (Tab D-3 to D-17). There were seven open

Time Compliance Technical Orders (TCTOs) in the active forms, none of which restricted the

mishap aircraft from flying operations (Tab D-15 to D-17). Additionally, there was no overdue

hourly or calendar scheduled maintenance (Tab D-13 to D-14). Integrated Maintenance Data

System (IMDS) historical records for the 90 days prior to the mishap were also reviewed and

revealed no previous maintenance discrepancies that could be correlated to the mishap (Tab U-

16). The work package cover sheets, checklists, daily maintenance summaries, and IMDS

documentation during the time the engine was in the Jet Engine Intermediate Maintenance (JEIM)

shop showed all appropriate maintenance had been accomplished (Tab U-4 to U-5 and U-16).

b. Inspections

The total airframe operating time prior to the mishap was 6,469.2 hours (Tab D-11). The mishap

engine was a F110-GE-129 engine, serial number GE0E538149, and was installed into the mishap

aircraft on 5 September 2014 (Tab J-38 to J-39). The mishap engine had 3,456.6 hours total engine

operating time and 271.6 flight hours remaining before its next scheduled 400 hour engine phase

inspection (Tab D-11 and D-13). Phase inspections are regularly scheduled maintenance

United States Air Force Accident Investigation Board Report

Class A, F-16CM, Spangdahlem Air Base, Germany

F-16CM, T/N 91-0366, 11 August 2015

inspections performed at a 400 flight-hour interval on this mission design series aircraft (Tab BB-

43).

Prior to being placed in the mishap aircraft on 5 September 2014, the mishap engine had 11 TCTOs

completed, one time change component was replaced, and four additional scheduled inspections

accomplished (Tab U-4 to U-5). After overhaul, a thorough test of the engine was conducted and

revealed no abnormalities (Tab U-6).

On 20 April 2015, the following maintenance actions were accomplished: an 800-hour engine

exhaust nozzle inspection, a 100-hour engine borescope inspection, a 25-hour joint oil analysis

program (JOAP) sample test, and two engine TCTOs, with no abnormalities noted in the

documentation (Tab U-14 to U-16).

On 10 August 2015, maintenance personnel performed a combined preflight/basic postflight

inspection on the mishap aircraft (Tab D-3). This type of inspection is valid for 72 hours and was

valid at the time of the mishap mission (Tab BB-41). The on-duty Production Superintendent

signed the Exceptional Release to release the aircraft from maintenance to the pilot (Tabs D-3 and

V-16.1). This release certifies that the active maintenance forms were reviewed and the aircraft

was safe for flight (Tab BB-18).

The last maintenance technicians to inspect the aircraft prior to takeoff were the end of runway

(EOR) crew (Tab BB-42). The EOR crew is responsible for removing the safety pins from any

munitions loaded on the aircraft and checking for any obvious discrepancies, such as open doors

and panels or incorrect hydraulic systems pressure; the EOR crewmembers stated they did not note

anything abnormal about the mishap aircraft (Tab V-13.1 and V-15.1).

c. Maintenance Procedures

Summaries of the Main Engine Control’s (MEC) work control documents, dating 29 August 2013

to 17 December 2013, and the MEC Test to Overhaul to Test Notes, dating 27 June 2013 to

10 December 2013, were reviewed (Tab J-80 to J-84). During that time, an overhaul of the

component was accomplished along with TCTOs 6J3-4-120-504 and 6J3-4-120-505 by personnel

assigned to the 552nd Commodities Maintenance Squadron, 76th Commodities Maintenance

Group, 76th Maintenance Wing at the Oklahoma City Air Logistics Complex at Tinker AFB,

Oklahoma (Tab J-80 to J-96). During the overhaul process, there were five instances where the

MEC failed test/calibration procedures and was returned for further maintenance (Tab J-80 to J-

84). It was noted by maintenance and test personnel at the facility at Tinker AFB that test failures

are not uncommon; however, multiple failures for the same fault are rare (Tabs V-24.2, V-26.1,

V-33.2, and GG-11). Additionally, when the necessary maintenance corrections have been

completed, the MEC will go through all test/calibration procedures and only be placed in service

once it has successfully passed re-testing (Tab V-26.1 to V-26.2).

According to the AFLCMC/LPSEBB MEC Overhaul and Test Shop Visit Report, the MEC failed

test/calibration on 27 June 2013 for compressor discharge pressure (CDP), on 24 July 2013 for

CDP, on 15 August 2013 for CDP, on 10 September 2013 for tachometer calibration, and on

United States Air Force Accident Investigation Board Report

Class A, F-16CM, Spangdahlem Air Base, Germany

F-16CM, T/N 91-0366, 11 August 2015

19 October 2013 for CDP (Tab J-84). Each time corrective actions were taken and subsequent

testing/calibration was conducted, with the final testing and validation taking place on

17 December 2013 (Tab J-80 to J-84). After passing the final testing, the MEC was re-stamped

with a new part number per TCTO 6J3-4-120-505, marked as serviceable, and returned to service

(Tabs J-93 to J-96 and U-3).

The mishap engine was inducted into the JEIM facility on 29 January 2014 (Tab U-4). On 11 July

2014, the overhauled MEC was installed on the mishap engine (Tab J-76).

Starting on 30 July 2014, the mishap engine went through post-maintenance engine run and

operational checks; all appropriate inspections and checks were completed with no anomalies

noted (Tab U-6 and U-16). Following operational testing the engine was preserved for storage

and sent to the spare engine line on 1 August 2014 (Tab U-16). On 8 August 2014, a non-serially

tracked line was replaced and the engine was sent to the test cell section to accomplish a follow up

leak check (Tab U-16). All necessary leak checks were accomplished and no defects were noted.

