What is the maximum ON time for dry motoring on the ground?

The maximum ON time for dry motoring on the ground is set at 90 seconds. This limitation is important for ensuring the longevity and safety of the aircraft's engines. During dry motoring, the engines are turned without fuel but can cause overheating if run for excessive periods. Therefore, adhering to this 90-second time frame helps prevent damage to engine components due to excessive heat build-up and allows for adequate cooling between attempts, which is critical for maintaining engine integrity and performance. Following these specified limits helps ensure that the engines stay within operational parameters during ground procedures.