Synopsis
On 18 June 2021, at approximately 0651 UTC, a Boeing 787-8, registration G-ZBJB, was being prepared for a cargo flight from London Heathrow Airport to Frankfurt. During a Dispatch Deviation Guide (DDG) procedure to clear maintenance messages related to an existing Acceptable Deferred Defect (ADD), the nose landing gear (NLG) retracted. This caused damage to the lower forward fuselage, NLG doors, and engine cowlings. Door 2 left (Door 2L) struck the top of mobile steps and separated from the fuselage. One person on the cargo loader received minor injuries.
Sequence of Events
At approximately 0620 hrs, the crew arrived and found three ground engineers on the flight deck working to clear status messages associated with an ADD for an NLG door-closed solenoid valve. The crew discussed the rectification work, estimated at 40 minutes, and revised the off-block time to 0725 hrs. The commander, the Overseas Engineer (OSE), and two ground engineers left the flight deck, leaving the co-pilot in the right seat and the lead ground engineer in the left seat.
The lead ground engineer worked through the NLG status messages on a ground maintenance laptop. The DDG required hydraulic pressure and cycling the cockpit landing gear lever from down to up then back to down. The lead engineer instructed two mechanics to fit landing gear locking pins and to attach a ground communications headset. The mechanics located five pins and proceeded to the NLG. Mech 1 pointed to the location, and Mech 2 fitted the NLG locking pin. They then fitted pins to the right and left main landing gear (MLG). Mech 1 returned to the flight deck to confirm pin installation. After further confirmation via headset, the lead engineer applied hydraulic power. Before selecting the landing gear lever, he requested final confirmation. Mech 1 checked that warning flags were visible and that the pallet loader was clear of personnel. After confirmation, the lead engineer pressed lock override and selected the landing gear lever to up. The NLG retracted, causing the aircraft nose to strike the ground.
Injuries and Aircraft Damage
One ground loading team member on the pallet loader under the forward cargo door was slightly injured as the door moved down with the fuselage. The co-pilot sustained a minor injury. Three personnel in the forward cabin and galley fell but were uninjured. The aircraft's nose came to rest on the articulated arm of a ground power unit, crushing the cable arm. Damage included the lower forward fuselage, NLG doors, and both engine cowlings. Door 2L was severely damaged by contact with stairs, with hinge and actuating mechanism failure; the door remained attached only by its wiring loom.
During recovery, examination found the NLG downlock pin fitted in the NLG apex pin bore, adjacent to the correct downlock pin hole. With the pin in this position, pressing lock override and selecting the landing gear lever to up with hydraulic power caused NLG retraction.
Previous Occurrence and Preventative Measures
In 2018, another Boeing 787 experienced NLG retraction due to the downlock pin being installed in the apex pin inner bore. As a result, the manufacturer published Service Bulletin (SB) B787-81205-SB320040-00 on 12 March 2019, providing instructions to install an insert in the apex pin bore to prevent incorrect installation. Issue 02 was published on 23 October 2020. This SB was mandated by FAA Airworthiness Directive (AD) 2019-23-07 on 16 January 2020, with a 36-month compliance time. This AD had not yet been implemented on G-ZBJB.
The operator had issued a Technical News leaflet on 9 April 2020 and again on 9 December 2020 showing correct and incorrect NLG downlock pin positions. Following this accident, the operator re-issued the leaflet on 19 June 2021 and planned to expedite incorporation of the AD.
Further Investigation
The investigation continues and will consider safety procedures associated with landing gear maintenance and factors that may have contributed to the incorrect installation. A final report will be published in due course.