Airlines, regulators ground PW4000-powered Boeing 777

United Airlines Boeing 777-222, powered by Pratt & Whitney PW4077 engines. Photo: © Colin Brown

The US Federal Aviation Administration (FAA) has issued an Emergency Airworthiness Directive for Boeing 777 aircraft powered by the Pratt & Whitney PW4000 engine, in the wake of the incident on United Airlines UA328 on 20th February.

Following the announcement, United Airlines has said it will voluntarily ground its fleet of 24 PW4000 powered Boeing 777s as “an abundance of caution”. The airline is the only operator of PW4000-powered 777 in the United States. Furthermore, ANA and Japan Airlines have removed the affected aircraft from their schedules. A total of 32 Boeing 777 are now grounded in the east-Asian nation. On Monday, nearby South Korea followed and also grounded airplanes with the engine.

In a statement issued by the FAA, the airworthiness directive is to “require immediate or stepped-up inspections of Boeing 777 airplanes equipped with certain Pratt & Whitney PW4000 engines”. At present, an investigation into the catastrophic engine failure on flight UA328 is ongoing and the cause is undetermined.

A few hours later, aircraft manufacturer Boeing issued a statement recommending operators of PW4000-powered 777s to temporarily remove the aircraft from service until the FAA has finalized an inspection protocol. According to the company, there are 69 affected aircraft currently in service and another 59 in storage.

The Emergency Airworthiness Directive (EAD) comes as a result of the incident involving UA328 not being an isolated incident. United Airlines flight UA328 is the fourth catastrophic failure of a Pratt & Whitney PW4000 engine fitted to a Boeing 777 in five years, three of which have occurred to aircraft operated by United Airlines.

In June 2016, United UA328 (coincidentally the same flight number as the February 2021 incident) experienced a bird strike upon take off, which resulted in the grass along the runway catching fire. In 2018, the number 2 engine of UA1175 had an uncontained fan blade failure, whilst en-route to Honolulu. On 4th December 2020, a Japan Airlines Boeing 777 (flight JL904) suffered a similar uncontained engine failure in one of its PW4000 engines, whilst travelling to Tokyo from Okinawa.