What happened
On 18 June 2021, a Boeing 787-8, registration G-ZBJB, was parked at London Heathrow Airport Stand 583 undergoing preparations for a cargo flight to Frankfurt. A ground maintenance team was working to resolve several fault messages related to the nose landing gear (NLG) door solenoids. According to the approved maintenance procedures, the crew could defer the repairs provided the landing gear was cycled to verify the doors functioned correctly. To ensure safety during this test, downlock pins were intended to be installed to prevent the gear from retracting.
During the procedure, the lead engineer selected the landing gear lever to the 'up' position. Unexpectedly, the nose landing gear retracted, causing the nose of the aircraft to strike the ground. The impact caused significant damage to the underside of the forward fuselage, the NLG doors, and the forward lower engine cowlings. The sudden movement also caused a cargo loading team member to be struck by a cargo door, resulting in one minor injury to the loader and one minor injury to the co-pilot.
The investigation
The AAIB investigation established that the nose landing gear downlock pin had been incorrectly placed. Instead of being inserted into the designated downlock pin hole, the pin had been inserted into the downlock link assembly apex pin bore. The investigation found that the physical design of the nose landing gear assembly made this error possible, as the two available holes were positioned so closely together that they were difficult to distinguish visually. Furthermore, the insertion of the pin provided tactile and auditory feedback—a 'click'—that could mislead a technician into believing the pin was correctly seated.
Investigators also found that while a Service Bulletin and an Airworthiness Directive (AD) existed to rectify this specific design vulnerability, the modification had not yet been completed on G-ZBJB. The decision to defer the implementation of this safety update was influenced by the economic impacts of the COVID-19 pandemic and internal organizational processes.