Recently an engine manufacturer published a bulletin which defined severe damage assessment in terms of QRH actions. It may have been part of an Airbus document published by the flight safety department of a major airline but I am unsure.
Broadly, the document defined severe damage if significant vibration is noticed during the engine operation/failure. In the case of the Boeing 737 for example, the QRH drill is to shut down the engine and pull the fire fire switch. It is not necessary to fire a bottle unless there are indications of engine fire. One of the engine instrument indications or a turbine seizure (Severe Damage) is the N2 indicating zero.
The flight safety bulletin quotes the manufacturer that the cue for using the Severe Damage checklist is if significant engine vibration is present.
One of the engine non-normals available in some simulators is Accessory Gear Box Shaft Failure. In effect this causes a flame-out due lack of fuel to the burners. There is no vibration present (simulator) although the N2 indicates zero the same indication also being seen with a turbine seizure.
Opinons are sought as to whether an Auxilliary Drive Shaft failure is by defintiion, a Severe Damage Checklist QRH action or not. The B737 FCOM, QRH or FCTM do not amplify this particular event and it is left to the crew to decide the appropriate QRH drill. This gives rise to personal opinions and we all know about personal opinions in a simulator.
Clearly, if significant vibration does not exist then presumably severe damage is not present even though the engine has flamed out because of the auxilliary drive shaft failure. Opinions welcomed of course but preferably back up with published data. Thanks in advance
