Pratt & Whitney will soon begin modifying a Lufthansa-operated PW1100G geared turbofan with changes aimed at reducing engine start delays.
The Lufthansa engine will be the first in-service PW1100G to undergo the modification, and the work will mark the start of a project that will see P&W modify dozens of engines over the next several years, P&W aftermarket president Matthew Bromberg tells Flightglobal.
“Pretty soon we will be taking a Lufthansa motor in. That will be the first engine that actually saw flight time,” Bromberg says, though he does not provide a more-specific timeline.
The modifications will address an engine-start delay issue that affects roughly the first 40 PW1100Gs delivered to airlines.
Under certain circumstances, those engines must cool for 3min prior to being started, a period that is longer than the industry-standard of 1min, airline chief executives have said.
The delay is needed because rising heat after shutdown can cause a bowing of the engine’s rotor, and, if the engine is started too soon, that bowing can cause vibration and possible engine damage, P&W has said.
Specifically, Bromberg says the bowing of the rotor can cause the rotor tips to “eat into” the surrounding seal in an uneven fashion.
“In the prior configuration the motor is bouncing and taking chunks out of the seal, which erodes the efficiency,” he says.
The fix involves applying a coating to the rotor tips, he says.
“It’s a special coating which will eat into the seal in a smooth fashion, which will prevent the cutting,” says Bromberg.
“It’s not a geometric part change to the rotor,” he clarifies. “It’s a seal on the tips of the rotor.”
P&W has said the modification will cut the start delay in half.
The work will be done at P&W’s site in Columbus, Georgia, where a team has already started modifying a spare engine that the manufacturer had on hand.
Bromberg expects work on that engine will take 60 days to complete, but predicts his team will reduce that time to 45 days, including 15 days for engine disassembly and 15 days for reassembly.
“This is right in the core of the motor,” Bromberg says of the fix. “You have to… get to the two bearings and the compressor rotor that has to be changed out with the new hardware.”
P&W says new engines coming off the production line already have the fix, but it must retrofit the first roughly 40 engines in service.
“It will take a couple of years,” says Bromberg. The engine start issue irked several airline CEOs, the most vocal being Qatar Airways chief Akbar Al Baker.
Though Qatar was an Airbus A320neo launch customer, Al Baker deferred that designation to Lufthansa, citing the engine start delay.
Source: Cirium Dashboard