Airbus decided to stop accepting additional Pratt & Whitney PW1100G engines equipping its A320neo family aircraft, after a higher than normal number of inflight shutdowns and aborted takeoffs were reported on aircraft using the latest build-standard engines.

The problem involves the knife-edge seal in the high-pressure compressor aft hub and can potentially appear on engines starting with serial number P770450. 33 aircraft, according to Airbus and the European Aviation Safety Agency (EASA).

Airbus says around one-third of the in-service fleet of A320neos and A321neos has those engines installed so far, 11 of which are understood to have all two engines of the problematic standard and 21 just one of them.

Pratt & Whitney had no immediate comment on the latest Airbus decision.

The problem could become much bigger if the engine supplier cannot find a quick fix, as the delivery schedule of future A320neo aircraft will likely be seriously affected in that case.

The issue is the latest in a string of problems that have bedeviled the GTF program.

The A320neo’s planned 2015 entry into service was pushed into 2016 because of GTF issues, and both Airbus and Bombardier have blamed Pratt for A320neo-family and CSeries aircraft delivery delays as Pratt & Whitney struggled to ramp up production as fast as needed and as fixes to address reliability and durability shortfalls were simultaneously introduced. According to Pratt & Whitney, the latest issues do not involve engines for the Embraer E2 family and the Bombardier CSeries, but are limited to the Airbus application.

The exact consequences of the Airbus decision are not yet clear, partly because the spare pool of PW1100G may include an unidentified number of engines that need no modification and can therefore be used. But Airbus has still parked around 30 otherwise completed aircraft at its manufacturing sites in Toulouse and Hamburg awaiting engines.

EASA on Feb. 9 issued an emergency airworthiness directive (EAD), warning of a potential “dual engine” inflight shutdown on A320neo-family aircraft powered by Pratt & Whitney PW1100G geared turbofan (GTF) engines. Industry sources say a total of four such incidents or inflight shutdowns have been reported so far, but the actual number could be higher.

A Pratt spokesperson said the issue relates to a “limited sub-population” of PW1100G engines.

The EASA said that “several occurrences of inflight shutdown and rejected takeoff have been reported on certain” A320neo-family aircraft powered by GTF engines.

There are 113 A320neo family aircraft powered by the Pratt engines in service (the CFM Leap-1A engine is also an option on A320neo-family aircraft). Both A320neos and A321neos are affected.

EASA said aircraft with two affected engines can only operate three more cycles before one of them has to be replaced with a substitute that does not have the HPC aft hub issue. It is also said extended-range, twin-engine operations (ETOPS) can only be performed with two unaffected engines. Airbus has issued an Alert Operators Transmission (AOT) providing instructions “to de-pair the affected engines and discontinue [ETOPS] for aircraft fitted with affected engines,” according to EASA.

Neither the aircraft manufacturer nor the agency disclosed what airlines are operating aircraft with affected engines. However, Indian LCC IndiGo confirmed it has grounded three A320neos after the EASA EAD was issued.

“We have identified the potentially affected engines and communicated with our customers,” the Pratt spokesperson said. “As a precaution, aircraft with these engines will be addressed in a manner consistent with the operational instructions issued by Airbus, and coordinated between Airbus and Pratt & Whitney as needed.”

Airbus said in a statement that Pratt is “investigating the root cause of this new finding with the full support of Airbus.”

 Jens Flottau,,

Aaron Karp,