Dry Motoring Duty Cycle Limits #1 specify an ON time of?

Dry Motoring Duty Cycle Limits #1 specify an ON time of?

• A. 90 sec ON / 5 min OFF
• B. 30 sec ON / 5 min OFF
• C. 15 min ON / 5 min OFF
• D. 60 sec ON / 5 min OFF

Answer: (A)

Dry motoring limits set how long you can spin the engine without fuel to check systems while controlling heat buildup. For the first dry motoring limit, you may run the engine for 90 seconds, then require a 5-minute cooling interval before the next cycle. That 90-second ON window gives enough time to observe oil pressure, starter/system indications, and rotating clearances, while the 5-minute OFF period prevents excessive heat buildup in the turbine and bearing areas since there’s no combustion adding heat. The other options would either be too short to perform meaningful checks or too long, risking overheating without combustion.

Dry motoring limits set how long you can spin the engine without fuel to check systems while controlling heat buildup. For the first dry motoring limit, you may run the engine for 90 seconds, then require a 5-minute cooling interval before the next cycle. That 90-second ON window gives enough time to observe oil pressure, starter/system indications, and rotating clearances, while the 5-minute OFF period prevents excessive heat buildup in the turbine and bearing areas since there’s no combustion adding heat. The other options would either be too short to perform meaningful checks or too long, risking overheating without combustion.