What must be monitored while motoring a cold soaked engine?

Monitoring N1 fan speed while motoring a cold soaked engine is crucial because it helps ensure that the engine is functioning properly and safely. When the engine is cold soaked, it means that it has not been run for a while and all the fluids, particularly oil, have cooled down significantly. During motoring — a process where the engine is spun without fuel being injected to check for mechanical integrity — the N1 fan speed provides immediate feedback on the performance of the engine's components.

By observing the N1 fan speed, operators can detect any abnormalities that may indicate issues such as abnormal friction or mechanical failure. An unexpectedly low or erratic N1 reading could highlight potential mechanical problems that need to be addressed before proceeding. Thus, it's essential to monitor this parameter as part of the engine's health check process.

While oil temperature, fuel flow, and N2 fan speed are also relevant parameters in engine monitoring, N1 is specifically critical during the motoring phase for ensuring the engine's integrity and readiness for operation.