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Groundings of Spirit Airlines’ Airbus A320neos could triple in 2025.
Pratt & Whitney’s plan for inspecting thousands of critical PW1000G engine parts with contaminated powder metal is progressing largely as the manufacturer projected when it kicked off a year ago, although that astute forecasting offers little consolation for operators grappling with grounded aircraft.
The plan, unveiled in the middle of summer last year, called for engine removals starting last September for inspections of specific life-limited parts (LLP) for cracks in forged parts containing powder metal (PM). Many of the inspections were accelerated compared with Pratt’s projected overhaul intervals for the PW1000G engines.
The surge of premature shop visits hit an overhaul network already at capacity from swapping parts out to correct a series of unrelated durability issues. The combination led Pratt to lay out some dire projections.
Chief among them: Wing-to-wing turnaround times (TAT) would run about 300 days, thanks to a combination of long waits to put engines into shops and heavy workscopes.
The PM inspections require a special angle scanner but are not particularly complicated or time-consuming. Pulling an engine off wing to inspect one part is a poor use of resources, how-ever, so Pratt and PW1000G risk-sharing partner MTU Aero Engines developed tailored workscopes to help ensure that engines going back out can stay on wing as long as possible.
But a lack of available full-life parts means not all contaminated parts are being swapped. A parts crunch is also contributing to long shop visit times, forcing Pratt to balance longer TATs with workscopes that benefit operators in the long term.
MTU is putting considerable effort into optimizing workscopes to minimize time engines spend on the shop floor. Among its focus areas is making sure parts are available before work begins. Those efforts are bearing fruit: Some PW1000Gs have come and gone from MTU’s shops in under 100 days, CEO Lars Wagner said on an Aug. 1 earnings call. Pratt’s 300-day estimate includes about 150 days of in-shop time.
Meanwhile, Pratt is ramping up spare parts production. The PM problem was corrected at the component level in late 2021, but supply-chain dynamics meant Pratt was still delivering new-build engines with contaminated parts to Airbus as recently as late 2023. The alternative—disposing of the remaining suspect inventory—would have forced Airbus to pause deliveries of Pratt-powered aircraft.
Instead, Pratt kept producing engines and directed new, full-life parts to its PW1000G production line as quickly as possible. Once all new engines, including designated spares, were being shipped with full-life parts, attention turned to the MRO shops.
“MRO was always a phased ramp-up,” Christopher Calio, president of Pratt parent RTX, said on a late July earnings call. “We’ll start to see this ramp up here in the second half of the year, and it’s going to continue to accelerate into 2025 and into 2026.”
Fewer than 1% of affected parts have failed shop inspections so far. While this helps keep engines moving through the MRO process, the powerplants still must return for repetitive checks based on reduced life limits. The most restrictive reductions, applying to Airbus A320neos with the highest-thrust variant PW1100Gs, mean engines must come back within 2,800 cycles—less than one year of activity for the busiest A320neos in the global fleet.
The combination of unscheduled overhauls, already crowded shops and a shortage of spares to serve not just the PM issue but also the unexpected run of shop visits drives Pratt’s most critical projection: total aircraft on ground (AOG).
Pratt’s calculations saw a sharp rise in PW1000G-powered AOG in late 2023 and into 2024, peaking at around 650 by midyear. As engines begin to return from their overhauls and TATs increase, the figure is expected to fall to about 350 aircraft and stay there through 2026.
The projections are proving accurate—and in some cases, conservative. The AOG peak occurred in May and slightly below Pratt’s expectations.
But the long TATs—a 300-day turn means engines removed in January will not be flying again until around Nov. 1—are keeping AOG relatively high. Aviation Week Network Fleet Discovery data showed total PW-1000G-powered aircraft groundings at about 630 aircraft on Aug. 20. The figure includes aircraft out of service for any reason, not just the PM inspections. But most are sidelined awaiting engines going through the PM fleet management plan.
The plan targets LLPs made between Nov. 1, 2015, and Sept. 1, 2021. Parts affected are high-pressure turbine Stage 1 and 2 disks as well as high-pressure compressor (HPC) seventh and eighth integrally bladed rotors, and aft disks. Most of them are installed on PW1000G variants, but some are on other engine types that power business jets and even Lockheed Martin F-35s. The commercial fleet’s activity levels make it most subject to the problem’s ramifications—premature cracking made worse by usage.
Within the PW1000G fleet, the PW1100G-powered A320neo variants have been the hardest hit due to the number of affected aircraft, high utilization rates and longer time in service. But A220 operators are not much better off.
All-A220 operator AirBaltic expects to be without as many as 36 PW1500G engines during its upcoming winter season. The carrier has 48 A220s and 20 more on order, meaning the inspections could put about a third of its fleet on the ground.
“Parts are not available, and slots in the shops are not available,” CEO Martin Gauss said at the recent Aviation Week Network MRO BEER conference.
The FAA issued a draft of its latest mandate for the A220’s PW1500Gs and Embraer E2’s PW1900Gs on Aug. 19. This set of inspections—like the others, based on FAA-vetted, Pratt-issued service bulletins—targets HPC seventh-stage axial rotors. The initial inspection threshold is 10,000 cycles, far above where most of the affected fleet stands. Only about 10 of the 335 A220s in service have hit the threshold, and none of the E2s have.
Pratt issued the related service bulletins in May and August; the directive is not expected to be finalized until late this year at the soonest.
As both initial and repetitive inspections mount, Pratt is bolstering resources. Increasing spare parts production is the most direct response. The company also is accelerating its planned expansion of PW1000 MRO capacity (see article below).
While expanded parts production and shop capacity are alleviating the fleetwide ramifications, some airlines’ situations will worsen. Spirit Airlines expects its full-year 2024 average of 20 Pratt-powered AOG to triple in 2025.
“There’s simply not enough spares in the system, and there’s not enough throughput yet on the MRO side,” Spirit CEO Ted Christie said on an earnings call. He also cited TATs “north of 400 days” as a contributor.
RTX’s Calio and MTU’s Wagner said TATs on the heavy-shop visits completed thus far have been closer to 300 days, and a senior executive with a European operator described turn times as better than expected.
The lingering uncertainty helped convince JetBlue Airways, citing both the PM issue and unrelated durability issues as major headwinds, to defer delivery of 44 PW1100G-powered A321neos on order until after 2030. The carrier plans to invest in older-generation A320s to help offset the loss of the A321neo seats.
