Message Name:

N1 SPEED IS TOO HIGH IN REVERSE THRUST

The speed of the N1 Rotor is more than the permitted limits. During Engine operation the N1 Rotor speed is continuously monitored by the Full-Authority Digital Engine Controller (FADEC).

• Power Plant

Advisory Wire/Service Bulletin: None

Forum Articles/Infoservice/Newsletter: None

1. Perform the fault isolation for the N1 overspeed condition in reverse thrust. On the EICAS display system get access to the engine exceedance profile maintenance pages. Record the exceedance profile for N1 rotor speed as follows:

   • The maximum speed of the N1 rotor
   • The quantity of time that the N1 speed was more than the limit
   • If the N1 overspeed was stable or not

2. Use the exceedance profile data above and the N1 overspeed limits in reverse thrust graph (Figure 1) to find out if the N1 overspeed was in Zone A or Zone B.

   1. If the N1 overspeed is in Zone B, go to step 5.
   2. If the N1 overspeed is in Zone A, continue with next step.

3. Perform the fault isolation procedure for N1 speed is too high in forward thrust.

   1. If the system checks are good, do close out.
   2. If fault remains, continue with next step.

4. Perform a general visual inspection of the thrust reverser for damage and an overheat condition.

   1. If the above checks and inspections are satisfactory, put the engine back to usual operation and do close out.
   2. If the above checks and inspections are not satisfactory, refer to your Rolls-Royce representative and do close out.

5. Replace the power plant.
6. Do close out.