A locking pin designed to prevent a Boeing 787’s nose landing gear from retracting remained inside its storage box when a Lufthansa Dreamliner collapsed at Frankfurt Airport (FRA), German investigators have found.
The discovery offers the clearest explanation yet for the June 4, 2026, incident involving Lufthansa Boeing 787-9 D-ABPQ, although Germany’s Federal Bureau of Aircraft Accident Investigation, or BFU, has not issued a final determination of cause.
Technicians were troubleshooting a fault involving the aircraft’s main landing-gear door control system while the 787 was parked at a terminal stand and being prepared for a flight to Los Angeles.
The maintenance procedure required the landing-gear lever to be moved to the up position. Locking pins should have prevented the landing gear itself from retracting while technicians tested the system.
Investigators found that pins had been installed on both main landing-gear assemblies. The nose-gear locking pin, identifiable by its red warning flag, had not been fitted.
When technicians moved the gear lever, the nose landing gear retracted and the front of the aircraft dropped onto the apron.
The interim report does not say why the nose-gear pin was left in the storage box or assign blame to any individual.
The aircraft was at FRA preparing to operate as Lufthansa Flight LH450 to Los Angeles International Airport (LAX) when the collapse occurred at about 12:45 local time.
No passengers had boarded, but technicians, flight crew, cabin crew and ground staff were inside the aircraft. The BFU said 28 people were on board and six others were directly involved outside. Several people suffered injuries.
Lufthansa initially said two cabin crew members and employees of service providers required hospital treatment.
Video of the accident showed the nose wheels moving forward as the gear folded, sending the aircraft’s nose crashing onto the pavement. A ground worker standing nearby moved away moments before the nose fell.
The accident closely resembles a 2021 incident involving a British Airways Boeing 787-8 at London Heathrow Airport.
In that case, technicians were also conducting a maintenance procedure that required them to cycle the landing gear. A locking pin was installed, but the engineer inserted it into an adjacent hole rather than the correct downlock position.
The UK Air Accidents Investigation Branch found that the incorrect hole could provide tactile and audible indications that made the pin appear properly installed. The nose gear retracted when technicians selected the landing-gear lever to the up position.
The Lufthansa accident differs in one important respect: investigators did not find the nose-gear locking pin in the wrong hole. They found it inside its storage box.
The BFU has not said whether the two accidents share deeper procedural or human-factors issues.
D-ABPQ was one of Lufthansa’s newest aircraft. Boeing delivered the 787-9 in January 2026, and it entered commercial service the following month.
The collapse caused substantial damage and forced Lufthansa to cancel the Los Angeles flight. The airline has not publicly set a date for the aircraft to return to service.