The engine was preserved and returned to the spare engine line on 8 August 2014 (Tab U-16).

On 5 September 2014, the engine was installed on the mishap aircraft (Tab J-39). The engine was

later removed in order to facilitate other maintenance [not associated with the engine] on

29 January 2015 and again on 30 April 2015; after each subsequent reinstallation no engine defects

were noted (Tab U-16).

d. Maintenance Personnel and Supervision

Interviews conducted with maintenance personnel indicated all preflight activities were normal

and no anomalies with personnel or aircraft were noted (Tab V-9.1, V-11.1, V-12.1, V-13.1, V-

14.1, V-15.1, and V-16.1). Training records were reviewed for all maintenance personnel who

serviced and maintained the mishap aircraft, as well as the JEIM members who installed the mishap

MEC, and all were fully qualified (Tab T-3 to T-23 and T-130 to T-190).

Training records for the MEC depot maintenance facility workers and test members at Tinker AFB,

Oklahoma who overhauled the mishap MEC were reviewed and all personnel were qualified (Tabs

G-56 to G-59 and T-191 to T-208). Training procedures at the maintenance facility were reported

as conducted “on-the-job” (Tab V-27.1 and V-33.1). The maintenance facility’s quality assurance

program at Tinker AFB includes documented bi-annual personnel evaluations and random quality

assurance verification inspections (Tab V-26.2 and V-30.1). Some personnel from the

maintenance facility interviewed reported appropriate resources and training were available to

perform their assigned duties (Tab V-24.1, V-27.1, V-28.1, V-32.1, V-33.1, and V-34.1).

However, one worker interviewed reported several problems with available resources, including

old test stands that would frequently break and consistently leak, old and bent tools, and inaccurate

gauges used to calibrate the tachometer and speed (Tab V-26.1).

e. Fuel, Hydraulic, and Oil Inspection Analyses

Fuel samples were taken and tested post-mishap from all equipment used to refuel the mishap

aircraft including the fuel truck, the upper hydrant system fill stand, and the aircraft (Tab U-7 to

United States Air Force Accident Investigation Board Report

Class A, F-16CM, Spangdahlem Air Base, Germany

F-16CM, T/N 91-0366, 11 August 2015

U-13). All samples were within technical data limits and free from contamination (Tab U-7 to U-

13).

The post-impact fire prevented analysis of aircraft oil samples; however, all oil servicing

equipment was sampled and within technical limits (Tab U-14). A review was conducted of the

mishap aircraft’s records to include: the AFTO 781, the Non Destructive Inspection Records, and

the associated records on teardown and inspection of the engine; there was no evidence of

excessive contaminants, oil consumption, or other negative trends associated with the mishap

engine (Tabs J-38 to J-71 and U-14).

f. Unscheduled Maintenance

A review of all maintenance actions performed on the mishap engine that were not the result of a

scheduled inspection revealed two instances of such unscheduled maintenance accomplished on

the mishap engine (Tab J-41). The first took place on 22 October 2014, when the augmentor fuel

control (AFC) was replaced due to an aircraft maintenance fault listing (MFL) 082 “Sig AFC” and

MFL 018 “Aug Inhib” (Tab J-41, J-73, and J-75). The second instance took place on 8 December

2014, when the engine T4B pyrometer was replaced due to a MFL 013 “Trend Fault” (Tab J-41

and J-73). Neither maintenance action was associated with the main engine control.

6. AIRFRAME, MISSILE, OR SPACE VEHICLE SYSTEMS

a. Structures and Systems

According to post-flight analysis, the mishap aircraft was destroyed upon impacting the ground

(Tab J-2). The aircraft crashed into a heavily wooded area on a slight uphill slope, resulting in a

small debris field approximately 400 feet by 200 feet at its widest points (Tab J-2 to J-3). The

aircraft forward of the engine was severely broken apart, with pieces ranging in size from a few

inches to a few feet (Tab J-2). The aft portion of the fuselage, vertical tail (with the rudder still

attached), right horizontal tail, and engine were in one piece, although the lower portion was

severely damaged by the impact and post-impact fire (Tab J-2 and J-19). Both aircraft wings

separated from the aircraft (Tab J-2). “The left wing of the aircraft hit several trees during the

descent” (Tab J-2). The left wing was found with the left leading edge flaps still attached;

however, the left flaperon was detached from the left wing (Tab J-2 and J-19). The right wing was

found with the right leading edge flaps and right flaperon still attached (Tab J-2 and J-19). The

left horizontal tail separated from the rest of the aircraft’s empennage but was found lying next to

the aircraft (Tab J-19). The Digital Flight Control System Accumulator was found intact in the

tail section and was not removed (Tab J-24). The MP’s main parachute was located approximately

1,590 feet from the site of aircraft impact (Tabs H-21 and J-3). The canopy was found generally

intact with two longitudinal cracks in the transparency and several smaller cracks in the canopy

frame, approximately 1,200 feet from the aircraft (Tab J-3).

The recovered wreckage was returned to Spangdahlem Air Base (Tab J-48 and Q-2). The Crash

Survivable Flight Data Recorder (CSFDR) and the Digital Flight Control Computer (DFLCC),

United States Air Force Accident Investigation Board Report

Class A, F-16CM, Spangdahlem Air Base, Germany

F-16CM, T/N 91-0366, 11 August 2015

commonly referred to as the Seat Data Recorder (SDR), were recovered and sent for analysis (Tab

J-6, J-12, and J-13).

