Shola

Hello experts. We also have an APU that quits after running for about 8 minutes. Any idea what could be responsible for this discrepancy?

We replaced both the aux start relay and the fuel holding relay. We also replaced the centrifugal speed switch (110% overspeed switch). We heard the ignite firing. We even saw the spark before installing it back into the combustion chamber. During one of the attempts, the APU rpm rose to 32% and got stagnated. The combustion chamber was also hot indicating some combustion. However, the APU couldn't self sustain its operations. We have replaced virtually every component from FCU to oil pump to atomizer. We are however not sure of the integrity of the ignite as we do not have a new one in store. We have placed order for new ignitors for further troubleshooting. Thank you all for your contribution. I think we all can learn one or two things from this experience after we might have succeeded. Meanwhile, kindly keep your suggestions coming.

Thank you very much. We replaced the atomizer. We will replace the auxiliary start relay.

Hello guys. GTCP85-180L does not fire. It does not go beyond 20% rpm and there is no combustion. We have replaced FCU, oil pressure switch, oil sequencing switch, centrifugal switch, igniter plug, exciter yet no combustion. It just rolls but never achieves combustion. Any help please.

Thanks for the diagram

Thank you very much.

Thank you very much. I saw a diagram of the valve housing showing air start switch. Hence, my curiosity.

I know there is an air start switch in the valve housing. Could this be the cause of the engine failing to air start? Can anyone explain the function of the Air Start switch in the valve housing. Thanks.

Hello We just completed the ground run. The fuel enrichment system worked ok. Engine rigging ok. Engine performed well during ground running. What else could likely be the problem? Thanks for your time.

Forgive me for the mistake. I actually wanted to refer to the main RGB scavenge pump. The nose scavenge pump is probably to remove oil back to reservoir when the aircraft is nose down. If the fault is with the main or nose RGB scavenge pump, then, it was a good decision sending the engine for general overhaul.

This problem you described could be as a result of bad oil tank cap. Many a times, the gasket for the oil cap may be worn or the cap not properly locked in place. During flight and with pressure differential between inside the oil tank and outside the tank, coupled with the venturi effect of the drain system, oil could be sucked from the reservoir to the drain during flight. Another possible cause might be a failed RGB external scavenge pump. Unfortunately, the overhaul centre might not tell you the real problem.

We had a similar problem on our aircraft. The engine was dumping oil in flight. Using ghe Lockheed Service News pjvr99 spoke about, We ascertained that the problem was due to oil accumulation in the accessory drive housing. As recommended by the Service News, We ran the engine at cruise power for 30 minutes. At the 29th minute, there was oil dumping as highlighted in the Lockheed Service News. We therefore confirmed that the problem was due to inadequate scavenging of oil back to the reservoir. You need to run the engine for minimum 30 minutes for the dumping to begin. We replaced the main engine oil pressure pump as well as the external scavenge pump, both on the accessory drive housing. Please note that you must bleed the main oil pumpbafter installation by loosening the back vent of the pump and then motoring the engine until oil gushes out of the bleed point. This procedure solved the in-flight oil dump in our case. You may wish to try same.

The connector to one of the blade antennas on the vertical stabilizer was found removed. Connector tightened back and system checked and found ok. Apparently, there was no signal from one of the 2 antennas to the receiver.

60% rpm. Suddenly, engine wound down with all other parameters following. Remember that after landing, engine started normally

Please i need help. #2 Engine failed to air-start. Engine wound down from 60 percent rpm. On landing, engine started normally. NTS switch and NTS brackets checked ok. Pump housing oil quantity normal. Need help to rectify the fault. Thanks.

Hello NATOPS. Surprisingly, the throttle creeping has stopped after we swapped the engines. The aircraft has been scheduled to go for functional check flight. I will let you know the outcome of the FCF. Thanks.

Gentlemen, I regret to inform you that after ground run of the engines, the creep came back. This is even after replacing the valve housing cover. Our next plan is to swap engine 1 and 4 to see if the problem will transfer.

Thank you all for your suggestions. Based on your advise, we replaced the gimbal assembly and carried out rigging of the propeller. The throttle lever creeping has stopped. Again, thanks for your time.

Thank you very much.

Thank you very much. We will install a new gimbal assembly this morning. I will let you know the outcome. Once more, thanks a million.

Please i need help. We recently encountered an uncommanded movement of the #4 engine throttle lever from ground idle to just before the gate of flight idle. We checked and confirmed that the cable tension is ok. We also cleaned and greased all bell-cranks. Yet, the problem persists. Once the throttle is moved from the ground idle, it creeps forward until it reaches the gate of flight idle. Any advise would be appreciated. Thanks.

Thanks.

Thank you very much Casey. It is true I am relatively new here compared to tinyclark who has been a member since inception. Nevertheless, I take exceptions to someone asking me derogatory questions. Read his comments again and read Larry Myers objective intervention. I still believe tinyclark was unfair to me. I am here to learn and not to cause drama. Furthermore, it is not all on this forum that have English Language as their mother tongue. I think the warning is more applicable to him and not to me.

Thank you very much Larry Myers. Tiny's question sounds very insulting to say the least. All he needed to do was consult Oxford English dictionary.