Boeing moved to cover 777 engines instead of a recent failure

Given that there were a number of possible flaws in possible modifications to the 777 exterior engine cover, commonly known as cowlings, “Boeing has decided to redesign the fan pit rather than trying to change existing fan vows to address concerns about “structural strength” and moisture issues, according to an FAA internal document reviewed by the Wall Street Journal.

“Boeing will manufacture a new fan hood and provide service instruction to operators to remove and replace the fan cubes,” according to the document, part of routine use on August 6, 2020, update on ongoing efforts at Seattle area offices. . Boeing and the FAA declined to comment on the status of the engine cover plan Wednesday.

Such alterations to aircraft parts may require years of design, testing and regulatory approval. Some aviation safety experts and regulators have become increasingly concerned about whether engine cover is strong enough to withstand the impact of a fan blade breaking off and burning out on flights.

Although rare, such damage to engine cover has appeared in a handful of recent engine failures. Pilots train to take down a plane operating on a single engine, which can be done safely, but large pieces of metal from the covers of other parts of the aircraft –– and passengers –– can endanger. The engine testing process for that capability has not been fully described, according to some safety experts and reports from the National Transportation Safety Board.

Jim Hall, chairman of the NTSB from 1994 to 2001, said recent events should have encouraged regulators to look “very aggressively” at engine coverage issues.

“I still don’t see any sign of this being done,” he said.

Boeing said it would continue to follow FAA guidelines on 777 engine covers, and was “engaged in ongoing efforts to introduce safety and performance improvements throughout the fleet.”

An FAA spokesman said reducing the risk of engine fan failure that could cause cowling damage is a priority – the focus of organizations after the 777 incidents in 2018 and this week. went. FAA officials have said the group was working with Boeing on a design change for a different-type engine that failed on a 2018 Southwest flight – killing a passenger – and -examine the need for modifications to other engines.

“Any proposed design change to an essential piece of structure must be carefully modified and tested to ensure that it provides an equivalent or improved level of safety and does not involve unforeseen hazards,” a spokesman for the group said.

The 777 engine failure last weekend came shortly after the plane – as happened in one of the 2018 events, operated by United – took off from Denver International Airport. A weakened fan-like blade broke and appears to have peeled a second blade around halfway, according to the NTSB, which is leading the investigation. The engine cover was ripped off, leaving a scrap of debris in the city below.

It was like two recent failures of some Pratt & Whitney-made engines on a subset of Boeing 777 –– 2018 United flights and one in December 2020 operated by Japan Airlines Co. authorities. in the U.S. and Japan that both provided fan blades that covered engine and battery.

In all three cases, the planes landed safely with no injuries.

Following the 2018 failure of the United 777, the FAA mandates that fan blades on the type of engine involved in a special “thermo-acoustic image” study –– use sound waves to signal cracks –– every 6,500 flights. The engine that failed over the weekend had flown about 3,000 flights since its last inspection, according to people familiar with the matter.

The FAA on Monday ordered an instantaneous thermo-acoustic image inspection for fan blades on some Pratt & Whitney engines on some Boeing 777 jets. Pratt & Whitney is a unit of aerospace company Raytheon Technologies Corp.

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But design change to secure engine covers is a longer and more involved process. The FAA document inside said Chicago-based Boeing had presented their 777 engine cover results to FAA experts in the Seattle area in early August.

Aircraft engines are expected to have broken fan blades and other metal parts and their protective covers, preventing them from damaging structures needed to keep the aircraft aloft. Unattached engine covers that do not fall to the ground could create aerodynamic drag, safety experts said. That could increase fuel consumption if the plane is not flying as efficiently, a concern for long-haul flights over water with few options for emergencies, said one of these experts. The FAA document identifies “fuel harassment” as a potential safety risk.

Engine certification tests have focused on ensuring that broken fan blades do not burn out the engine side and puncture the aircraft fuselage. Less attention was paid to the expectation that a blade could burn forward and damage the front part of the engine cover. These covers do not need to be attached during tests on how engines deal with broken fan blades so that the blades are visible.

“When you lose big pieces like that, that’s a risk,” said Jeffrey Guzzetti, former director of the FAA’s accident investigation department. “It’s never been like this before – it’s never been so big.”

Write to Andrew Tangel at [email protected] and Alison Sider at [email protected]