Cadet pilot 206 Jetranger

[heliPilotCadet]

hi i am a cadet pilot and i am flying with ab206 jet ranger 3 . and my flight instructor asked me too find why do we wait for a while when the engine is running an idle. i looked for every documents but i couldnt glad my instructor i need that information in details. (engine oiling system) i would be very happy if anyone can help me .

thanks.

[Aspiring Pilot Alex]

I was under the impression that this heats the oil up making it less viscous so it can travel around the engine better. Thick oil aint very good at lubricating engine parts.

[heliPilotCadet]

thank u but i said that to my instructor my he want more details. he told me i should find whats happinig in n1 and n2 turbins when the engine is running idle?

[hueyracer]

What do you mean when you say "we wait for a while"?
One to 5 seconds, or 1 to 5 minutes?

The helicopter flight manual should tell you everything you need-unfortunately, some instructors like to confuse their students with information they got from a) other helicopters, b) the maintenance manuals or c) the helicopter test flight programs (normally to be found in b.)....

[Gemini Twin]

With respect to the oil system before take off you wait until both temp. and press. are in the green. No set time, depends temp at the start. Now if you are talking about staying at idle for 2 minutes before shutting down you are using the oil flow to cool the turbine bearings as much as possible to prevent carbon forming that could eventually build up to a sufficient level to reduce proper oil flow.

[gulliBell]

It's a very long time since I flew a B206 so don't speak with any authority here. If I recall the at idle wait time after start which you refer to is from a cold start, meaning the engine has been shut down for more than 15 (or is it 20?) minutes. If the engine has been shut down for less than 15/20mins you can go to full noise after start without having to wait at idle for any period.
The cool down time before shut-down also has to do with stabilizing the temperature of the turbine discs/blades. The blade tips cool down (and heat up) faster than the blade roots/disc, and allowing the temps to stabilize for a minute before shut-down minimizes the shock to the metal brought about by the rush of cold air into the engine on shut-down.
The cool down times vary of course depending on the engine, for PT6 I use 1 minute, Arriel 1S1/2S1 is 30 seconds, or whatever....

[handbag]

From POH...

IF THE ENGINE HAS BEEN SHUT
DOWN FOR MORE THAN 15
MINUTES, STABILIZE AT IDLE
SPEED FOR ONE MINUTE
BEFORE INCREASING POWER.

[heliPilotCadet]

thanks for answers. i am talkin about both waiting on start and stoping engine. 2 minutes in stoping and 1 minute before n1 %70 before we turn on the gen key.
in starting with the increase of temp press. goes down and some part of n1 and n2 turbines that r hasnt been oiled begins to be. so what happens if dont we wait at idle?

[OvertHawk]

I thought that the 1 min after start before turning on the GEN was to allow the Starter/Generator to cool after having been used as the Starter before you loaded it as the Generator.

[Brilliant Stuff]

That's what I seem to remember.

[heliPilotCadet]

thanks a lot