The Digital Flight Recorder (DFR), Modular Mission Computer (MMC), and Programmable

Display Generator (PDG) were recovered but the extent of the damage prevented recovery of data

from these systems. Therefore, the stored information on these devices was not available for

analysis (Tab J-19).

The Signal Acquisition Unit (SAU), Data Transfer Cartridge (DTC), Generator Control Unit

(GCU), and Emergency Power Unit (EPU) were not recovered (Tab J-12, J-19, and J-25).

The Main Engine Control (MEC), Modernized Digital Engine Control (MDEC), and Modernized

Engine Monitoring System Computer (MEMSC) were recovered and sent to the original

equipment manufacturers for analysis (Tab J-68). The Jet Fuel Starter (JFS) was recovered and

examined by Lockheed Martin (Tab J-21). Two fuel samples were taken from the aircraft

wreckage and sent to the Air Force Petroleum Agency for analysis (Tab U-7 to U-10).

b. Evaluation and Analysis

(1) Recorded Data

Based on analysis of the data retrieved from the CSFDR and the SDR, the mishap aircraft was

operating normally from takeoff to a flight time of approximately 29 minutes (Tab J-17). Various

fault indications and stale source data from the Embedded Global Positioning System/Inertial

Navigation System (EGI), indicated a loss of 115-volt Alternating Current (AC) Bus No. 1 power

to the Central Air Data Computer (CADC), 28-volt Direct Current (DC) Emergency DC Bus No.

1 power to the EGI and Emergency DC Bus No. 2 power to the Store Enhancement Relay 2756K2

(Tab J-17). As stated in Lockheed Martin Aeronautical Company Report of F-16C 91-0366

Mishap Investigation, Summary of SDR Data:

Indications of a loss of electrical power without Integrated Servoactuator (ISA) faults

indicated the engine was operating in a sub-idle range. Electrical power was restored to the

CADC and EGI within approximately 2.5 seconds, which is the typical delay for starting the

emergency power unit and for the emergency generator to come on line. Pilot ejection

occurred between the last recording of the mishap flight (MF) at 0:31:30 and the next

scheduled recording at 0:31:45. The flight control system was functioning through the time

of pilot-initiated ejection (Tab J-17).

A recording anomaly in the CSFDR data was observed in the throttle signal. The recorded values

were consistently low by between 15-18 degrees (Tab J-11 to J-12). This anomaly was consistent

with previous occasions where this was noted and it was determined that the throttle potentiometer

had been mis-rigged (Tab J-11). This signal; however, “only goes to the CSFDR and it does not

affect engine performance” (Tab J-11).

United States Air Force Accident Investigation Board Report

Class A, F-16CM, Spangdahlem Air Base, Germany

F-16CM, T/N 91-0366, 11 August 2015

(2) Flight Control Surfaces

According to Lockheed Martin Aeronautics Company, “all flight control surfaces were found at

the crash site” (Tab J-19). An examination of the flight control surfaces included: the leading

edge flaps; speedbrakes; and the ISAs for the right and left flaperons, the right and left horizontal

tail, and the rudder (Tab J-19 to J-20). Lockheed Martin concluded that all flight controls were

functioning properly at the time of the mishap and the speedbrakes were closed at the time of

ground impact (Tab J-19 to J-20 and J-25 to J-26).

(3) Landing Gear

The CSFDR and DFLCC indicated that the landing gear handle was in the up position (Tab J-25).

“The landing gear actuators were in the up position and landing gear door actuators were in the

closed position, indicating the landing gear was in the up position” (Tab J-25).

(4) Fuel System

The CSFDR recorded a fuel quantity of 8,192 pounds at 0729:12.63Z, shortly after the engine roll

back (Tab J-22). “Fuel flow just prior to engine roll back was 10,688 pounds per hour” (Tab J-

22). After roll back, “fuel flow was in the idle to sub-idle range with the exception of the two

engine restarts” (Tab J-22). The Master Fuel Switch was “on” and the Main Fuel Shutoff Valve

(MFSOV) was in the “fully open” position (Tab J-22 to J-23). Analysis determined fuel flow

system to the main engine control was normal until the time of impact (Tabs J-25 and GG-5).

(5) Hydraulic System

The System A hydraulic reservoir was filled to approximately 44% of volume and the System B

hydraulic reservoir was filled to approximately 61% of volume, which is considered to be a normal

fill level (Tab J-24). Both the CSFDR and the SDR data indicated that both hydraulic systems

were operating properly (Tab J-24 and J-26).

(6) Electrical Systems

The CSFDR and DFLCC data showed that the electrical system was operating properly at the time

of impact (Tab J-24).

(7) Emergency Power System (EPU)

The EPU was not recovered; however, the CSFDR data was intact and indicated that the EPU was

operating normally (Tab J-25).

(8) Propulsion Interface

The engine was returned to Spangdahlem Air Base and disassembled for inspection (Tabs J-48

and Q-2). It was determined that both system A and B hydraulic pumps maintained approximately

1700 psi (Tab J-20). The CSFDR recorded an “Engine Flameout” MFL at 0729:11.62Z and

approximately 38 seconds later, the “HYD A/Eng Oil LOW discrete” was set due to low oil

United States Air Force Accident Investigation Board Report

Class A, F-16CM, Spangdahlem Air Base, Germany

F-16CM, T/N 91-0366, 11 August 2015

pressure (Tab J-20). The JFS compressor and JFS brake accumulators were examined. The

examination determined that there was no evidence of pre-impact damage (Tab J-21 to J-22 and

J-25).

