The ongoing probe into the October 2019 failure of a GE Aviation GE90-115B on a Thai Airways 777-300ER prompted GE to recommend immediate removal of parts from 16 specific engines, and the FAA mandated the move in a Jan. 17 emergency airworthiness directive.
GE’s service bulletin (SB) and the related FAA mandate target high-pressure turbine (HPT) interstage seals in the affected engines. GE recommended inspections or removals of the affected parts. The FAA mandate—which applies only to U.S.-registered aircraft but is expected to be adopted by other regulators, calls for them to be removed within five flight cycles. GE’s inspection discussed in the SB is a possible alternate means of compliance, with regulatory approval.
“GE Aviation is working in close coordination with our customers and regulatory authorities to inspect or replace high-pressure turbine interstage seals on a limited population of GE90-115B engines,” the company said. "GE has proactively contacted impacted customers and is deploying resources and technical teams to assist them with the recommended action.”
The emergency directive is the second targeting a subset of interstage seals based on information gleaned from the Thai incident. The first AD, issued just after the Thai failure, targeted eight engines. The probe is still going.
The Thai Airways aircraft was departing Bangkok for Zurich when the crew rejected the takeoff at low speed. Debris damaged the aircraft’s fuselage and the other engine. No injuries were reported.
A source with knowledge of the findings told Aviation Week that the new directive affects engines at Thai and one other carrier. The link between the engines is a regular mission profile that includes short flights, short runways, minimal taxi time and fast turnaround times.
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