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B-2 crash-landing caused by single hydraulic component failure
An Air Force Global Strike Command Accident Investigation Board completed its investigation of a B-2A Spirit mishap that occurred at Whiteman Air Force Base on Dec. 10, 2022.
According to a USAF news release, the B-2A sortie was uneventful until when CryoFit hydraulic coupling failed (i.e., the aircraft experienced a hydraulic system failure related to the Main Landing Gear (MLG)) during its final approach to land. The aircrew declared an in-flight emergency and followed procedures for an emergency landing gear extension. Upon landing, the Left Main Landing Gear (LMLG) collapsed immediately, causing the left wing to strike the runway and drag for several thousand feet as the aircrew worked to bring the aircraft to a stop.
The B-2A came to a stop 9,062 ft down the runway, with the left wingtip on fire in the infield. The fire, fed from the left surge fuel tank, caused the left surge fuel tank to explode, then spread to the left outboard fuel tank, which exploded shortly afterwards.
There were no injuries because of the mishap. Damage to the left wing and LMLG is estimated to be over $300 million. The incident also caused approximately $27,500 in damage to the airfield.
Colonel Jesse W. Lamarand, the AIB President determined, by a preponderance of evidence, that the mishap was caused by a failure of a truck position sequence valve hydraulic coupling. The coupling, which requires liquid nitrogen for installation, expelled from its fitting and created an opening that rapidly drained hydraulic fluid from both systems.
B-2 crash-landing
The crew declared an in-flight emergency and execute emergency procedures because the failure prevented the right main landing gear from extending normally. In fact the left main landing gear had lost structural integrity due to the emergency extension process while all three landing gear appeared to indicate “down and locked” on cockpit displays.
“The hydraulic fluid loss in the primary system, followed by an emergency gear extension, resulted in the hydraulic main landing gear lock actuator having insufficient hydraulic pressure to assist in holding the left main landing gear lock link assembly in place,” the report states.
In addition to the primary cause, the AIB identified two substantially contributing factors:
- Main Landing Gear Design Vulnerabilities: The MLG design vulnerabilities allowed the lock link assembly to move out of the required over-center (locked) position during the emergency gear extension.
- Delayed Fire Suppression: A delay in the application of Aqueous Film Forming Foam to extinguish the fire allowed the flames to spread, causing more damage to the aircraft (Believing USAF policy limited use of aqueous film forming foam to last resort situations, the incident commander initially restricted its use. The most effective fire suppressant was delayed for approximately three minutes and 28 seconds due to this misunderstanding, and flames spread before the left surge fuel tank exploded at approximately 1500 CST, followed by the left outboard fuel tank explosion 10 minutes later).
A recurring issue
As noted by Alert 5, the CryoFit coupling failure is a recurring issue across the B-2 fleet. The investigation found 25 recorded coupling failures fleet-wide, with 10 occurring in main landing gear hydraulic circuits. Five failures specifically involved truck position sequence valve couplings, with two resulting in left main landing gear collapses.
In September 2021 a similar incident led to the discovery that main landing gear lock springs did not meet specifications. A technical order requiring replacement of lock springs and validation of proximity sensor rigging across the fleet was issued by the Air Force in March 2022. The mishap aircraft had completed this modification in June 2022 and recorded 33 landings before the December mishap.
Following the incident, AFGSC temporarily suspended B-2A flights to inspect the fleet. Even during this pause, AFGSC maintained the ability to deploy B-2As for nuclear deterrence and long-range strike missions if needed. Full flight operations resumed on May 22, 2023.
The investigation could not determine the underlying cause of the coupling failure.
The crew was qualified and current for the mission: the instructor pilot had more than 350 hours in the B-2A, while the co-pilot undergoing aircraft commander upgrade training had over 180 hours in the platform. Weather conditions were within prescribed limitations with overcast clouds at 1,000 feet and light winds.
The Spirit
The B-2 Spirit is a multi-role bomber capable of delivering both conventional and nuclear munitions. A dramatic leap forward in technology, the bomber represents a major milestone in the US bomber modernization program.
The first B-2 was publicly displayed on Nov. 22, 1988, when it was rolled out of its hangar at Air Force Plant 42, Palmdale, California. Its first flight was July 17, 1989. The B-2 Combined Test Force, Air Force Flight Test Center, Edwards Air Force Base, California, is responsible for flight testing the engineering, manufacturing and development aircraft on the B-2.
Whiteman AFB, Missouri, is the only operational base for the B-2. The first aircraft, Spirit of Missouri, was delivered Dec. 17, 1993. Depot maintenance responsibility for the B-2 is performed by Air Force contractor support and is managed at the Oklahoma City Air Logistics Center at Tinker AFB, Okla.
The combat effectiveness of the B-2 was proved in Operation Allied Force, where it was responsible for destroying 33 percent of all Serbian targets in the first eight weeks, by flying nonstop to Kosovo from its home base in Missouri and back. In support of Operation Enduring Freedom, the B-2 flew one of its longest missions to date from Whiteman to Afghanistan and back. The B-2 completed its first-ever combat deployment in support of Operation Iraqi Freedom, flying 22 sorties from a forward operating location as well as 27 sorties from Whiteman AFB and releasing more than 1.5 million pounds of munitions. The aircraft received full operational capability status in December 2003. On Jun. 22, 2025 B-2 bombers struck Iranian nuclear sites with GBU-57B Massive Ordnance Penetrators during Operation Midnight Hammer.
Photo credit: U.S. Air Force
