Pratt-Powered 777s Could Be Parked for Months on Lengthy Checks

(Bloomberg) -- Boeing Co. 777 jetliners with the type of Pratt & Whitney engine that broke apart over Denver on Saturday could remain parked for an extended period -- possibly months -- while the engine-maker completes rigorous inspections demanded by U.S. air-safety regulators.

It will take eight hours to inspect each one of the 44 engine fan blades on each jet with high-tech, elaborate checks needed to spot potential imperfections that could cause them to break apart in flight, Federal Aviation Administration Administrator Steve Dickson said Wednesday in a Bloomberg TV interview.

“We’re going to undertake that campaign on the entire fleet, and then as the blades are inspected then the airplanes will begin to be returned to service,” Dickson said.

With 22 fan blades on each engine, that translates to 352 work-hours per plane or 44 eight-hour shifts. Depending on the capacity at Pratt & Whitney’s facility performing the inspections, it could take months to complete the required checks on the roughly 125 older 777 twin-aisle planes affected by the order. United Airlines Holdings Inc. is the largest operator of the affected 777s, with roughly 50 in its fleet, half of which are in storage.

The extensive nature of the inspection work could alter United’s views about whether to retire the jets. The newest of those was delivered in May 1998 and has been parked at a storage center in Roswell, New Mexico, since March, according to Cirium data. It’s also unclear how costs associated with the inspections would be handled between United and Pratt & Whitney, a unit of Raytheon Technologies Corp.

A United spokesman said the carrier had no immediate comment on the issue. A Pratt & Whitney representative declined to comment.

Fan blades from the affected engines -- Pratt & Whitney PW4000 engines with 112-inch diameter fans -- must be removed and shipped to a Pratt facility on its headquarters campus in East Hartford, Connecticut, the company has said.

Technicians inspect the blades for tiny cracks using so-called thermal acoustic image inspections that are similar to an ultrasound for use in medicine. The blades are bathed with sound waves that cause the metal to vibrate, which is then inspected for any minute differences in friction and heat that would reveal even tiny cracks beneath the blade’s surface.

The FAA mandated the rigorous checks in an emergency order issued after a fan blade broke off inside one of two Pratt & Whitney PW4000 engines powering a 777-200 operated by United over Colorado last weekend. The plane landed safely and no passengers or crew were hurt.

Crash investigators have pointed to preliminary signs that metal fatigue caused a crack to form in the blade that failed, which broke off during flight and severed a second fan blade and spewed metal debris on a suburban neighborhood.

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