United Boeing 777 engine damage consistent with metal fatigue: NTSB

WASHINGTON (Reuters) – United States National Transportation Safety Board (NTSB) Chairman Robert Sumwalt said on Monday that damage to a fan blade from a Pratt & Whitney engine that failed in a United Airlines Boeing 777-200 is compatible with metal fatigue, according to a preliminary assessment.

At a press briefing, Sumwalt said it was not clear whether Saturday’s PW4000 engine failure with a “loud bang” four minutes after takeoff was consistent with another engine failure on another flight. United to Hawaii in February 2018, attributed to fatigue. fracture in a fan blade.

The engine that broke down on the 26-year-old Boeing Co 777 and lost parts over a suburb of Denver was a PW4000 used on less than 10% of the world’s 777 widebody fleet.

In another incident on Japan Airlines (JAL) 9201.T 777 with a PW4000 engine in December 2020, the Transportation Safety Board of Japan reported finding two damaged fan blades, one with a metal fatigue crack. An investigation is underway.

The focus is more on engine maker Pratt & Whitney and analysts expect little financial impact on Boeing, but the PW4000 issues pose a new headache for the aircraft maker as it is recovering from the much more serious 737 MAX crisis. Boeing’s flagship narrow-body aircraft was grounded for nearly two years after two fatal crashes.

The fan blade of the United motor will be examined on Tuesday after being transported to a Pratt & Whitney laboratory where it will be examined under the supervision of investigators from the NTSB.

“What’s important is that we really understand the facts, circumstances, and conditions surrounding this particular event before we can compare it to any other event,” Sumwalt said.

Boeing has recommended airlines suspend aircraft use while the FAA identifies an appropriate inspection protocol, and Japan has imposed a temporary flight suspension.

The Federal Aviation Administration plans to issue an Emergency Airworthiness Directive soon that will require intensified fan blade inspections for fatigue.

The FAA in March 2019 after the February 2018 engine failure United attributed to fan blade fatigue ordered inspections every 6,500 cycles. A cycle is a takeoff and a landing.

Sumwalt said the United incident was not considered an unconfined engine failure because the containment ring contained the parts as they took off.

There was minor damage to the plane’s body, but no structural damage, he said.

The NTSB will look into why the engine cowl separated from the plane and also why there was a fire despite indications that the engine fuel was cut, Sumwalt added.

Pratt & Whitney, which is owned by Raytheon Technologies Corp, said Sunday it was coordinating with regulators to review inspection protocols.

Nearly half of the global fleet of 128 aircraft operated by airlines such as United, JAL, ANA Holdings, Korean Air and Asiana Airlines had already been grounded amid falling travel demand due to the pandemic coronavirus.