A mid-air engine shutdown aboard a Jetstar Airways Boeing 787-8 aircraft has been attributed to a known issue with the transfer gearbox (TGB) of the General Electric GENx-1B turbofan.

On 6 August 2016, the crew of flight JQ12 was operating a Tokyo Narita-Gold Coast service when they were alerted to a fault in the aircraft’s (VH-VKK) right engine, says the Australian Transport Safety Bureau in its final report into the incident.

The crew followed the checklist for this fault, but thirty minutes later there was an alert about low oil quantity in the engine. Following checklist procedures, the crew idled the engine and shut it down. They diverted to Guam, which was 370km from their position, where they made an uneventful single engine landing.

“When the engine cowls were opened for the initial inspection there was a large quantity of oil found throughout the engine and a considerable amount of metallic debris found within the engine oil system,” says ATSB.

Following a data download and analysis by GE Aviation, Jetstar opted to perform an engine change before returning the aircraft to service.

It was discovered that the housing of the transfer gearbox, which transmits engine speed to the accessory gearbox via a horizontal driveshaft, was fractured. GE Aviation determined that the damage was consistent with a known issue, as described in an earlier service bulletin. That called for TGBs to be replaced due to the potential for a gear fracture, resulting in engine oil loss and in-flight shutdowns, in certain scenarios.

Jetstar had been in the process of replacing TGBs across its fleet, but the aircraft in question was assessed to be at the lowest risk of experiencing an issue based on a number of service parameters.

The ATSB says that following the 6 August incident, the TGB modification schedule was amended, with modifications across its 787 fleet completed in November.

“This incident highlights the importance of flight crew complying with checklist actions when dealing with a fault condition,” adds the ATSB. “In-flight, the crew did not have knowledge of the extent of the damage to the engine TGB. However, by following their training and checklist procedures, they reduced the risk of a potential escalation of the fault.”

At the time of the incident, the aircraft was caring 309 passengers and 11 crew. Flight Fleets Analyzer indicates that it was delivered on 15 July 2015.

Jetstar operates 11 787-8s.

Source: Cirium Dashboard