A United Airlines plane with a Pratt & Whitney engine that failed on Saturday February 20 had flown fewer than half the flights allowed by US regulators between fan blade inspections, two sources with knowledge of the matter said.
The Boeing Co 777 plane had flown nearly 3,000 cycles, equivalent to one take-off and landing, which compares to the checks every 6,500 cycles mandated after a separate United engine incident in 2018, said the sources.
They sought anonymity as they were not authorised to speak publicly. United declined to comment to Reuters.
Pratt, the maker of the PW4000 engines, advised airlines to step up checks to every 1,000 cycles, in a bulletin seen by Reuters. It did not immediately respond to a request for comment from Reuters.
The US Federal Aviation Administration (FAA) said that it was ordering immediate inspections of 777 planes with PW4000 engines before they could return to flight, going further than Pratt.
The engines are used on 128 older versions of the plane, accounting for less than 10% of the more than 1,600 777s delivered and only a handful of airlines in the United States, South Korea and Japan were operating them recently.
Japan and South Korea have also grounded the planes for fan blade checks.
The FAA acknowledged that after a Japan Airlines (JAL) PW4000 engine incident in December it had been considering stepping up blade inspections that use thermal acoustic imaging to find signs of metal fatigue.
A risk-assessment meeting was held last month to discuss the issue before the United engine failed on Saturday February 20, one of the sources said, confirming an earlier report by CNN. No decision had been imminent ahead of the United incident, the source added.
A spokesperson for Pratt, which is owned by Raytheon Technologies, said that fan blades will need to be shipped to its repair station in East Hartford, Connecticut, for the latest inspections, including those from Japan and South Korea.
Each engine has 22 blades that must be removed individually and each will take eight hours to inspect, FAA administrator Steve Dickson told Bloomberg TV.
That is the equivalent of 352 hours of work per plane, as each 777 has two engines. Boeing said that 69 of the planes were in active service before February 20's incident, while 59 had been grounded amid low demand during the pandemic.
Pratt did not respond to questions about how many engines it could inspect per month. United has not commented on how long it expects the inspections to take, while JAL and ANA Holdings said that the timing is unclear.
Boeing Planned To Replace 777 Engine Covers Before February 20 Failures
Boeing Co was planning to replace engine covers on its 777 jets months before the serious failures on February 20, The Wall Street Journal has reported, citing an internal US Federal Aviation Administration (FAA) document.
As mentioned above, the FAA ordered immediate inspections of 777s with Pratt & Whitney PW4000 engines before further flights, after an engine failed on a United Airlines 777 on Saturday February 20.
The plane maker and the FAA had been discussing potential fixes for approximately two years, following an earlier incident in 2018, according to The Wall Street Journal.
Boeing did not immediately respond to a request from Reuters for comment.
Although immediate attention has focussed on the engine's manufacturer, Pratt & Whitney, Reuters has reported that its cowling, or casing, is manufactured by Boeing.
Boeing has declined to comment on its manufacturing role and referred questions on the part to US air accident investigators.
The inspections affect older 777s fitted with Pratt & Whitney engines. Newer models, mainly powered by rival General Electric, are not affected.
United had bet on Boeing 777s for ramped-up flying in March
United Airlines had planned a big increase in flights on its Boeing 777-200 planes this month, according to data, suggesting that the grounding of the Pratt & Whitney-powered jets could create some scheduling headaches for the airline.
United was planning to use the large jets more in March on as it tries to tap into an expected bounce in leisure travel.
Numbers from aviation data firm Cirium show that United had scheduled 3,329 flights on wide-body planes in March, up 31% from February. Of those flights, 961 were scheduled on the now suspended 777-200, an 84% jump from their usage in February.
The suspension affects 52 planes. While United has dozens of narrow-body airplanes in storage due to the pandemic, it only has parked 48 wide-body planes with more than 190 seats, and none with as many seats as the 777-200, according to Cirium.
"As we continue working through updating our schedule based on aircraft availability, we will do so with the goal of impacting as few customers as possible," United spokesperson Leslie Scott said.
Last week, United warned its cargo customers of possible disruptions to its flight schedule in March as it juggles its fleet.
Even if flights are impacted by the 777-200 withdrawal, analysts said that the ramifications are likely to be far less severe than the grounding of Boeing's 737 MAX jets in 2019, which forced US airlines including United to cancel thousands of flights at a time when the industry was flourishing.
United has options to replace the 777-200, aviation analyst Robert Mann said, though they will vary according to the strength of advanced bookings and the timing of inspections ordered by the FAA.
Raytheon Technologies owned Pratt is handling the thermal acoustic inspections of the engine's fan blades, which showed signs of metal fatigue in preliminary assessments of the United incident, in a process expected to take around 352 hours of work per plane.
The start date and pace are unclear.
United, Japan Airlines Co Ltd (JAL) and ANA Holdings Inc are the main airlines with the affected planes.
JAL and ANA told Reuters that they have replaced the routes that were scheduled on those planes with different aircraft types and do not expect to cancel any flights.
United had the largest total inventory of PW4000-equipped aircraft, according to Cirium, which shows a total 843 aircraft in the airline's fleet, including a total 277 in storage.
While the 777-200s are among United's oldest, it had configured some of them to hold as many as 364 seats, more than any other in its fleet. Using 777s on leisure routes such as flights to Hawaii could allow the airline to book more revenue per flight by selling more economy seats on routes that typically do not draw many paid business class travellers.
Amid an overall slump in travel during the pandemic, leisure trips are outperforming business and international travel - namely to beach and mountain destinations.
"That is probably why United would be using these aircraft in the schedule rather than other, newer aircraft," aviation consultant Samuel Engel said.
Boeing 777 makes emergency landing in Moscow after engine sensor problem
In other Boeing 777 news, a Rossiya Airlines Boeing 777 cargo plane made an emergency landing at Moscow's Sheremetyevo Airport on Friday February 26 due to a problem with an engine control sensor, the airline said.
The plane was a 15-year-old 777-300ER, according to flight tracking website FlightRadar24, which means that it has General Electric engines.
Those are different from the Pratt & Whitney PW4000 engines under scrutiny after the incidents on Saturday February 20 that prompted the suspension of operations involving planes using those engines.
GE Aviation said that it is aware of the event.
"Safety is our first priority, and our technical support teams are working closely with the airline to quickly resolve the issue and return the aircraft to normal operations," it said in a statement.
Russian airlines operate Boeing 777-300ER planes equipped with General Electric GE90-115B engines, federal aviation agency Rosaviatsiya said, adding that it is not considering suspending operation of those aircraft.
Rossiya Airlines Flight 4520, travelling from Hong Kong to Madrid, touched down in Moscow at 0444 local time (0144 GMT) on Friday February 26, data from Flightradar24 showed.
Rossiya Airlines, which is a unit of Russian state carrier Aeroflot, said that the crew requested the landing at the airline's base airport in Moscow.
"The landing took place normally," Rossiya said in a statement.
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