On 1 October 2026 the European Union Aviation Safety Agency issued an airworthiness directive covering every serial number of the four certified variants of the Rolls-Royce Trent 700, the engine that powers Europe’s Airbus A330 tankers. Seven days after it takes effect, an aircraft may no longer fly with an affected oil pump on both of its engines: if one engine carries such a pump, the other must have a serviceable one. The directive is a safety measure, and nothing in it indicates that any European military tanker is affected. It nonetheless exposes something that fleet counts conceal. Whether a tanker can fly depends not only on how many aircraft a state or an alliance has bought, but on whether, when an engine has to come off the wing, a compatible and serviceable replacement can be obtained, installed and released to service within a predictable time. Europe operates its A330 tankers under three very different arrangements: a fleet owned by NATO and shared among European allies, a British fleet provided under a private finance contract, and a French fleet ordered by the state and operated by its Air and Space Force. The common engine invites a comparison of aircraft numbers, but readiness rests on a less visible question. When an installed Trent 700 must be removed, what access to a serviceable replacement does each operator actually hold, through ownership, an exchange or pool entitlement, reserved maintenance capacity or a broader availability commitment, and how much of that access can an outside reader see?