Engine Vibraton

[paulhn]

Good evening
I've just been reading various forums regarding the TCX 757(?) that diverted to Gatwick due to engine vibration. The BBC report suggested that the decision was taken to land at LGW as TCX have a maintenance base there, although the aircraft could have quite safely carried on the Birmingham.

My question is how serious a problem is an engine vibration and what are the causes/implications.
Many Thanks
Paul

[JW411]

Most modern aircraft are fitted with vibration indicators. The question that has to be asked is "is the engine really vibrating" or "is the engine fine but the guages are showing excessive vibration".

If the engine really is vibrating (and that should be fairly obvious) then it could be an early warning of a bearing failure which could obviously lead to a shut-down. The usual answer is to reduce power on the suspect engine to flight idle and, if the vibration ceases, keep it running for engines don't just generate power they also power generators and hydraulic pumps etc.

If the engine is not vibrating but the guages say that it is then the guages are most likely to be at fault and the procedure would be to monitor all the other engine indications such as oil pressure/temp etc. and keep the engine running normally.

On one type of aircraft that I flew in the past, the vibration indicators were so unreliable that a lot of operators had them disconnected.

Now it could well be the case that if you had a high vibration indication on a particular engine and you happened to be passing a maintenance base then it might be a good company option to divert and land rather than risk having a bearing failure a bit later down the line from a purely commercial point of view.

Having to replace an engine could cost the company $10 million in the case of a large turbine engine.