Emergency airworthiness directive (AD) 2013-10-52 is sent to owners and operators of General Electric Company (GE) GE90-110B1 and GE90-115B turbofan engines.
This emergency AD was prompted by reports of two failures of transfer gearbox assemblies (TGBs) which resulted in in-flight shutdowns (IFSDs). Investigation has revealed that the failures were caused by TGB radial gear cracking and separation. Further inspections found two additional radial gears with cracks. This condition, if not corrected, could result in additional IFSDs of one or more engines, loss of thrust control, and damage to the airplane.
Relevant Service Information
We reviewed GE GE90-100 Series Alert Service Bulletin (ASB) No. GE90-100 S/B 72-A0558, Revision 1, dated May 14, 2013, and GE90-100 Series ASB No. GE90-100 S/B 72-A0559, dated May 14, 2013. The ASBs provide additional information regarding the affected TGBs.
We are issuing this AD because we evaluated all the relevant information and determined the unsafe condition described previously is likely to exist or develop in other products of the same type design.
This AD prohibits operation of an airplane with affected TGBs installed on both engines five days after receipt of this emergency AD.
We consider this AD to be an interim action. We anticipate that further AD action will follow.
More: see Full AD Attached
DATE: May 16, 2013
AD #: 2013-10-52
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General Electric Company (GE) GE90-110B1 and GE90-115B turbofan engines.