(9) Engine

The following items were inspected by the Air Force Life Cycle Management Center/F-110

Engineering Section (AFLCMC/LPSEBB) and were found to have no pre-impact damage: fan,

compressor, combustor, high pressure turbine (HPT), low pressure turbine (LPT),

augmentor/exhaust nozzle, main engine bearings, accessory gear box, fuel tubes and manifolds,

air tubes and manifolds, oil tubes and manifolds, as well as various engine accessories specifically

listed in Tab J-70 (Tab J-49 to J-71).

The following engine accessories were either not found or were unidentifiable: the fuel boost

pump (FBP), the fuel/oil cooler, and the oil level/temperature sensor (Tab J-70). The electrical

cables associated with the engine were severely damaged; therefore, no determination as to pre-

impact condition could be assessed (Tab J-70).

(a) Modernized Digital Engine Control (MDEC)

According to AFLCMC/LPSEBB, The MDEC was “distorted and fused with slag from other

engine accessories and airframe components due to the post-impact fire” (Tab J-68). The MDEC

housing burned through in multiple places, exposing the internal circuit cards (Tab J-68). The

MDEC was sent to the original equipment manufacturer, Honeywell International, Inc., in order

to attempt recovery of the data; however, due to extensive fire damage no data was recovered (Tab

J-68).

(b) Modernized Engine Monitoring System Computer (MEMSC)

According AFLCMC/LPSEBB, the MEMSC was “distorted, burned through and the circuit cards

were damaged due to impact and the post-impact fire” (Tab J-69). The MEMSC was sent to the

original equipment manufacturer, Hamilton Sundstrand, to attempt recovery of the data; however,

due to extensive fire damage no data was recovered (Tab J-69).

Due to post-impact fire, the MEC was distorted and fused with slag from other engine accessories

and airframe components (Tab J-67 to J-68). The MEC was also burned through, exposing internal

MEC components (Tab J-68). The MEC was sent to the original equipment manufacturer,

Woodward Governor, Inc., for teardown and analysis (Tab J-68).

General Electric Aviation and Woodward Governor, Inc. conducted analysis and teardown of the

MEC, using standard disassembly techniques whenever possible (Tab J-132). Due to the degree

of post-impact fire damage, the majority of the teardown involved non-standard techniques

including cutoff wheels and pry bars (Tab J-132). The hydroclone filter assembly was found to be

heavily damaged by the impact and post-impact fire (Tab J-132 to J-133). The hydroclone filter

United States Air Force Accident Investigation Board Report

Class A, F-16CM, Spangdahlem Air Base, Germany

F-16CM, T/N 91-0366, 11 August 2015

assembly and overspeed trip set screw showed either no-abnormalities/damage or the

abnormalities/damage were determined to be unrelated to component failure (Tab J-68 and J-133).

The overspeed trip set screw was “still engaged” and CFSDR data shows the overspeed trip

mechanism was functioning per design before impact (Tabs J-43 to J-47, J-68, and GG-9).

The MEC is a sophisticated hydro-mechanical computer (Tab GG-6). The MEC is bolted to the

engine gearbox and is rotated by an input shaft from the gearbox (Tab GG-6). The MEC senses

core speed in the tachometer system, using the rotating input shaft connected to the gearbox. When

the sensed speed from this input shaft exceeds 113%, the overspeed mechanism will activate,

shutting off fuel flow to the engine combustor (Tab GG-6). The overspeed trip mechanism is

designed to initiate at 113% RPM and reset when the core speed drops below 55% RPM (Tab GG-

5 and GG-9). However, according to the CSFDR data the MEC was sending the 113% RPM signal

to the overspeed trip mechanism when the actual RPM reached 102% causing the engine to roll

back to approximately 35% RPM (Tabs J-43 to J-46 and GG-9). These erroneous signals were

caused by contamination found on the flyweight within the tachometer assembly of the tachometer

ballhead (Tab GG-9). These flyweights rotate from the input shaft, providing centrifugal force,

which moves the pilot valves – ultimately leading to a three-dimensional fuel cam, which the main

engine control computer uses to set fuel flow and to trigger the overspeed trip (Tab GG-6). The

flyweights in the tachometer system operate within a precisely calculated system based on

centrifugal force; any material changes in the mass of the flyweights will upset this system (Tab

GG-9). The additional mass on the flyweight caused the MEC to sense an RPM higher than actual,

which triggered early activation of the overspeed trip mechanism (Tab GG-9).

Activation of the overspeed trip mechanism ceases all fuel flow to the engine combustor (Tab GG-

12). The energy released from the combustion of the fuel with air produces high energy

combustion gases, which can then be accelerated in the exhaust nozzle to produce engine thrust

(Tab GG-12). This complete cessation of fuel flow made airstart attempts impossible, as the

engine requires fuel to start and operate (Tab GG-12). Once the core speed dropped below 55%,

the overspeed mechanism would reset, allowing fuel flow to the engine once again (Tab GG-12).

However, selecting an EPLA setting above idle would cause the engine to accelerate to the point

where the overspeed trip would once again prematurely activate, shutting off the fuel to the engine

again (Tab GG-12). This sequence of events would make airstarts ultimately unsuccessful, as the

engine would repeatedly shut off unless left at an idle setting (Tab GG-12). The engine, at idle,

only produces minimal thrust by design, and keeping the engine at idle would not produce enough

thrust to sustain flight (Tab GG-12).

