A Jetstar Boeing 787 was forced to return to Singapore’s Changi Airport after debris from a shredded tyre damaged a wing and caused flaps to malfunction.
The plane was headed to Melbourne with 231 passengers and 11 crew on board when the pilots received an alert that the wing flaps were not retracting evenly.
Flaps are moveable flight surfaces on the wing designed to increase lift at lower speeds during landing and take-off. The forces affecting an aircraft become unbalanced if the flaps on both wings do not deploy and retract together.
An Australian Transport Safety Bureau report into the May 13, 2017 incident found the left wing flaps were unable to move due to damage to a “torque tube” broken when debris from the tyre smashed through a panel on the underside of the wing.
The damage caused a misalignment with the right wing flaps, prompting the aircraft to shut down the flap drive system and generate a fault message.
The pilots notified air traffic control, put the jet into a holding pattern at 6000ft and decided to return to Singapore, opting not to dump fuel because of the proximity of other aircraft.
This was in accordance with procedures the Jetstar crew were following to land the aircraft safely.
“While the crew did not know about the tyre damage, the aircraft protective systems and crew actions allowed for a safe return and landing, despite the aircraft being overweight and at a higher than normal landing speed,’’ the report said.
The ATSB found the flap problem was a result of the delamination of the number 6 wheel tyre, likely at the southern end of runway 20C when the wheel was at high speed.
This gave the debris sufficient energy to penetrate the underwing panel, break the torque tube and interrupt the flap drive system.
The incident occurred before the tyre reached its expected service limit and the manufacturer concluded it had operated on an “aggressive” surface such as a grooved runway. It found the tyre experienced wear on the shoulder which led to cracking and undercutting of the tread.
The tyres had been certified as inspected according to the manufacturer’s requirements ahead of departure but no faults were recorded.
Nonetheless, Investigators said it was possible the tread was already damaged before departure.
“The arrival inspection likely occurred during daylight hours, but the aircraft may have been parked with the tyre tread positioned such that the initiation site was not visible to the inspector,’’ the report said “However, this was not confirmed by the ATSB.”
Jetstar has told its pilots and engineers to pay particular attention to the shoulder area of B787 tyres during inspections.