The Federal Aviation Administration (FAA) has issued a proposed airworthiness directive (AD) for the problem-plagued Pratt & Whitney PW1100G engines that power Airbus A320neo-family aircraft.
The AD, for which it is soliciting comments until mid-November, would require all operators of the PW1100G family of turbofan engines to replace the main gearbox assembly and electronic engine control software. Those engines include PW1133G-JM, PW1133GA-JM, PW1130G-JM, PW1129G-JM, PW1127G-JM, PW1127GA-JM, PW1127G1-JM, PW1124G-JM, PW1124G1-JM, and PW1122G-JM models.
“This AD was prompted by multiple reports of in-flight engine shutdowns as the result of high-cycle fatigue causing fracture of certain parts of the main gearbox (MGB) assembly,” the FAA says in its proposal due to be published in the Federal Register on 4 October. “The FAA is issuing this AD to prevent failure of the MGB assembly. The unsafe condition, if not addressed, could result in failure of one or more engines, loss of thrust control, and loss of the airplane.”
The proposed AD would supersede interim AD 2019-11-08, issued in June, which imposed this requirement on all engines that operate on 180-minute and 120-minute extended-range twin-engine operational performance standards, or ETOPS flights. ETOPS is a rule which permits twin engine aircraft to fly routes which, at some point, is more than 60 minutes flying time away from the nearest airport suitable for emergency landing.
“The FAA is proposing this AD because it 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,” the document says. The FAA adds that it estimates that the proposed AD affects 72 engines installed on airplanes of US registry.
The proposed AD would require replacement of the affected MGB assembly at the next engine shop visit after the AD’s effective date for engines that do not operate on ETOPS flights.
Pratt & Whitney says in a statement that it is working in coordination with Airbus, the regulatory authorities and airline customers “to incorporate upgrades improving the reliability of the accessory gearbox in the PW1100G-JM fleet.”
“The accessory gearbox is external to the engine and drives accessories such as pumps and generators. We have certified engine hardware and software improvements to address the issue, and fleet implementation is progressing well. We are committed to supporting our customers to ensure minimal disruption and are confident that the upgrades will be completed within the required timeline,” the engine manufacturer says on 3 October.
The turbofan engines have a history of issues since the model was rolled out in early 2016. Most recently, in November 2016, the FAA ordered airlines to replace components in the compressors and turbines of PW1100Gs turbofans. The directives addressed corrosion concerns and issues with the engine's "knife edge seal" – the same seal that caused several inflight shutdowns earlier in 2018. The shutdowns prompted a grounding of PW1100G-powered A320neos. A second directive ordered airlines to replace the "front hub" of PW1100G high-pressure compressors – a measure that came in response to a corrosion report.
In the USA, only Hawaiian and Spirit Airlines operate PW1100G-powered A320neo-family aircraft, according to Cirium fleets data. Airlines worldwide operate 459 Airbus narrowbodies with PW1100Gs, Fleets Analyzer shows.
Airbus also offers A320neo-family aircraft powered by CFM International Leap-1A turbofans.