exceeding engine limitations

[PPRuNeUser0179]

Hi guys
I did not know if I should post this in the Engineers and Technicians Forum or in the Questions Forum so please excuse me if I made an error.
I'm curious as to what happens when you exceed you main engine gauges in a turbine helicopter?Possibly a Bell 206 Jetranger.
I'm referring to the N1,TOT,TRQ,Nr,N2.
I know that you will exceed your torque way before you exceed your N1 and TOT (in the 206) but I am just curious as to what events will lead up after exceeding each of these gauges:
1)N1
2)TOT
3)TRQ
4)Nr
5)N2

This may be a silly question but there is no such thing as TOO much knowledge right?
Thanks guys :ok:

[NZScion]

It depends by how much and for how long...

I can't comment on a Bell 206 (or any other helicopter), but some turbine engines have transient limits that can be exceeded under specified circumstances. Your best bet would be to look in the flight manual/fcom or wherever else limitations such as this would be found for your aircraft.

[PPRuNeUser0179]

thanks for the reply.
I have read that you can exceed your TOT and Torque for only +-5 seconds in an emergency but wanted to know what would happen if you continue to exceed after the specific time.
But thanks again.Ill look in the 206 manuel.

[AerocatS2A]

Exceed the TOT or similar value (ITT, TGT, EGT etc) and you will shorten the life of the turbine section. How much it is shortened by will depend on how hot it got and for how long. A series of minor exceedances may result in an earlier than usual engine change while a major exceedance may result in a failure on the current flight.

[parabellum]

I know that you will exceed your torque way before you exceed your N1 and TOT (in the 206)


Are you sure about this? I ask because way, way back I flew the 206A in the tropics, ambient temp. 30+ most of the day and you would exceed EGT before Torque under those circumstances, possibly engine improvements have changed this now?