The governor ballhead assembly was removed and inspected (Tab J-133). The governor ballhead

assembly contains a matched set of duplex bearings which allow the governor ballhead to rotate,

and are referred to as an "upper," or inboard, and "lower," or outboard, bearing (Tab GG-8). The

outboard-side (lower) governor ballhead bearing cage was found to be fractured and liberated from

the bearing (Tab J-133 to J-134). Personnel at the Woodward Metallurgical Lab visually inspected

a one-inch sector of the lower governor ballhead bearing cage and did not find any evidence of

fatigue (Tab J-134). The fracture surface was so heavily smeared that the exact nature of the

fracture could not be determined (Tab GG-8).

During inspection of the governor ballhead

bearings, the ‘V’ markings were found to indicate the bearings were installed in the correct

United States Air Force Accident Investigation Board Report

Class A, F-16CM, Spangdahlem Air Base, Germany

F-16CM, T/N 91-0366, 11 August 2015

orientation (Tab J-135). The governor ballhead bearing cages are a two-piece design (Tab GG-8).

The governor ballhead inboard (upper) side of the lower governor bearing cage was found to be

loose between the two bearings, resulting in wear marks on the cage (Tab J-135 to J-136). The

tachometer assembly was removed and inspected, along with the flyweight location, and contact

damage to the snap ring and laminate shims of the unit were found (Tab J-137). The tachometer

ballhead was sent to Woodward Metallurgical Lab for further evaluation, where a light metal spray

of copper (Cu) and silver (Ag) was found on the inside diameter of the flyweight (Tab J-137). The

tachometer ballhead bearing and flyweights were disassembled for further evaluation (Tab J-138).

During this evaluation, a witness mark and a metal particle were found on the underside of the

tachometer ballhead flyweight (Tab J-138 to J-139). This metal particle was consistent with the

governor ballhead bearing cage material or shim lamination material (Tabs J-139). The tachometer

ballhead bearing was inspected under further magnification and a small piece of material was

found loose in the bearing (Tab J-139). This small piece of material was removed for analysis by

the Woodward Metallurgical Lab and was found to match the recovered piece of the bearing cage

from the failed lower governor ballhead bearing (Tab J-139).

The MEC uses internal fuel pressures to perform internal functions (Tab GG-9). These internal

fuel pressures are used through the MEC (Tab GG-9). This requires internal passages within the

MEC to port these fuel pressures to the various areas of the MEC that utilize the internal fuel

pressures for proper MEC function, in addition to a lubrication function (Tab GG-9). The governor

system and tachometer system interact directly with each other via these MEC internal fuel

pressures (Tab GG-9).

According to the Air Force Research Laboratory’s F-16 Main Engine Control (MEC) Bearing

Failure (Failure Analysis) Report, they concluded that “failure of the lower [governor ballhead]

bearing retainer (cage) [within the lower ballhead bearing cage] occurred before ground impact”

(Tabs J-105 and GG-8) and that migration of the retainer cage fragment through a gear to a

different location would not occur during an impact event (Tab J-105).

AFLCMC/LPSEBB’s Engine Investigation Report concluded the engine RPM was at sub-idle at

the time of impact; the engine was not responding to commanded throttle setting at time of impact;

no pre-impact turbomachinery distress was observed during engine teardown; and the abnormal

engine response observed is consistent with failure of the MEC overspeed trip system (Tab J-71).

(10) Escape System

The CSFDR recorded the beginning of the pilot-initiated ejection sequence at 0731:40.13Z (Tab

J-25). See section 4.f. above for details.

7. WEATHER

a. Forecast Weather

Forecast weather conditions for takeoff and landing at Spangdahlem AB on 11 August 2015 met

visual meteorological conditions (VMC) (Tab F-12). Based on this forecast the, mishap supervisor

United States Air Force Accident Investigation Board Report

Class A, F-16CM, Spangdahlem Air Base, Germany

F-16CM, T/N 91-0366, 11 August 2015

of flying declared the status at Spangdahlem AB as VFR with Ramstein AB designated as the

alternate (Tabs R-27 and V-31.1). Winds at Spangdahlem AB were expected to be calm, less than

10 knots, out of the northwest with no significant weather and unrestricted visibility (Tab F-12).

The forecast weather from 1,000 feet up to 40,000 feet in the EDR-136 airspace was expected to

have a few clouds from 7,000 feet to 9,000 feet with light winds out of the west trending to the

southeast (Tab F-6 and F-12). All applicable divert bases were forecasted to be VMC (Tab F-8).

No turbulence, icing, thunderstorms, or any other hazards were forecasted (Tab F-12).

b. Observed Weather

Checking into the airspace on 11 August 2015, MP observed unrestricted visibility with “scattered

to light clouds” above his flight level (Tab V-1.5). Surface winds were light and variable in EDR-

136 with clear visibility and an altimeter setting of 29.99 in. Hg (Tab V-8.1). Before and after the

mishap, observed conditions were calm to light winds out of the northwest with unrestricted

visibility, clear skies, and no significant weather (Tab F-12). Additionally, no rapid changes in

pressure or any other hazards were observed (Tab F-12).

c. Space Environment

Not applicable.

d. Operations

The mishap flight conducted the mission within the prescribed operational weather limitations in

accordance with paragraph 5.3.1 of AFI 11-214, Air Operations Rules and Procedures (Tab BB-

10).

