Engine maintenance accounts for 52 per cent of about $120 billion of global aerospace maintenance spend, on figures from IATA and Oliver Wyman for 2025. That is roughly $62 billion passing through engine shops in a single year, and the queue to get into one is now the constraint on how many aircraft fly.

The framing has changed. Through 2024 and most of 2025 the engine story was the Pratt & Whitney geared turbofan inspection campaign and the aircraft it put on the ground. That campaign is easing. What has replaced it is a capacity and price story, and the five companies at the centre of it are experiencing it in very different ways.

Pratt & Whitney is paying for the recovery out of the recovery

Pratt’s own peak framing was about 650 geared turbofan powered A320neo family aircraft on the ground. RTX reported that PW1100G groundings fell about 15 per cent in the first quarter of 2026 against the end of 2025, and about 25 per cent across the first half. Second quarter repair output on the engine was up 43 per cent year on year with turnaround times down 23 per cent.

A note on counting, because the numbers in circulation are not the same number. Cirium recorded 720 stored PW1100G powered A320neos out of 1,912 at the end of October 2025, and 835 stored across all geared turbofan variants. Those are storage snapshots from ten months ago, not a current census of aircraft on the ground, and they are widely quoted as though they were current. They are not. Pratt does not publish a current integer.

The bottleneck has moved. It was the inspection of a specific disk. It is now shop capacity, castings and forgings, and workscope mix: second quarter heavy repair content on the PW1100G ran 14 percentage points higher than a year earlier. Pratt announced more than $100 million of additional United States maintenance investment in the second quarter across Texas, Florida and Arkansas.

The bill continues. Customer compensation for the powder metal issue was about $150 million in the second quarter against a three year cumulative of $6 to $7 billion. That is a residual rather than a new wave, but full fleet recovery is still described by management as an end of decade event. The GTF Advantage received European certification for the A320neo and A321neo in April 2026 with first shipsets delivered in May, and full production cutover is 2028. Hot Section Plus, a set of about 35 Advantage parts that Pratt says delivers 90 to 95 per cent of the Advantage durability improvement, is expected to certify in late 2026 or the first quarter of 2027.

The aftermarket is funding the recovery. Pratt’s second quarter sales were $8.89 billion, up 16 per cent, with commercial aftermarket up 25 per cent and adjusted operating profit of $740 million.

Rolls-Royce turned the same constraint into margin

Rolls-Royce ran 556 large engine shop visits in the first half of 2026 against full year guidance of 1,480 to 1,550. Large engine maintenance output rose 13 per cent and refurbishments, the lighter and faster category, rose 35 per cent. Civil aerospace sales were £6.2 billion, of which 67 per cent were services. Group operating profit was £2.5 billion against £1.7 billion, with £574 million of gross contractual margin improvement across widebody and business aviation maintenance in the half.

The installed base explains the durability of that position: 4,674 Trent engines in service with a further 2,266 on order, and more than 90 per cent of Trent engines sitting on long term service agreements. Access to that work runs through an authorised network rather than an open market.

There is a catch inside the good news. Rolls says time on wing across Trent programmes has roughly doubled against a 2023 baseline. An engine that stays on the wing longer visits the shop less often, and the company’s own guidance has large engine shop visits falling to between 1,300 and 1,400 by 2028 even as the installed base grows. Durability improvement and shop volume pull in opposite directions.

Safran is running two cash clocks at once

Safran’s first half showed civil spare parts up 27.9 per cent in dollars and civil services up 40.4 per cent, with propulsion recurring operating income of €2,253 million at a 24.5 per cent margin. LEAP deliveries reached 1,030 in the half, up 41 per cent, and the full year outlook was raised.

The two engines are doing different work. Spare parts growth is led by CFM56 workscope mix: the retiring generation is still the parts engine, and delivery slippage on the A320neo and 737 MAX keeps earlier generation aircraft flying and consuming. Services growth is led by LEAP rate per flight hour contracts on the new generation. GE’s chief executive said in July that LEAP related aircraft groundings had fallen to near zero.

That does not mean the new generation is cheap. Oliver Wyman’s April 2026 maintenance survey found two thirds of respondents reporting that next generation narrowbody shop costs exceed expectations by 21 per cent or more, with a quarter saying 50 per cent or more, and narrowbody engine turnaround times regularly running 180 to 200 days or more.

Honeywell and Melrose are the two ways to own the same hours indirectly

Honeywell Aerospace completed its separation on 29 June 2026 and trades as HONA, with more than $17 billion of 2025 revenue and leading positions in propulsion, cockpit systems and auxiliary power. It remains the dominant commercial auxiliary power unit manufacturer. The first standalone quarterly report is the next real data point, and there is no reliable 2026 market size figure for auxiliary power maintenance in the public record.

Melrose is the clearest listed window on tier two engine economics. Its engines division reported first half revenue of £896 million, up 19 per cent, with adjusted operating profit of £303 million at a 33.8 per cent margin. Civil risk and revenue sharing partnerships grew 18 per cent, and legacy narrowbody aftermarket on the V2500 and CFM56 grew 27 per cent. Repairs grew 27 per cent despite continuing powder shortages.

One number requires care. Of the £303 million of adjusted operating profit, £206 million is variable consideration, which is the accounting recognition of expected future aftermarket income on those partnerships rather than cash received in the period. The cash bridge reverses it. Both figures belong in any assessment.

What this means

For airlines, the constraint is not money. It is a slot. Short term leases on spare LEAP and PW1100G engines now clear above $6,500 a day against roughly $5,000 in 2022 and 2023, which is what scarcity looks like when it reaches the rental market.

For lessors, the arithmetic has moved to the engine. Around 65 PW1100G powered A320neos are already parted out or committed to teardown, releasing roughly 130 engines, because the engines are worth more off the wing than the aircraft is worth flying.

For investors, the question is not which manufacturer has a problem. It is who owns the queue. Pratt is still paying for durability while building throughput. Rolls-Royce and Safran are collecting on installed bases that cannot go anywhere else. Melrose takes a share of the same hours without carrying the original equipment risk.

The labour constraint sits underneath all of it and does not resolve on any of these timelines. McKinsey estimates a shortfall of about 22,000 full time equivalent technicians by the end of 2026, rising toward 60,000 by 2029. Engine shops need the most specialised skills in maintenance and pay a premium to get them. Bain’s July 2024 forecast, which remains the unrevised public projection, has shop visit demand peaking in 2026 and cumulative demand through 2030 exceeding supply by nearly 17 per cent on the capacity growth then anticipated.

Boston Warwick’s MRO advisory practice works on capacity planning, shop selection and maintenance cost modelling for airlines, lessors and investors. The fuel cost dimension that sits alongside these maintenance economics is set out in The $159 Barrel, which is free, and in the two reports that follow it on 8 and 15 September at $100 each or $150 for both.