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Two downlock pins that had not been removed from a Boeing 787’s main landing gear following towing, nor identified during subsequent pre-flight inspections, prevented the aircraft’s main landing gear from retracting after take-off, an Australian Transport Safety Bureau investigation report outlines.
On 21 June 2021, the Qantas Boeing 787-9 departed Sydney for Perth with 106 passengers and 13 crew on board.
During the initial climb, when the flight crew selected UP on the aircraft’s landing gear lever, they received a warning indicating that neither main landing gear had retracted to the ‘up and locked’ position.
Actioning the aircraft’s electronic checklist did not resolve the issue.
The flight crew then selected the landing gear lever to DOWN, resulting in a positive gear extension indication, and the aircraft was returned to Sydney for an uneventful landing.
Subsequent inspections identified that two of the aircraft’s five landing gear downlock pins had not been removed after it had been towed to the domestic terminal aircraft bay in preparation for the flight.
The pins prevented the main landing gear from retracting after take-off.
“Pins are inserted into the nose and main landing gear when the aircraft is on the ground to prevent inadvertent gear retraction during maintenance or towing,” ATSB Director Transport Safety Stuart Macleod explained.
“In this case two of the pins – one of the two for each main landing gear – had not been removed after towing and prior to the flight. In addition, subsequent preflight inspections by the flight and dispatch crew did not identify that the pins remained in place prior to departure.”
Attached to each pin was a red ‘remove before flight’ streamer. One streamer on each main landing gear was visible in CCTV footage of the aircraft being towed to its bay prior to the flight.
The pins attached to these two streamers were removed before departure, while the second gear pin on each main landing gear was missed. The missed gear pin streamers may have been stuck on the gear, from a combination of grime and the recent wet and windy conditions.
Post-incident inspection found all four main gear pins’ streamers to be in place, but dull and frayed. Their condition prior to the flight could not be conclusively determined.
“‘Remove before flight’ streamers are visual reminders to remove covers and lockout devices prior to flight, but can be subject to varying environmental conditions that can reduce their visibility,” Mr Macleod said.
“Expectation can also affect your ability to identify these warning devices. If you are not expecting to see a ‘remove before flight’ streamer, you are significantly less likely to detect one that is present.
“The same principle can also prevent the discovery of damaged and/or missing components.”
The 787 has five landing gear pin locations: one in its nose gear, and two in each of its main landing gear, whereas other types in the Qantas fleet such as the A330 and 737 have three pins: one in the nose gear, and just one in each of the main landing gears.
The two members of the tow crew who had removed three of the five gear pins – one from the nose gear, and one each from the left and right main landing gear – had not towed a 787 prior to the occurrence.
Moreover, once removed, on the A330 and 737 the gear pins are stored on the flight deck, whereas on the 787 they are stored in the aircraft’s electrical equipment centre (EEC), just aft of the nose gear.
When stowing the three removed gear pins in this incident, the tow crew team member reached up from a ladder below, and so was unable to see inside the stowage compartment, where there were receptacles for five gear pins in total.
After the occurrence, Qantas advised it was working to relocate the gear pin stowage on its 787s to the flight deck, to bring them in line with other aircraft in its fleet, and to enable ease of access to verify pin stowage.
The operator also distributed a memo to its engineering, flight and ramp staff to highlight the quantity and location of the gear pins on the Boeing 787, and the importance of following the documented ramp, pre-flight and dispatch procedures.
The memo also emphasised the importance of checking the pin locations, rather than relying on ‘remove before flight’ streamers for identification of pins, after towing.
Read the report: Landing gear retraction deactivation and return involving a Boeing 787, VH-ZNH, near Sydney Airport, New South Wales, 21 June 2021