Pt6a-67d Trouble Shooting
 

Hello guys
What are the causes of fuel flow fluctiations during ground runs with a Beech 1900D,and then again during flight tests we get torque fluctiations coupled with NG fluctiations.Could the F.C.U be the prime suspect here?

Hi
Both the FCU or the High Press Fuel Pump could cause this.
In your troubleshooting I would start swapping the high press fuel pump between the two engines. I you don’t change any of the FCU connections this can be done without any rigging.
If this doesn’t move the problem I would continue with the FCU.

Thanks ECTM
We have managed to sort out the torque fluctiations,we replaced then F.C.U and fuel pump which helped,although we still getting slight fluctiations in NG of about 3%,i know it is low but you know how pilots can be.What is the possibility of the flow divider causing the slight fluctiation,or the airframes fuel pump,or even the airframe rigging?
Thanks again :ok:

have you tried the hp and lp bleed valves. there is a test but you need quite a big guy for the hp, if he is to stand nearby for the test, if not just transpose between the engines and see if the fault follows. 3% may be nothing much at idle but a t/o 3% is quite alot.

N1 fluctuation
 

As Blackhandler is writing it could be the bleed valves to check this you have the closing point check (Bubble check) in the P&WC EMM. My experience however is that BLV problems is affecting all the parameters and normally result in lack of power. However the check is quick and easy.
As for the flow divider once the engine is started and in idle the flow divider has done it's job. Normally problems with it would be hung start or very slow acc. during startup.
If you are sure that the N1 is the only fluctuating parameter and the ITT and FF is steady I would say it's an N1 indication problem. Try swapping N1 gauges and after that the N1 tacho gen.
Does the aircraft have an ADAS+ system installed? If it have you are welcome to send me the download from it for a quick analysis...fee of charge

not sure, but does the 1900 have a torque limiter. fluctuating tq n1 and wf (well wf may be constant) could also be this as it bleeds off py to limit tq by slowing n1 by droping wf