After two incidents in which engines shut down in mid-flight, Boeing Co. and General Electric Co. have warned 10 airlines of a possible mechanical problem with 777 passenger jets.

The companies have traced the problem to a faulty part in the transfer gearbox that causes an automatic shutdown in the 777’s GE-made engines. There are 26 airplanes in service with the engines and another 14 were in production at Boeing’s facilities in Everett, Wash.


The problem is due to a bad batch of parts made from September 2012 to March 2013 by GE supplier Avio of Italy. About 118 transfer gearboxes manufactured during the six-month period may be affected.

GE issued a bulletin to at-risk airlines that requires them to “detwin” the engines by making sure that only one of two engines has a transfer gearbox that could be affected.


The company is shipping replacement transfer gearboxes to customers.

“GE is working closely with both Boeing and the Federal Aviation Administration on this aggressive fleet action,” the company said. “This transfer gearbox model has been in operation with GE90 engines for almost 15 years with extremely high reliability over 40 million flight hours.”


The actions come in response to two in-flight engine shutdowns on 777 passenger flights when there was gear separation within the transfer gearbox. The first event occurred on a flight in February by Russian carrier Aeroflot. The second incident occurred last week on an Air China flight.

GE does not know the root cause: “Early analysis of transfer gearboxes has revealed a material anomaly, but no formal conclusions have been reached,” the company said.


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