The US FAA will propose that operators of twin-aisle aircraft powered by Pratt & Whitney PW4000 series turbofan engines begin performing periodic inspections on certain sections of the engine.
The proposed airworthiness directive (AD), to be issued 25 March, comes in response to 294 reports citing cracks in the rear drum locking and loading slots of drum rotor disks in the high pressure compressor (HPC) section of the engine, says the FAA.
"We determined that the cracks resulted from thermal mechanical fatigue," says the agency, adding that the cracks could cause the rotor disk to rupture and damage the aircraft.
If approved as written, the AD will require operators to perform inspections any time the turbine blades attached to certain rotor disks are removed during maintenance shop visits.
The FAA notes that the inspections are considered an interim action pending a possible future rulemaking to address the root problem.
The agency says 1,038 engines are affected by the proposed AD. The engines power widebody aircraft including the Boeing 777, Airbus A330-200 and McDonnell Douglas MD-11.