Max Motoring

“Cold motoring” refers to the state where the aircraft engine operates without ignition or starting, powered solely by the electric motor. “Max motoring speed” refers to the maximum speed allowed for the engine in this state.

For specific applications, please refer to the description of the Boeing 737 engine start procedure on b737.org.uk.

Min 25% N2 (or 20% N2 at max motoring) to introduce fuel; any sooner could result in a hot start. Max motoring is when N2 does not increase by more than 1% in 5 seconds.

Therefore, the maximum cold motoring speed during engine start specifically refers to the condition where the N2 rise rate does not exceed 1% every 5 seconds.