pmostafiz Posted August 14, 2019 Share Posted August 14, 2019 7b engine: #2 engine rpm fluctuation about 1% during decending and when goes through the weather. NTS gap is OK and plunger looks good. Any experience about this? Quote Link to comment Share on other sites More sharing options...
pjvr99 Posted August 14, 2019 Share Posted August 14, 2019 if by weather you mean cloud or rain, changes in air density going into compressor will be detected by fcu cip & cit probes. as the throttle is already pulled back, a weak valve housing may not be able to hold the rpm steady. 1c-130h-2-71jg-00-1 gives rpm 1.5% total travel with throttle below flight idle, and 1.0% with throttle above x-over and more than 8000"lb torque. valve housing change is the quicker fix, but you may end up changing fcu. as an after-thought, check the time on dome quad-seals. Quote Link to comment Share on other sites More sharing options...
pmostafiz Posted August 14, 2019 Author Share Posted August 14, 2019 Thank you pjvr99. By weather I meant cloud. Every time during decending rpm travel 99.5 to 100.5 at all modes with frequency. Fuel flow and tit stable and no fluctuations. Did you mean bellow crossover 1.5 total travel allowable? If it is can you send me a screenshot or if you can send me to [email protected]. If fuel flow and tit stable, should I go to Fcu? I am thinking about V/H. What is your opinion? Quote Link to comment Share on other sites More sharing options...
pmostafiz Posted August 14, 2019 Author Share Posted August 14, 2019 1 hour ago, pjvr99 said: if by weather you mean cloud or rain, changes in air density going into compressor will be detected by fcu cip & cit probes. as the throttle is already pulled back, a weak valve housing may not be able to hold the rpm steady. 1c-130h-2-71jg-00-1 gives rpm 1.5% total travel with throttle below flight idle, and 1.0% with throttle above x-over and more than 8000"lb torque. valve housing change is the quicker fix, but you may end up changing fcu. as an after-thought, check the time on dome quad-seals. Thank you pjvr99. By weather I meant cloud. Every time during decending rpm travel 99.5 to 100.5 at all modes with frequency. Fuel flow and tit stable and no fluctuations. Did you mean bellow crossover 1.5 total travel allowable? If it is can you send me a screenshot or if you can send me to [email protected]. If fuel flow and tit stable, should I go to Fcu? I am thinking about V/H. What is your opinion? Quote Link to comment Share on other sites More sharing options...
pmostafiz Posted August 14, 2019 Author Share Posted August 14, 2019 Quote Link to comment Share on other sites More sharing options...
pjvr99 Posted August 15, 2019 Share Posted August 15, 2019 yes, thats it. if your rpm flux is only +-0.5 you appear to be within limits. however, if the crew is uncomfortable you will have to do something. out of curiousity, did you do a fuel governing and pitchlock check? Quote Link to comment Share on other sites More sharing options...
pmostafiz Posted August 15, 2019 Author Share Posted August 15, 2019 9 hours ago, pjvr99 said: if by weather you mean cloud or rain, changes in air density going into compressor will be detected by fcu cip & cit probes. as the throttle is already pulled back, a weak valve housing may not be able to hold the rpm steady. 1c-130h-2-71jg-00-1 gives rpm 1.5% total travel with throttle below flight idle, and 1.0% with throttle above x-over and more than 8000"lb torque. valve housing change is the quicker fix, but you may end up changing fcu. as an after-thought, check the time on dome quad-seals. 1 hour ago, pjvr99 said: yes, thats it. if your rpm flux is only +-0.5 you appear to be within limits. however, if the crew is uncomfortable you will have to do something. out of curiousity, did you do a fuel governing and pitchlock check? Fluctuations allowable, above crossover: 1.5 Below flt idl: 1, what is allowable range of below crossover?? Because during decending throttle remain in-between flt idl and crossover. I did not do pitchlock Ckeck. Can you describe for my understanding why it is important as everyone rpm stable and only fluctuates during decending. Thanks Quote Link to comment Share on other sites More sharing options...
Ahmer Posted August 15, 2019 Share Posted August 15, 2019 20 hours ago, pmostafiz said: 7b engine: #2 engine rpm fluctuation about 1% during decending and when goes through the weather. NTS gap is OK and plunger looks good. Any experience about this? Hello, at that time ur prop is in normal governing mode or in mechanical mode? If fluctuation is in both modes then change v/Housing filter and then valve housing. Most probably cause of valve governor. Regards Quote Link to comment Share on other sites More sharing options...
pmostafiz Posted August 16, 2019 Author Share Posted August 16, 2019 15 hours ago, Ahmer said: Hello, at that time ur prop is in normal governing mode or in mechanical mode? If fluctuation is in both modes then change v/Housing filter and then valve housing. Most probably cause of valve governor. Regards Every time during decending rpm travel 99.5 to 100.5 at all modes ( Mechanical and normal mode even synchrophaser off) with frequency. Fuel flow and tit stable and no fluctuations. Rpm stable at level flight and on ground. Quote Link to comment Share on other sites More sharing options...
Ahmer Posted August 16, 2019 Share Posted August 16, 2019 (edited) 43 minutes ago, pmostafiz said: Every time during decending rpm travel 99.5 to 100.5 at all modes ( Mechanical and normal mode even synchrophaser off) with frequency. Fuel flow and tit stable and no fluctuations. Rpm stable at level flight and on ground. If fluctuation is in all modes,Most probably cause of valve housing. Edited August 16, 2019 by Ahmer Quote Link to comment Share on other sites More sharing options...
superbigbig Posted June 10, 2020 Share Posted June 10, 2020 On 2019/8/16 at AM11點56分, pmostafiz said: 檢查頻率表有沒有跟著擺動,可能是指示器故障 Quote Link to comment Share on other sites More sharing options...
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