The commercial aviation aftermarket is facing an unusual supply problem: aircraft that were expected to leave the fleet are remaining in service, limiting the flow of used serviceable material (USM) just as airlines and MRO providers are relying more heavily on the aftermarket to keep ageing fleets operational.
Avation’s September 2026 investor presentation highlights the underlying fleet dynamic. Manufacturing delays have pushed the average global aircraft age to 14.8 years, compared with an average of 13.6 years between 1990 and 2024. The lessor said supply constraints are encouraging airlines to extend the operating lives of existing aircraft, increasing the useful life of mid-life assets.
For MRO providers, however, keeping aircraft in service for longer has a second-order effect: fewer aircraft are available for teardown.
That is becoming increasingly important for USM. IATA’s 2026 analysis of the commercial aircraft supply chain notes that the availability of USM is being constrained because many older aircraft that were expected to retire are still flying. At the same time, parts shortages are increasing demand for USM and other approved alternative solutions.
The result is a difficult equation for the aftermarket. More ageing aircraft require maintenance, but fewer retired aircraft are available to supply the replacement parts needed to perform that maintenance.
Retirement slowdown changes the parts equation
Aircraft retirement is an important source of material for the aftermarket. Once an aircraft is withdrawn from service, engines, landing gear, avionics, flight-control components and other rotable and repairable parts can be removed, inspected, repaired and returned to the market.
A slower retirement cycle reduces that supply.
IATA’s June 2026 Global Outlook estimates that delayed retirements account for the equivalent of around 1,700 aircraft in the industry’s current effective capacity shortage. The association also warns that continued reliance on older aircraft is increasing exposure to maintenance disruptions.
This means the retirement market is no longer simply a question of aircraft values and teardown economics. For MRO providers, lessors and parts suppliers, the timing of retirements is increasingly connected to the availability of material for aircraft that remain in operation.
MRO turnaround times add another constraint
The shortage is occurring alongside longer repair and overhaul turnaround times.
IATA’s supply-chain analysis, drawing on Oliver Wyman’s 2025 MRO industry survey, found that 80% of respondents identified piece-part availability as the leading cause of increased turnaround times. Some engine shop visits are now taking more than 300 days, while landing-gear overhauls that historically took about 45 days can take 90 to 120 days under current conditions.
Longer turnaround times create another inventory problem. More components remain inside the repair cycle instead of being available on the shelf, forcing airlines and MRO providers either to carry additional inventory or accept lower material availability.
For older fleets, that pressure can be particularly acute because operators may have fewer alternative sources for legacy components.
Engine MRO faces a parallel capacity challenge
The same supply constraints are affecting newer-generation engines, although for a different reason.
IATA’s June 2026 engine MRO study identified spare-parts shortages, limited spare-engine availability, engine durability issues and constrained aftermarket access as factors disrupting airline operations. The organisation said airlines affected by GTF engine issues have had to retain older aircraft, extend leases or obtain additional aircraft to maintain capacity.
At the same time, the number of engine shop visits is expected to increase substantially as newer fleets mature. IATA forecasts annual LEAP shop visits to rise from around 600-800 in 2025 to more than 5,000 by 2040, while GTF shop visits are expected to increase from around 1,000 to more than 2,000 over the same period.
This creates two overlapping aftermarket pressures: ageing aircraft are staying in service longer, while newer-generation engines are moving toward their own increasingly demanding maintenance cycles.
USM becomes more strategic
The combination makes USM increasingly important to MRO planning.
For airlines, serviceable used components can provide an alternative when new parts are unavailable or when the economics of installing new material do not make sense for an ageing aircraft. For MRO providers, access to teardown material can help reduce dependence on constrained new-part supply and support aircraft return-to-service timelines.
But the current retirement slowdown means the aftermarket cannot assume that a steady stream of aircraft will become available for teardown.
IATA has consequently identified greater access to USM recovered from engine teardowns as one of the measures that could improve engine MRO resilience. It has also called for expanded repair solutions and greater access to approved alternative parts.
Capacity planning becomes more important
The changing retirement cycle is therefore influencing more than parts availability. It is affecting how MRO providers plan capacity.
Heavy airframe checks, component repair, engine shop visits and landing-gear overhauls all compete for technicians, tooling, materials and shop capacity. If aircraft remain operational beyond their originally expected retirement dates, those requirements can move further into the future and become more difficult to forecast.
For lessors, meanwhile, maintaining older aircraft in service can extend asset lives and create opportunities to keep mid-life aircraft leased. Avation’s presentation specifically links supply constraints and fleet ageing with longer operating lives for existing assets.
For MRO providers, the implication is different: the aircraft may stay in the fleet, but the aftermarket infrastructure supporting those aircraft has to stay ahead of their maintenance requirements.
The current environment is consequently shifting the importance of teardown and USM from a traditional end-of-life activity toward a strategic part of fleet support.
Until new-aircraft production and deliveries allow retirement rates to normalise, MRO providers will have to manage a market in which more aircraft need maintenance while fewer retired aircraft are supplying the aftermarket with recoverable material.
That makes USM availability, repair capability, inventory positioning, and MRO capacity increasingly interconnected parts of the same aircraft lifecycle equation.
