WASHINGTON—The U.S. FAA, moving quickly to adopt Pratt & Whitney’s recommendations, is ordering engine inspections on some Airbus A220 and Embraer E190-E2-series aircraft within 50 cycles—or about a week—based on findings from two recent Swiss International PW1524G-3 failures.
The airworthiness directive, set to be published Sept. 26 and effective immediately, calls for repetitive borescope inspections of PW1500G and PW1900G-series low-pressure compressor (LPC) stage 1 rotors (R1s) and inlet guide vanes. The checks only apply to engines with fewer than 300 cycles since new.
The directive is based on Pratt service bulletins issued Sept. 23 and will likely be adopted globally. The FAA directive would affect Delta Air Lines, the only U.S. A220 operator.
Pratt issued its bulletins one week after an in-flight shutdown (IFSD) of a Swiss A220-300’s No. 1 engine while en route from Geneva International Airport to London Heathrow. A similar incident—same airline, aircraft type, and route—occurred July 25.
“These IFSDs were due to failure of the LPC R1, which resulted in the LPC R1 releasing from the LPC case and damaging the engine,” the FAA explained. “LPC rotor failures historically have released high-energy debris that has resulted in damage to engines and airplanes.”
Both aircraft landed without incident. The first diverted to Paris and the second returned to Geneva.
The second incident resulted in a hole in the LPC case and a separated R1, the U.S. NTSB said. In the first incident, the LPC R1 was “missing,” the board said.
The incidents’ similarities extend beyond the operator and equipment types. Both occurred as the flights were approaching cruise altitude—one at FL350 and one at FL320. Each engine had fewer than 300 cycles since new—the first engine failed at at 154 cycles, while the second had 230 cycles.
“Both failures of the LPC R1 occurred at low flight cycles since new,” the FAA said. “The manufacturer has recommended that these inspections occur within the next 50 flight cycles and the FAA has adopted that recommendation. Based on current operational usage of the affected airplanes, 50 flight cycles equates to approximately 7 to 10 operating days. Therefore, the FAA has determined that low flight-cycle rotors require inspections within the next 50 flight cycles from the effective date of this AD to prevent LPC R1 failures.”
If inspections turn up rotor cracks, damage that “exceeds serviceable damage,” or misaligned guide vanes, the LPC must be replaced.
Repetitive checks must be done every 50 cycles until the engine surpasses 300 cycles.
Pratt and FAA expanded the checks to PW1900Gs “because similarities in type design make these engines susceptible to the same unsafe condition,” the agency said.
NTSB was designated to lead the probes by France’s Bureau d’Enquêtes et d’Analyses pour la Sécurité de l’Aviation Civile and the Swiss Transportation Safety Board.