Like all machinery, aircraft need spare parts for when their components fail and break down. A major part of stocking spare parts revolves around dealing with unexpected breakdowns. The mean time between unscheduled removals (MTBUR) is the average interval between breakdowns, but in smaller fleets of aircraft that have a smaller sample size, the actual interval can vary wildly. Therefore, airlines typically follow schedules that plan for the “sooner” half of “sooner or later.” Even then, the variance in breakdown intervals can mean that owning a large stock of spare parts is too expensive to be feasible.
Therefore, airlines will often share access to parts pools, splitting the risk with each other. Even larger airlines will do this at outstations with few flights, in case they have an aircraft on ground (AOG) situation that needs immediate attention. Accessing a parts pool with its own maintenance team can save money as well. However, pooling parts means reduced control over assets, which for carriers concerned with part quality, configuration, and documentation. Dedicated parts
pools serving one airline fulfill these needs for control, but the tradeoff is less efficiency that wider pools provide.
One example of parts pooling is Luxembourg-based International Airlines Technical Pool
(IATP). For over seventy years, IATP has let 104 airlines share parts, equipment, line maintenance, and aircraft recovery kits at over four hundred different airports. At each airport, IATP assigns a value, and each member there pays an equal share of 20% of this value per year. In return, members can borrow needed parts for fourteen days, with a seven-day grace period to return it. IATP also offers the skills and services to install needed parts, an attractive offer for carriers that might not be able to afford teams of their own in every airport they operate out of. While most airliners carry minimum stocks of the most essential and frequently used components
, the economics favors using pools at outstations.
Another example of parts pooling is Spairliners, which manages pools, repairs, and support for Airbus A380s and Embraer E-Jets. A joint venture between Lufthansa Technik and Air France Industries based out of Hamburg, Spairliners’ pools support flight-hour programs, including line-replaceable units (LRU) common to many operators, but excluding carrier-specific consumables and cabin equipment. Head of sales and marketing Fabrice Dumas, claims that pool-supported programs have become more popular for several reasons: modern-day repairs require more investment in equipment, finances encourage tighter cost control, airlines are reluctant to invest cash in stocking parts, and pool-supported flight-hour maintenance turns fixed costs into charges that vary with schedule, thus lowering overall expenditures.