By Scott Hamilton
May 27, 2026, © Leeham News: GE Aerospace says that CFM International LEAP engines being shipped now will match the durability of the venerable CFM-56.
This was a goal promised when the LEAP first went on sale, competing with the Pratt & Whitney GTF in 2010. PW also promised durability comparable to that of the International Aero Engines V2500. The CFM56 powers the Boeing 737NG exclusively and shares power with the V2500 on the Airbus A320ceo. The LEAP-1A shares power with the GTF on the A320neo. The LEAP-1B exclusively powers the 737 MAX. The GTF entered service in December 2015, followed by the LEAP-1A shortly thereafter. The LEAP-1B entered service in May 2017.
Both engines fell well short of the guaranteed on-wing time.
GE Aerospace’s testing regimen to improve durability for its major engine programs. Credit: GE Aerospace.
Poorer durability than expected for both engines means parts failed or wore out more quickly than expected. Degraded parts also increased fuel consumption. Higher maintenance costs, in some cases significantly higher, offset double-digit fuel consumption savings each engine achieved. PW’s problems exploded into an industry-wide operating crisis as upwards of 700 A320neos, scores of Airbus A220s, and a handful of Embraer E195-E2 were grounded (aircraft on ground, or AOG) awaiting engine repairs or replacements.
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CFM’s joint venture partners, GE and Safran, faced premature engine removals and a smattering of AOGs.
Dust
Among the problems facing GE’s engines on A320s, 737s and widebody aircraft is the harsh Middle East environment. Engines from Pratt & Whitney and Rolls-Royce face the same problems.
Super-heated temperatures in the Middle East are just one challenge facing engine makers. Another is dust.
There are all kinds of dust. In the Mid-East, pollutants, toxic chemicals, and bio-hazards contribute to the extreme temperatures and abundance of sand to make this one of the harshest environments in the world.
This environment gives all engines from all manufacturers a fit when it comes to durability—time on wing.
GE Aerospace didn’t historically do much in the way of testing dust for its effects on engine parts. Due to experience with the harsh Middle East environment, it now does. This is a LEAP-1A engine used on the Airbus A320neo. A RISE Open Fan engine is behind this engine. GE has now done dust testing on the GEnx (Boeing 787, 747-8) and GE9X (Boeing 777X). Credit: GE Aerospace.
GE manufactures its own dust for testing in the Evandale plant. Officials are confident that its dust testing in the LEAP and the potential RISE Open Fan engine is making significant progress toward achieving durability in the Middle East environment. (While the LEAP testing isn’t directly applicable to the widebody GEnx on the 787 and Boeing 747-8, and the GE9X that powers the forthcoming Boeing 777X family, some testing can be used on certain components of these engines.)
“When we put out the original GEnx design, we didn’t run any sort of dust testing, but we did do endurance testing in a clean environment ahead of time,” said Carlos Perez, VP Product Safety, Quality and Engines, of GE Aerospace during a media briefing this month.
“What we found is the engine worked pretty well in that environment. But particularly in the Middle East, we found, after a number of years, that the engine was only meeting about half of the time on wing that we needed for our customers. It was coming off very early. It’s very analogous to what’s happening right now.”
Reverse Bleed System
One troublesome event in the LEAP has been coking. This occurs at the fuel nozzles, where fuel solidifies after engine shutdown as the superheated air lingers. Coking may also occur on the blades, creating instability. Coking occurs because the temperature fluctuates.
Damaged fuel nozzles must be swapped, a process that can occur in the field and with engines on-wing. It’s a maintenance burden because it takes a few days. In addition to disrupting aircraft utilization, there is a cost involved. There is also a potential safety issue if fuel lingers on pipes or parts.
A Reverse Bleed System (RBS) was developed to prevent coking, premature removal of fuel nozzles, and to eliminate the safety risk.
The LEAP-1A was the first to be affected. The RBS, simplistically, sucks cool air from the outside of the engine after shutdown to lower the temperature of the engine, preventing coking. RBS was introduced about a year and a half ago. About 60% of the LEAP-1As have been retrofitted and added to new-production engines.
Production for the LEAP-1B RBS begins this year.
Durability and reliability
“Our customers want time on wing, which I would call durability,” said Carlos Perez, VP Product Safety, Quality and Engines, of GE Aerospace, during a briefing this month at GE’s Evandale (OH) facility. In the intervening time, the reliability of the product is, does it start when I say it’s going to start? Do I have to do a lot of individual maintenance?”
GE Aerospace’s engines dominate the global commercial jetliner industry. Complaints about the time-on-wing (durability) of the GEnx and LEAP-1A engines are current complaints, but these have better records than older designs. Credit: GE Aerospace.
Carlos Perez, VP Product Safety, Quality and Engines, of GE Aerospace. Credit: Leeham News.
Perez added that GE’s customers also want predictability of maintenance and when the engines are going to come off wing, and any intervention that they’re going to have to make on the engine. “They want to be able to understand it as soon as possible, right, because they want to just have stable operations where they can do their work.”
Complaints about the LEAP engine on Airbus A320neos and Boeing 737 MAXes durability being a fraction of the CFM56 on the older generation models have been loud and clear. (Airlines and lessors also complain about the LEAP’s competitor, the PW GTF, and, on widebody aircraft, the Rolls-Royce and GE engines on the Boeing 787 and the RR Trent XWB-97 durability on the Airbus A350-1000.)
Mohamed Ali, president and CEO of GE Aerospace’s Commercial and Engine Services (CES) division. Credit: Leeham News.
The LEAP engines are used exclusively on the 737 MAX and have a dominant market share on the A320neo. Mohamed Ali, president and CEO of GE’s Commercial Engine and Services division (CES), says that the LEAP-1A engines being delivered today should have the on-wing durability achieved by the CFM56. This engine entered service in 1982 on the re-engined Douglas DC-8-60 Series (rebranded the 70 Series when equipped with the CFM56). On-wing time for many years was worse than the LEAP’s early years. The CFM56 has been in service and evolved over 44 years. The LEAP-1A entered service in late 2015, almost 11 years ago.
The 787’s GEnx also has had durability issues, though not as severe as the LEAP. Still, compared with the CF6 used on the Boeing 767, early 747s, McDonnell Douglas DC-10s/MD-11s and some Airbus A330s, the GEnx has a far better on-wing time. But it’s not good enough. Ali says the next durability target for the GEnx should be met in 2028.
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