8. CREW QUALIFICATIONS

All members of ROCKY flight were current and qualified four-ship flight leads (Tabs G-2 and V-

17.1). MP, MFP3, and MFP4 were experienced per requirements found in paragraph 6.2, AFI 11-

2F-16, Volume 1, Flying Operations, F-16-Pilot Training (Tabs G-2 and BB-4). Additionally,

MFP3 and MFP4 were current and qualified instructor pilots, with MFP3 being a graduate of the

Weapons Instructor Course (Tabs G-2, V-4.2 to V-4.3, and V-5.2). MFP4 was Chief of Standards

and Evaluations and a current and qualified flight examiner (Tabs G-2 and V-5.2 to V-5.3). The

Operations Supervisor considered the overall experience level of members in ROCKY flight to be

“high” (Tab V-17.1 to V-17.2).

MP had a total of 675.0 flight hours, was an experienced four-ship flight lead, and was qualified

as a Supervisor of Flying (Tab G-2 and G-5). On the day of the mishap, MP had completed all

required training, pilot read files, monthly critical action procedures, and was up-to-date in all

currencies for the type of mission assigned (Tab G-48 to G-54). MP completed an instrument

qualification evaluation on 26 November 2014, a no-notice mission evaluation on 12 June 2014,

and was certified as a qualified combat-mission pilot with no discrepancies noted during either

evaluation (Tab G-23 to G-26).

United States Air Force Accident Investigation Board Report

Class A, F-16CM, Spangdahlem Air Base, Germany

F-16CM, T/N 91-0366, 11 August 2015

In the 90 days preceding the mishap, MP’s flying history in the F-16 was summarized as:

(Tab G-6)

9. MEDICAL

a. Qualifications

Based on a review of the MP’s medical record, MP was medically qualified for flying duty at the

time of the mishap as annotated on AF Form 1042 Medical Recommendation for Flying or Special

Operational Duty dated 2 March 2015 (Tab X-3 and X-5). The most recent Periodic Health

Assessment (PHA) was accomplished 2 March 2015, at which time he was medically cleared (Tab

X-3). MP’s last dental exam was accomplished on 29 June 2015, with a Dental Classification of

1; indicating no unresolved dental health problems (Tab X-3). MP possesses one waiver for

medical conditions inconsistent with flying duty (Tab X-3). This waiver was initiated as a Flying

Class One waiver and granted by Air Education and Training Command (AETC) on 14 July 2009

(Tab X-3). Upon graduation from Undergraduate Pilot Training (UPT), the waiver was changed

to a Flying Class Two waiver and was renewed on 29 March 2012 by AETC and again on

16 March 2015 by USAFE with a current expiration date of 31 March 2018 (Tab X-3).

b. Health

A medical record review and an interview of MP indicate he was in excellent health prior to the

mishap (Tabs V-2.1 and X-4). According to the PHA on 2 March 2015, he exercised regularly

and ate a healthy diet (Tabs V-2.1 and X-4). As previously stated in section 9.a. above,

MP was

determined to be medically qualified for flight duty at the time of the accident

(Tab X-3). A review

of the post-accident medical examination record revealed only minor post-accident injuries –

cervicalgia (pain in the neck); no pre-accident injuries were noted (Tab X-4). MP was treated at a local

national facility, observed overnight, and released the following day

(Tab X-4). The 480 FS flight

surgeon returned MP to flight status on 18 August 2015

(Tab X-4).

c. Pathology

All mishap flight members and maintainers associated with the mishap aircraft provided samples

for toxicology testing. All samples were negative (Tab X-3 to X-4).

F-16

Hours

Sorties

Last 30 Days

14.6

Last 60 Days

28.3

Last 90 Days

48.5

United States Air Force Accident Investigation Board Report

Class A, F-16CM, Spangdahlem Air Base, Germany

F-16CM, T/N 91-0366, 11 August 2015

d. Lifestyle

During MP’s interview, no evidence was presented to suggest MP’s habits, behaviors, stress-level,

or lifestyle were factors the day of the mishap (Tabs V-2.1 and X-4).

e. Crew Rest and Crew Duty Time

During MP’s interview, MP stated he obtained 8 to 9 hours of sleep and 13 to 14 hours of crew

rest prior to reporting for duty on the day of the accident (Tab V-2.1). The amount of sleep the

MP obtained and his subsequent crew rest met the requirements of paragraph 2.1, AFI 11-202,

Volume 3, General Flight Rules (Tab BB-7).

10. OPERATIONS AND SUPERVISION

a. Operations

The 480 FS Director of Operations considered the operations tempo of the unit to be moderately-

high to high at the time of the mishap (Tab V-17.1). MP had been assigned temporary duty, away

from home station, a total of 119 days of the preceding 365 days (Tab G-55). MP’s most recent

temporary duty was 30 days in duration, ending on 5 August 2015, to a large force exercise where

MP performed flight duties (Tabs G-55 and V-2.1). At the time of the mishap, the 480 FS had 45

pilots (27 assigned and 18 attached), of which 34 were experienced and 19 of the experienced

pilots were also instructor pilots (Tab G-2).

b. Supervision

The 480 FS Operations Supervisor validated all aircrew were qualified to execute assigned flight

duties in accordance with paragraph 4.4.5 of AFI 11-418, Flying Operations–Operations

Supervision (Tabs G-48 and BB-45). Furthermore, a review of Certification of Aircrew

Qualifications, aircrew currencies, Go/No-Go Summary, and training records confirmed all

members of the mishap flight were trained and qualified to accomplish the assigned mission (Tab

G-48 to G-54).

