Pratt & Whitney training cited in 2018 United jet engine failure

A fan blade on a United Airlines Holdings Inc. jet engine that snapped off in flight in 2018, showering the plane with shrapnel, had shown signs of cracking that were missed in previous inspections.

The U.S. National Transportation Safety Board on Tuesday released a final report on the Boeing Co. 777-200 engine failure, concluding Raytheon Technologies Corp.’s Pratt & Whitney division didn’t create adequate test standards.

Inspections of the fan blade that failed—using technology to spot imperfections within the titanium structure—had shown evidence of weakening metal in 2010 and 2015, but an inspector attributed them to the way they were painted, the NTSB concluded.

Because the company had designated the inspections as a new and emerging technology, it never created specific training for inspectors or certified how they performed the work, the NTSB added. The engine was a Pratt & Whitney PW4077.

The incident on a flight from San Francisco to Honolulu on Feb. 13, 2018, was one of several in recent years raising safety concerns about how engines are designed.

The NTSB last November called on aircraft manufacturers to strengthen the material at the front of jet powerplants after debris on a Southwest Airlines Co. flight in 2018 blew into a window, causing the death of a woman. That engine was made by CFM International Inc., a joint venture between General Electric Co. and France’s Safran SA.

A critical safety measure on engines is that they’re designed with armored cases that are supposed to prevent debris from escaping during a failure. In both the United and Southwest accidents, debris caromed forward of the protective layer, causing extensive damage.

Metal fragments on the United plane struck the fuselage, wing and tail sections. The jet flew about 120 miles (193 kilometers) to Honolulu on a single engine and landed safely.

Pratt & Whitney said in an emailed statement that it had taken several corrective actions to address the cause of the failure. After the incident during the San Franciso to Hawaii flight, the company re-inspected all 9,600 fan blades and didn’t find any others with potential safety problems, the NTSB said.

The Federal Aviation Administration regulates companies such as Pratt & Whitney that perform inspections of aircraft parts.