Accident Rockwell B-1B Lancer 85-0089,
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ASN Wikibase Occurrence # 277572
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Date:Wednesday 20 April 2022
Time:22:16 LT
Type:Silhouette image of generic B1 model; specific model in this crash may look slightly different    
Rockwell B-1B Lancer
Owner/operator:US Air Force (USAF)
Registration: 85-0089
MSN: 49
Fatalities:Fatalities: 0 / Occupants:
Aircraft damage: Substantial
Location:Abilene-Dyess AFB, TX -   United States of America
Phase: Standing
Departure airport:-
Destination airport:-
Investigating agency: USAF AIB
Confidence Rating: Accident investigation report completed and information captured
The USAF Rockwell B-1B, 85-0089, assigned to Dyess Air Force Base, 7th Bomb Wing, 7th Maintenance Group 7th Aircraft Maintenance Squadron, experienced a catastrophic engine failure and fire on the no.1 engine while undergoing maintenance on the main ramp at Dyess AFB, Texas. The aircraft suffered catastrophic damage to the no.1 engine, as well as extensive fire damage to the left nacelle and wing. Debris from the explosion struck one airman who suffered minor injuries. The estimated cost of damage sustained by the aircraft was $14,943,680.00.
Shortly before the accident, the Maintenance Crew performed routine corrective maintenance, in accordance with technical orders, in response to the aircraft's malfunctioning no.1 engine variable area exhaust nozzle. During run-up to maximum augmenter to verify correct performance of the no.1 engine variable area exhaust nozzle, the no.1 engine catastrophically failed, ejecting its 2nd Stage Fan Disk from the intake section and severing fuel lines, which caused a fire to erupt in the engine. The 2nd Stage Fan Disk continued to flyaway from the aircraft and landed over five hundred feet from the aircraft. The maintenance crew executed emergency engine shutdown procedures and egressed away from the aircraft. Emergency crews quickly responded and extinguished the fire within ten minutes.

The Accident Investigation Board President found by a preponderance of the evidence that high cycle fatigue on the no.1 engine's 2nd Stage Fan Disk was the cause of the accident. Laboratory testing demonstrated that high cycle fatigue initiated a crack on the surface of the 2nd Stage Fan Disk at the corner of a blade slot and the forward face of the disk. The crack, once initiated by the stress induced from repeated acceleration and deceleration of the engine, was propagated by a mix of high cycle and low cycle fatigue. The crack and its initial growth increased the stress beyond the 2nd Stage Fan Disk's yield strength, leaving it susceptible to low cycle fatigue. The surface crack grew to a depth of approximately 0.7 inches before the 2nd Stage Fan Disk broke apalt causing the #1 engine to fail catastrophically. The root cause of the high cycle fatigue that caused the initial crack in the 2nd Stage Fan Disk could not be determined.


Accident investigation:
Investigating agency: USAF AIB
Report number: 
Status: Investigation completed
Duration: 8 months
Download report: Final report


Revision history:

21-Apr-2022 21:38 Iceman 29 Added
07-Jan-2023 18:39 harro Updated [Time, Registration, Cn, Total occupants, Departure airport, Destination airport, Source, Embed code, Damage, Narrative, Accident report]

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