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FAA Orders Emergency Inspection on Pratt & Whitney PW4400 Engines

After the engine explosion of United Flight 328, The Federal Aviation Administration is demanding every airline operating aircraft with the Pratt & Whitney performs an emergency inspection before they carry passengers again. The inspections must include a thermal acoustic image inspection of the hollow fan blades.

The Federal Aviation Administration is ordering all aircraft powered by the Pratt & Whitney PW4400 engine to be grounded until they can go through a thorough inspection. The emergency airworthiness directive came down from the agency on Tuesday, Feb. 23, 2021.

PW4400 Inspection Order Directly Related to United Flight 328 Incident

The Pratt & Whitney PW4000 family of hi-bypass turbofan engines was first introduced to the market in 1984 as a replacement to the JT9D engine used on the Boeing 747-100. The FAA certified the powerplant for use two years later, with variations used on a number of different aircraft. The Airbus A300, A310 and A330 have all used variations of the engine, along with the Boeing 747-400, 767 and the 777.

In the last five years, the PW4400 engine was to fault in at least four commercial aviation incidents, including two on United Airlines flights. In 2018, another Boeing 777 operating United Airlines Flight 1175 experienced a fan blade failure, causing the inlet and cowl to fall from the aircraft around 45 minutes after departure. An investigation by the National Transportation Safety Board discovered a cracked engine blade was wrongly returned to service, which ultimately lead to the failure.

In the FAA order, airlines that have aircraft powered by the PW4400 engines must conduct a thorough inspection of the powerplants before they start flying again. This must include a thermal acoustic image inspection of the hollow fan blades, which can help to detect cracks located within the blades, that cannot be seen by the naked eye.

“As these required inspections proceed, the FAA will review the results on a rolling basis,” the agency noted in a written statement. “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.”

Investigation Continues on Engine Failure from United Flight 328

While air operators are required to inspect engines before they start flying again, the NTSB is continuing their investigation on the chain of events that lead to the PW4400 engine exploding while United Flight 328 was in the air. Their research is not expected to be completed for several months.

Discuss the United Flight 328 incident on the FlyerTalk forums.

Feature image courtesy: Ronidong/Wikimedia Commons/CC-BY-4.0