The engine starter should be limited to what maximum speed?

The maximum speed limit for an engine starter is generally set to ensure the safe operation and longevity of both the starter and the engine components it engages. In turbojet and turbofan engines, the typical maximum starter speed is around 80,000 revolutions per minute (rpm). This speed allows the starter to efficiently crank the engine and facilitate the ignition process without causing undue stress on the starter motor or the engine components.

Operating above this threshold, such as 90,000 rpm, could lead to excessive wear or potential failure of the starter, while speeds at 60,000 or 70,000 rpm might not provide sufficient power for effective engine start-up under all conditions. Therefore, 80,000 rpm is established as an optimal limit balancing performance and safety.