The FAA issued an
Emergency Airworthiness Directive (AD) (PDF) tonight that requires U.S. operators of airplanes equipped with certain Pratt & Whitney PW4000 engines to inspect these engines before further flight.
The FAA is taking this action as the result of a fan-blade failure that occurred Saturday on a Boeing 777-200 that had just departed from Denver International Airport. Although the aircraft landed safely, the failure resulted in damage to the engine, an in-flight engine fire, and damage to the airplane.
After reviewing the available data and considering other safety factors, the FAA determined that operators must conduct a thermal acoustic image (TAI) inspection of the large titanium fan blades located at the front of each engine. TAI technology can detect cracks on the interior surfaces of the hollow fan blades, or in areas that cannot be seen during a visual inspection.
As these required inspections proceed, the FAA will review the results on a rolling basis. Based on the initial results as we receive them, as well as other data gained from the ongoing investigation, the FAA may revise this directive to set a new interval for this inspection or subsequent ones.
The previous inspection interval for this engine was 6,500 flight cycles. A flight cycle is defined as one takeoff and landing.
This AD is effective immediately upon receipt. The FAA will share this information with other international civil aviation authorities.
At least three PW4000s have failure in recent years, including the United 777-200 incident referenced above.
Earlier this week, Boeing called for the global grounding of all 777s equipped with particular engine model.
United Airlines is the only U.S. carrier to use this engine. The company has removed nearly two dozen of the aircraft from service.
Japanese regulators have also ordered the planes grounded, impacting 128 777s.