11. HUMAN FACTORS ANALYSIS

Human Factors were evaluated using the Department of Defense Human Factors Analysis and

Classification System: acts, preconditions, supervision, and organizational influences (Tab BB-

14 to BB-16). The AIB Medical Member reviewed the following evidence: toxicology reports

and medical and dental records for all mishap flight members, including MP, and maintainers

associated with the mishap aircraft; 17 72-hour and 14-day histories; and the Aeromedical

Information and Medical Waiver Tracking System of MP. Additionally, the AIB Medical Member

was present for MP’s 72-hour and 14-day history interview before the AIB. Based on the evidence

reviewed, the AIB Medical Member did not note any anomalies or evidence of adverse human

factors (Tab X-3 to X-5).

United States Air Force Accident Investigation Board Report

Class A, F-16CM, Spangdahlem Air Base, Germany

F-16CM, T/N 91-0366, 11 August 2015

12. GOVERNING DIRECTIVES AND PUBLICATIONS

a. Publically Available Directives and Publications Relevant to the Mishap

AFI 11-2F-16, Volume 1, Flying Operations, F-16-Pilot Training, 20 April 2015

AFI 11-202, Volume 3, General Flight Rules, 7 November 2014

AFI 11-214, Air Operations Rules and Procedures, 14 August 2012

AFI 11-418, Flying Operations–Operations Supervision, 14 October 2015

AFI 51-503, Aerospace and Ground Accident Investigations, 14 April 2015

AFI 91-204, Safety Investigations and Reports, 12 February 2014, Corrective Actions Applied on

10 April 2014

NOTICE: All directives and publications listed above are available digitally on the Air Force

Departmental Publishing Office website at: http://www.e-publishing.af.mil.

b. Other Directives and Publications Relevant to the Mishap

DoD HFACS, Version 7.0, 12 February 2014

T.O 00-20-1, Aerospace Equipment Maintenance Inspection, Documentation, Policies, and

Procedures, 15 October 2015

T.O. 1F-16CJ-6-11, Scheduled Inspection and Maintenance Requirements USAF Series F-16C

and F-16D Using F110-GE-129/129B Engine Block 50, 1 November 2013, with Change 5, dated

1 November 2015 (partially redacted)

USAFE Code of Conduct Continuation Training Instructor Guide, Operations Support,

Emergency Parachute Training, 1 March 2011

c. Known or Suspected Deviations from Directives or Publications

None.

4 August 2016 JILL A. LONG, Colonel, USAF

President, Accident Investigation Board

United States Air Force Accident Investigation Board Report

Class A, F-16CM, Spangdahlem Air Base, Germany

F-16CM, T/N 91-0366, 11 August 2015

STATEMENT OF OPINION

F-16CM, T/N 91-0366

NEAR GRAFENWOEHR, GERMANY

11 AUGUST 2015

Under 10 U.S.C. § 2254(d) the opinion of the accident investigator as to the cause of, or the factors

contributing to, the accident set forth in the accident investigation report, if any, may not be considered as

evidence in any civil or criminal proceeding arising from the accident, nor may such information be

considered an admission of liability of the United States or by any person referred to in those conclusions

or statements.

1. OPINION SUMMARY

On 11 August 2015, an F-16CM tail number 91-0366, assigned to the 52nd Fighter Wing,

Spangdahlem Air Base, Germany experienced an unrecoverable engine malfunction while on a

local training mission near Grafenwoehr, Germany. The mishap resulted in pilot ejection and a

total loss of the aircraft. After approximately 29 minutes of flight, the mishap pilot experienced a

loss of thrust. Five attempts were made by the mishap pilot to restart the failed engine. Prior to

ejection the mishap pilot maneuvered the aircraft away from populated areas; ejecting at 156 knots

calibrated air speed and approximately 400 feet above ground level. The mishap pilot sustained

minor injuries. Search and Recovery efforts were facilitated by local German nationals, the

German Bundeswehr, and the US Army. The mishap aircraft was destroyed upon impact; the loss

was valued at $39,796,422.00. Damage to non-US government property consisted of damage to

trees, shrubbery, soil, and crops.

After analyzing technical reports, engineering evaluations, parametric data, physical evidence, Air

Force Instructions, Air Force Technical Orders, maintenance reports, maintenance records, aircrew

training and qualifications, statements about operations and supervision, medical reports, human

factors, visual media, witness testimony, and weather reports – I find by a preponderance of

evidence that the cause of the mishap was a structural failure of the bearing cage within the lower

governor ballhead bearing. This structural failure caused the main engine control to malfunction,

which prohibited fuel flow to the engine. The lack of fuel flow prevented engine restart and

resulted in a complete loss of thrust, requiring the mishap pilot to eject from the mishap aircraft.

2. CAUSE

Data extracted from the Crash Survivable Flight Data Recorder (CSFDR) indicated that the mishap

aircraft’s engine was operating in a sub-idle condition at the time of ground impact. [Note: A sub-

idle condition indicates the engine components are free to rotate but the engine is not producing

sustainable thrust.] This sub-idle condition was caused by early activation of the overspeed trip

mechanism in the main engine control unit.

