EASA today issued an emergency Airworthiness Directive related to Pratt & Whitney Geared Turbofan engines on A320neo family aircraft. That AD can be found here, Apparently, several rejected take offs (RTO) and in flight shut downs (IFSD) have occurred with the PW1127G-JM, PW1127GA-JM, PW1133G-JM and PW1133GA-JM engines having engine serial numbers P770450 or subsequent.
While the root cause is not known, preliminary findings indicate that the affected engines, that had a high pressure compressor aft hub modification that began with serial number 450, are more susceptible to IFSD, which if not corrected could lead to dual engine failure. Pratt & Whitney indicate that the issue is related to a “knife-edge seal in the high pressure compressor aft hub” and are already at work to find the root cause and fix for that issue.
Emergency operational restrictions called for in the Airworthiness Directive include de-pairing affected engines within 3 flight cycles, and within 1 flight cycle eliminating ETOPS operations for aircraft with 1 affected engine installed.
This Airworthiness Directive presents another blow to the GTF program just as production rates had ramped up to planned levels. It appears that because this AD impacts newer engines, Pratt & Whitney will need to stop production to modify the current build standard and fix the cause behind the higher than expected IFSD rate.
At this writing, we cannot project how long it will take for Pratt & Whitney to develop a “fix” for the problem, nor the overall impact on A320neo operations with affected customers. This AD will likely impact about 226 engines on 113 aircraft in service with 18 customers. It is also likely to impact a few more engines currently on the production lines at Airbus and Pratt & Whitney that will likely need to be retrofit prior to installation on new aircraft, as well as spare engines in inventories.
As we obtain further details, we will update this story.
© 2018, Ernest S. Arvai. All rights reserved.