Power Levers Mismatch on a Twin Eng Turboprop

[asif ali]

Hi!

If any body can help me on this as i am new to Turboprop as maintenance incharge:

One of my aircraft (BN Islander with Allison 250 B17) i found mismatch of power levers at takeoff torque value. Till groung idle, the difference is not much but as the power is increased the right (engine) power lever needs slightly more and more push ahead to get same torque as the left one.
At takeoff power the difference is too much for pilot to control both the power lever with one hand. The fuel flow rate of right engine is also higher than that of left engine.

[Kengineer-130]

How are the TIT values? With a power lever mismatch, it generally means that one engine is working harder for it's power, and is suffering from an air leak or turbine/compressor problem. I have no experience on type, but I assume it is a constant speed TIT regulated engine? Does it have any bleed air systems?

[asif ali]

TGT is normal and within green arc. Your assumpition is right it is constant speed and TGT regulated. Engine has bleed air system.

[kingstonboy]

TGT within limits, how about Fuel flow ?i am assuming it is higher.Prop CSU function checked ? You mention bleed system (i have no experience on type and very rusty on turbo props) have leak checks been carried out ? Boroscope,comp washing(to help recover tgt margin),if all fails the relevant AMM,FIM or engine manufacturer may offer some suggestions .

[asif ali]

Ya fuel flow of engine under question is higher. Can u plz explain to me prop CSU function check?????
CSU?????

[spannersatcx]

have a look here

[sycamore]

Ali, it may well be worth a rigging check at all points of both power levers,and checks for loose/worn bearings on bellcranks/tension on cables etc (just guessing as I have no specific system knowledge).just don`t assume one engine is better/worse than the other...Then check the engine fuel controls,then any bleeds,as it doesn`t take much to lose power on a small t/prop.Don`t know what you do for comp washing but we used crushed walnut shells for helo compressors,to restore/maintain power.
Another would be a good check on blade(prop) condition,and range function/rigging...
Finally/or even firstly,a crosscheck of the instruments/ie calibration,state of thermocouples could help as well....ps not an engineer ,but was a maintenance test-pilot for many years...

[kingstonboy]

pcu,csu prop control system.However as fuel flow is higher the levers are,probably, telling the truth .In as much as to acheive like power settings different throttle settings are required. Out of interest how long has the offending engine been on wing in comparison to its partner ?

[asif ali]

Sycamore! thnx for the comprehensive list of checks in this regard. I will re-view the same in next run

Kingstonboy! Both the engines have consumed same life

[good spark]

asif ali i feel sorry for the poor souls who you are going to put in a a/c that you dont have a clue as to the serviceability of said machine, i think you should go and sit in the corner on your hands



gs

[Geepers Eprs]

TGT

Maybe the indicated TGT is not correct - the higher fuel flow and throttle displacement tell a story ????

[Saint Jack]

Power Levers Mismatched on a Twin Engine Turboprop

good spark: Your post was a bit harsh, wasn't it. The guy has identified a problem with his aircraft and taken note of the associated instrument readings and symptoms. Now he's looking for assistance to interpret these facts and determine corrective action - hardly "...you dont have a clue as to the serviceability of said machine..." in fact it's quite commendable initiative on his part. As for "...I think you should go and sit in the corner on your hands..." well this remark is pure childishness, isn't it.

asif ali: Contact Mr. Andy Howe who is the BN2T expert at PBN, the manufacturer (check their web-site), he'll be happy to assist you. For the benefit of others - including 'good spark' - let us know what the problem and corrective action was.

[good spark]

saint jack
i stand by what i said, it seems this guy is in charge of some sort of maint outfit?? and he resorts to asking total strangers on a internet forum about how to fix this defect , if you think thats ok fine, i think asif ali is a ####



gs

[asif ali]

Good Spark!

I thank you for your remarks and will say nothing else. I still considered it good to get opinion of experience hands although i had my paln and a list of corrective actions that was suppose to be the remedial steps but still i believe that
"There is no short cut to experiece".
I will advice u to broader your mind and insight.

And to all others thanx for the helpful remarks!!!!

I got the problem solved. It was basically cordinator assembly whose setting was out and mismathed. By syncronising them, the power levers are now working fine at all power levels.

[heated ice detector]

I was reading this post thinking how great it is that fellow engineers are always willing to help like minded others, then I read the post from great spark. good on you Asif Ali for fixing the prob and letting us all know

[asif ali]

Welcome Heated Ice Detector!

In fact this was my first time participating in any forum, I really appreciate the contribution of fellow engineers.

[markmylollypop]

whoever suggested the rigging process may have found the answer to you problem

when your rigging both levers the adjustment rings bring you 0.2mm closer to the correct reference angle from the cla to the pla adjustment angle or visa versa however this reference/adjustment is essently shunted from the opposing adjustment/reference with each clockwise turn of the adjustment ring, take a small/medium size elastic band, break it and use it on the teeth of the adjustment ring under the lever arm, dont be afraid to push the lever arm down onto it as much as possible without catching it or getting it stuck, this will show you time and time again that you have your adjustment ring correct when you think you have, glide the rigging in and bed it down