PPRuNe Forums - View Single Post - Power levers on turbine helicopter
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Old 16th Apr 2013, 13:46
  #10 (permalink)  
HeliComparator
 
Join Date: Aug 2004
Location: Aberdeen
Age: 63
Posts: 2,021
I can't answer specifically for the Augusta nor the squirrel but in general:
Many thanks for the replies!

Just to clarify, when you start the first engine, do you have to advance he lever to the flight position prior to starting the other engine allowing the battery to recharge or you start the second engine with the other engine in idle? Normally you would go to flight position, as you say so that alternators come on line etc
When you start the engine do you select the idle position and then you let the fadec take care of the sequence while you monitor the engine for no light off, hung start, hot start, starter fail to disangage - those conditions stem from my jet flying background and i am not sure they apply to the helicopter as well! - or you start the engine with the lever in shutoff and then you advance it into the flight detent at a certain percentage of gas generator? Depends on type but on reasonably recent designs, you put the lever into idle. Earlier designs you typically left it in shutoff until a certain N1 was reached
During normal flight as the tl's are advanced into the flight detent, i presume just prior to takeoff, does the fadec or fcu maintain a constant rrpm's by mean of a governor and correlator as the collective is changed, varying the load on the mrs, if so which instrument do you refer to to set the power? Yes, although there can be static droop on some poorer designs as I previously mentioned. Power can be set by looking at torque, N1 or on some types, collective position. Whether torque or N1 depends on which parameter is the limiting one, which varies according to density altitude. Probably you then back it up with the engine temperature You need to check you are not above a limit, but on most types you should top out on torque or N1 first. Decent modern types have a "First Limit Indicator" that tells the pilot how far he can raise the collective before hitting the first limit, whether it be TOT, Torque or N1.
Do you have an APR postion - auxiliary power reserve - providing an uptrim either manually or automatically in case of an engine failure on the remaining engine? And if so, do you select it manually? Not APR as such, but on some old types yes, to counter the static droop at max OEI power you might beep the Nr up to a high value for takeoff and landing, so that the inevitable droop when OEI max power doesnt reduce the rotor rpm too much. Modern types dont suffer from static droop - the FADEC typically limits you to AEO power until an engine failure is detected, then it arms OEI power automatically.

Many thanks and my apologies for the lengthy post

Baobab72

Last edited by HeliComparator; 16th Apr 2013 at 13:47.
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