The September 11 failure of a GE GEnx engine on an Air Bridge 747-8 freighter was not caused by a cracked fan mid-shaft (FMS), NTSB reported Thursday. Since NTSB is merely a party to the Civil Aviation of China's (CAAC) investigation into the Shanghai incident (and therefore not the organization designated to provide official updates), the news was delivered via an update on the July 28 failure of a General Electric GEnx engine on a 787 undergoing taxi testing in Charleston, S.C., which was traced to an FMS fracture. Said NTSB:
The Air Bridge incident triggered urgent recommendations from NTSB on September 14 to inspect GEnx FMSs. While NTSB's recommendation letter cautioned that an inspection of the Shanghai incident engine was still pending, the board hedged its bets that the the engine suffered a similar fate as the Boeing test engine in Charleston:
As part the CAAC's investigation and in relation to the NTSB's ongoing investigation of the July 28th engine failure, preliminary findings from the examination of the Shanghai incident engine revealed that the FMS was intact and showed no indications of cracking. The examination and teardown of that engine is continuing under the direction of the CAAC.
[P]hotographs of the LPT show damage that is similar to that which was observed on GEnx-1B engine ESN 956-121 at Boeing in Charleston. Although other failure modes could cause an N1 rollback and broken blades, the damage noted on the photographs of ESN 959-228 is consistent with that observed on the engine that failed at Charleston.And on the probes go....