United States Air Force Accident Investigation Board Report

Class A, F-16CM, Spangdahlem Air Base, Germany

F-16CM, T/N 91-0366, 11 August 2015

Early activation was recorded by the CSFDR, which showed engine core speed “roll back” (the

term roll back is used here as a steady deceleration or reduction in RPM) consistent with overspeed

trip mechanism activation. The overspeed trip mechanism is designed to initiate at 113% RPM

and reset when the core speed drops below 55% RPM. However, according to the CSFDR data

the MEC was sending the 113% RPM signal to the overspeed trip mechanism when the actual

RPM reached 102% causing the engine to roll back to approximately 35% RPM.

In accordance with the design, the main engine control senses core speed via the tachometer system

which receives data via the rotating input shaft connected to the engine gearbox. Flyweights rotate

from the input shaft, providing centrifugal force which moves the pilot valves – ultimately leading

to a three-dimensional fuel cam which the main engine control computer uses to set fuel flow and

to trigger the overspeed trip.

The flyweights in the tachometer system operate within a precisely calculated system based on

centrifugal force; any material changes in the mass of the flyweights will upset this system. During

metallurgical lab analysis a witness mark and a metal particle were discovered on the tachometer

ballhead flyweight denoting contact with a foreign object. The lab also identified a particle of

foreign material loose in the tachometer ballhead bearing. The witness mark, along with material

particles, affected the flyweights’ mass causing the Main Engine Control to record a higher RPM

than actual; thus, commanding early activation of the overspeed trip mechanism.

Technical and engineering analysis shows that one of the duplex bearings in the main engine

control governor system failed. Specifically, the governor cage located in the lower governor

bearing fractured. In the analysis, it is postulated that pieces of the cage were liberated and

migrated into the tachometer system. The tachometer system and the governor system interact

with one another via the fuel within the main engine control system which flows from one system

to the other freely for lubrication purposes as well as its primary function of providing metered

fuel to the engine.

The material found in the tachometer system was analyzed by personnel at Woodward

Metallurgical Lab and found to be consistent with the alloys characteristic of the lower governor

ballhead bearing’s fractured bearing cage. While a direct correlation could not be assigned due to

the destructive nature of the bearing cage fracture, I infer that the witness mark on the tachometer

ballhead flyweight and the material found on the flyweight and ballhead bearing in the tachometer

system were a result of liberated particles in the lower governor ballhead bearing.

It is my opinion that the reason for failure of the bearing cage within the lower governor ballhead

bearing cannot be determined due to the destructive nature of the cage fracture. There simply is

not enough material evidence remaining to permit further analysis

3. CONCLUSION

I find, by a preponderance of evidence, that the cause of the mishap was a structural failure of the

bearing cage in the lower governor ballhead bearing within the main engine control. This structural

failure caused the main engine control to malfunction, which prohibited fuel flow to the engine.

United States Air Force Accident Investigation Board Report

Class A, F-16CM, Spangdahlem Air Base, Germany

F-16CM, T/N 91-0366, 11 August 2015

The lack of fuel flow prevented engine restart and resulted in a complete loss of thrust, requiring

the mishap pilot to eject from the mishap aircraft.

4 August 2016 JILL A. LONG, Colonel, USAF

President, Accident Investigation Board

United States Air Force Accident Investigation Board Report

Class A, F-16CM, Spangdahlem Air Base, Germany

F-16CM, T/N 91-0366, 11 August 2015

INDEX OF TABS

Safety Investigator Information ..................................................................................................... A

Not Used ......................................................................................................................................... B

Not Used ........................................................................................................................................ C

Maintenance Report, Records, and Data ........................................................................................ D

Not Used ......................................................................................................................................... E

Weather and Environmental Records and Data .............................................................................. F

Personnel Records .......................................................................................................................... G

Egress, Aircrew Flight Equipment, Impact, and Crashworthiness Analysis ................................. H

Deficiency Reports........................................................................................................................... I

Releasable Technical Reports and Engineering Evaluations ........................................................... J

Mission Records and Data ............................................................................................................. K

Factual Parametric, Audio, and Video Data From On-Board Recorders ....................................... L

Data From Ground Radar and Other Sources ................................................................................ M

Transcripts of Voice Communications .......................................................................................... N

Any Additional Substantiating Data and Reports .......................................................................... O

Damage Summaries ........................................................................................................................ P

AIB Transfer Documents ............................................................................................................... Q

Releasable Witness Testimony ....................................................................................................... R

Releasable Photographs, Videos, Diagrams, and Animations ........................................................ S

Personnel Records Not Included in Tab G ..................................................................................... T

Maintenance Report, Records, and Data Not Included in Tab D .................................................. U

United States Air Force Accident Investigation Board Report

Class A, F-16CM, Spangdahlem Air Base, Germany

F-16CM, T/N 91-0366, 11 August 2015

Witness Testimony and Statements ............................................................................................... V

Weather and Environmental Records and Data Not Included in Tab F ........................................ W

Statements of Injury or Death ........................................................................................................ X

Legal Board Appointment Documents .......................................................................................... Y

Photographs, Videos, Diagrams, and Animations Not Included in Tab S ...................................... Z

Flight Documents ......................................................................................................................... AA

Applicable Regulations, Directives, and Other Government Documents ................................... BB

Background Information and Fact Sheets .................................................................................... CC

Non-Privileged Safety Investigation Board Witness Statements and Transcripts Not Included in

Tab R ............................................................................................................................................ DD

Non-Privileged Safety Investigation Board 72 Hour – 14 Day Histories Not Included in

Tab R ........................................................................................................................................... EE

Tab L Attachments (DVD) ........................................................................................................... FF

Main Engine Control Subject Matter Expert 1 Data Analysis ..................................................... GG

Tab S Attachment – Animation (DVD) ....................................................................................... HH