On the MAX, what does the MOTORING indication on the N2 gauge mean?

On the MAX, what does the MOTORING indication on the N2 gauge mean?

• A. the Bowed Rotor Motoring (BRM) function is activated
• B. N2 gauge reads normal
• C. Engine is starting
• D. Fuel flow is abnormal

Answer: (A)

The key idea here is that the engine core is being spun without fuel to protect the rotor and bearings. When you see MOTORING on the N2 gauge on the MAX, it means the Bowed Rotor Motoring (BRM) function is active. BRM uses the starter system to rotate the core rotor while fuel is inhibited, typically to prevent rotor bowing during certain conditions (like cold soak or during an engine shutdown/restart sequence). Because the core is being turned by the starter rather than being ignited, you won’t see normal combusting engine operation or fuel flow, and the N2 gauge won’t indicate a normal spool up. So the MOTORING indication identifies that the BRM process is in effect, not that the engine is normal-running, starting with combustion, or experiencing fuel-flow faults.

The key idea here is that the engine core is being spun without fuel to protect the rotor and bearings. When you see MOTORING on the N2 gauge on the MAX, it means the Bowed Rotor Motoring (BRM) function is active. BRM uses the starter system to rotate the core rotor while fuel is inhibited, typically to prevent rotor bowing during certain conditions (like cold soak or during an engine shutdown/restart sequence). Because the core is being turned by the starter rather than being ignited, you won’t see normal combusting engine operation or fuel flow, and the N2 gauge won’t indicate a normal spool up.

So the MOTORING indication identifies that the BRM process is in effect, not that the engine is normal-running, starting with combustion, or experiencing fuel-flow faults.