pjvr99 Posted June 13, 2010 Share Posted June 13, 2010 Hey HerkyWorld Got an unusual situation here. Engine starts normal, LSGI torque set correctly. When the LSGI button is pulled to upshift to Normal Ground Idle, torque stabilizes for a moment at +-1200"lb ........ then increases to +-6000"lb, rpm decays to 94%, and TIT increases. Also prop noise indicates the engine is labouring. When LSGI button is pushed in, everything returns to normal. Standing on the blade line, you can see the pitch change occurring. Changed out valve housing, pitchlock regulator, and low pitch stop. Also removed all cannon plugs to remove electronic influence - no good! Stays the same ..... Anyone out there seen this before? any ideas, theories ........ anything? Have a great day PJ Quote Link to comment Share on other sites More sharing options...
keepemflying130 Posted June 19, 2010 Share Posted June 19, 2010 Nice one PJ. I know you know you stuff. It is the lack of electronics, and the actual increase in blade angle that get me. I'll think on it. Don't fix this sucker and leave us hanging. Quote Link to comment Share on other sites More sharing options...
Steve1300 Posted June 19, 2010 Share Posted June 19, 2010 To clarify the problem, let's see if I can restate this more in the terms that I think of this system: At approximately 72%, everything seems fine - even if left at 72% for a couple moments? However, when brought to approx 97%, torque moves from the normal level of 1200 pounds or so momentarily and the climbs up to a value that overloads the engine and RPM decreases to 94%. The only apparently influence that causes this is RPM? Somehow, hydraulic pressure is getting out to the dome and pushing the blades to increase pitch - but only at normal ground idle RPM. The normal increase-pitch pathway of fluid has been replaced (valve housing). The normal source of this pressure fluid has not (pressurized sump and pump housing pumps). Is it possible that there is a crack (or check valve) in the pump housing that allowed pressurized fluid to make its way into the side of the dome that increases pitch - as in a backflow of some sort? I think I'd be removing the pump housing and applying a strong light and magnifying glass to this pump housing. Somewhere, the return fluid from the dome may be backing up the return fluid from the dome and actually pushing fluid to the dome. I say that only because the other sealed areas that separate pressure fluid chambers has already been replaced. I definitly would like to know what you find. I may never see it or hear of it again, but I might remember this one for a long time. Quote Link to comment Share on other sites More sharing options...
tenten Posted June 19, 2010 Share Posted June 19, 2010 What’s raised by “Steve1300†---- “Make sense†Guys of the herk…, we start zooming. Quote Link to comment Share on other sites More sharing options...
mechanic80 Posted June 19, 2010 Share Posted June 19, 2010 cleaning of 14th stage bleed air filter and CIP blowing might help...if problem persists do a ground run in mechanical governing...adjust mech gov from FCU if problem shows in mech gov... Quote Link to comment Share on other sites More sharing options...
Herc 308 Posted June 22, 2010 Share Posted June 22, 2010 If it helps you try looking at your bleed pucks. Do a flag check to see if they are closing, sounds to me that might be the problem. Darrell Quote Link to comment Share on other sites More sharing options...
pjvr99 Posted June 22, 2010 Author Share Posted June 22, 2010 Ignore this thread, it somehow got duplicated. The real thread is here http://herkybirds.com/forums/showthread.php?t=1985 For info, the problem is definitely NOT on the engine. We ran it with another prop without any hassles. The problem prop received a valve housing removed from a tear-down, and quite happily made the seal break-in run for another engine this morning Quote Link to comment Share on other sites More sharing options...
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