Emergencies

Question 1

Engine over speed

Answer 1

If N1 can be controlled with throttle then N2 governor failure or N2 accessory drive train failure has occurred.

If N1 and N2 is unstable then FCU failed or N1 accessory drive train failure and if N1 accessory failure it will be indicated by rapid engine oil pressure loss.

Indications:
Increase in RPM-rotor/N1/N2 and torque
Procedure:
Retard Throttle 
N1/N2 control with throttle
Monitor TOT
Adjust collective to maintain 90-107%
Adjust cyclic for desired airspeed 
Prepare for autorotation 
If TOT and RPM cannot be maintained shut engine off

Question 2

Engine under speed

Answer 2

Indications:
Abrupt decrease in N1 rpm
Then decrease in N2 rpm
Possible Nr decrease and torque

Procedure:
Lower collective maintain 90-107 rpm
Throttle idle stop
Maintain autorotation glide
Prepare for power off landing

Question 3

Compressor stalls

Answer 3

Indications:
Engine pops
Erratic N1/N2 
High and erratic TOT
Erratic Torque 

Procedure:
Lower collective
TOT and N1 check for normal operations
Anti ice on

Severe pops cause damage to drive train system and engine shut down with autorotation required