After U.S. regulators announced additional inspections and Japan suspended their usage while taking further action, Boeing Co advised airlines to suspend the use of 777 jets with the same sort of engine that shed debris over Denver on the weekend.
The moves involving Pratt & Whitney PW4000 engines came after the right engine of a United Airlines 777 damaged on Saturday, dispersing its outer protective casing over a residential area.
United said the next day it would voluntarily and temporarily remove its 24 active planes, hours before Boeing’s announcement.
Boeing said 69 of the 777 aircraft with PW4000 engines were in operation and 59 were stored at a period when airlines had grounded aircraft due to the COVID-19 pandemic’s decline in demand.
The manufacturer instructed airlines to suspend operating them until the required inspection procedure was established by U.S. regulators.
It falls short of a mandatory global grounding but is another headache for the planemaker after its 737 MAX crisis and comes after criticism of U.S. Federal Aviation Administration (FAA) oversight regarding the 737 MAX.
The affected 777-200s and 777-300s are older and less fuel-efficient than newer versions, and only five airlines – United, Japan Airlines Co Ltd (JAL), ANA Holdings Inc, Asiana Airlines Inc, and Korean Air Lines Co Ltd. are currently operating. They’re mostly phasing them out of their fleets.
The problem concerns Pratt & Whitney, one of three engine makers originally involved in the 777, whose engines power less than 10% of the delivered fleet of more than 1,600 planes.
The National Transportation Safety Board (NTSB) said its initial examination of the 26-year-old plane indicated most of the damage was confined to the right engine, with only minor damage to the airplane.
It said the inlet and casing separated from the engine and two fan blades were fractured, while the other fan blades exhibited damage.
Pratt & Whitney, owned by Raytheon Technologies Corp, said it was coordinating with operators and regulators to support a revised inspection interval for the engines.
Japan’s transport ministry ordered JAL and ANA Holdings to suspend their use while it considered whether to take additional measures, acting before the FAA.
An official at South Korea’s transport ministry said it was waiting for formal action by the FAA before giving a directive to its airlines. The U.S. agency said it would soon issue an emergency airworthiness directive.
“Based on the initial information, we concluded that the inspection interval should be stepped up for the hollow fan blades that are unique to this model of engine, used solely on Boeing 777 airplanes,” the FAA said.