JC P-80SE WOn't accelerate in Hot Weather!!!!
07-26-2019, 06:37 PM
#1
JC P-80SE WOn't accelerate in Hot Weather!!!!
I have a Jet Cat P-80SE, that won't accelerate when I go to full throttle. It pops and snaps but won't accelerate when the temperature is above 95º and the humidity is high. This turbine just got back from the service
center last fall and has 17 flights on it. Anyone have any suggestion on what I should look for?
Thanks,
Larry /Instructor
center last fall and has 17 flights on it. Anyone have any suggestion on what I should look for?
Thanks,
Larry /Instructor
07-27-2019, 02:04 PM
#4
Thanks
Larry/Instructor
Last edited by Instructor; 07-27-2019 at 02:06 PM. Reason: spelling
07-28-2019, 08:15 AM
#7
A few years back a number of us went to an event in Cayley Alberta (Canada). We were used to flying at near sea level and Cayley is about 3500'asl as I recall. Early in the day when it was only around 75F we didn't really notice much difference with the engines, as the day rolled on and we approached 100F we started seeing engines that would "hang" at idle. I had a G Booster 160+ that did this, there were a number of Jetcats that did it, and a couple of other brands. Even my trusty old AMT Pegasus did the same thing. We found that if we were just slower moving the throttle stick they would accelerate. Not ideal but it worked. It changes the density altitude, I can't remember what it was exactly but the number 6600'asl for the temps and humidity sticks out in my mind for some reason. Next day when it was cooler in the morning the problems went away again. Then as it heated up they reappeared. Wouldn't have thought it would make that much of a difference but it sure did.
08-10-2019, 10:25 AM
#11
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I have a P80SE in a boomerang and I have flown it in 100 degrees weather in Hollister California and I had no issues with the turbine. I will say I typical only throttle up 1/4 of the stick when starting to take off and 20 feet later I go to full throttle. The airliners do the same thing on take off, but that is mainly for FOD issues. Remember turbines have a power curve that resembles an expo curve when going from idle to actual useable power.
08-10-2019, 10:59 AM
#12
I have a P80SE in a boomerang and I have flown it in 100 degrees weather in Hollister California and I had no issues with the turbine. I will say I typical only throttle up 1/4 of the stick when starting to take off and 20 feet later I go to full throttle. The airliners do the same thing on take off, but that is mainly for FOD issues. Remember turbines have a power curve that resembles an expo curve when going from idle to actual useable power.
Larry/Instructor
08-10-2019, 05:38 PM
#13
"sit at idle for 90 seconds, then it would accelerate." That actually sounds more like a Learn Low problem usually caused by the pump not producing a stable idle rpm for the ECU to pass control to the receiver. Watch the rpm on the GSU to see how stable it is after start. I've seen not so good pumps do +/- a couple thousand rpm. Once the ECU has decided idle is stabilized it will give the green Ok led on the GSU or I/O board which says you have control. On a P-80 the pops or snaps are tiny fuel droplets from the fuel needles "exploding". Pretty common.
08-19-2019, 07:18 AM
#14
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I have the same problem with my p60se propane start. I have it set to very slow and it still does it. Most of the summer here has been hot so it’s been annoying, at times can’t use it, and have had some dead stick
landings also.
landings also.
09-09-2019, 11:22 AM
#16
Please look at pump pressures. If the pump pressure is at or close to maximum voltage, the fuel system is clogged or pump is bad. We fly in 90+ wx in Florida, or you don’t fly. I was having slow acceleration and a couple flame outs. The fuel pump was the issue. I replaced the fuel pump after making sure that the fuel system was clean and flowing well. Just by changing the UAT bag, and a clunk filter, the voltage dropped below maximum. Replaced the fuel pump and haven’t had a issue. The weakness of the pump shows up in higher temperature.
Last edited by RCFlyerDan; 09-09-2019 at 12:06 PM.
09-10-2019, 05:44 AM
#17
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Please look at pump pressures. If the pump pressure is at or close to maximum voltage, the fuel system is clogged or pump is bad. We fly in 90+ wx in Florida, or you don’t fly. I was having slow acceleration and a couple flame outs. The fuel pump was the issue. I replaced the fuel pump after making sure that the fuel system was clean and flowing well. Just by changing the UAT bag, and a clunk filter, the voltage dropped below maximum. Replaced the fuel pump and haven’t had a issue. The weakness of the pump shows up in higher temperature.
Really appreciate the help here, I will look into this issue.
09-10-2019, 07:20 AM
#18
I don’t have an 80, so go to your Min/Max menu. Under fuel pump maximum increase the voltage to as high as it will allow you. It may already be there. Then go to your Run Menu to look at current or last fuel pump voltage. If they are the same or close, check the fuel system first, since it is the cheapest fix. Do a new run to 100% thrust for a couple minutes. If you replaced the UAT bag and other filters, then the fuel pump has to have time to adjust for the new fuel flow resistance. Voltage still high, swap a spare pump out to see if the issue went away. If you don’t have a pump in stock, maybe a buddy has one to try before buying one. But, I am almost certain that this is the issue.
Last edited by RCFlyerDan; 09-10-2019 at 09:49 AM.
06-29-2022, 08:46 AM
#23
Hi Everyone, and thanks for your advice. I recently run into this same problem again, high humidity and high temp. The idle setting was set to normal and so was the throttle response. I have set the Idle to slow and the throttle response to normal. Right now, the turbine runs great, but the weather is cool again, so I have to wait till we have a high humid day again..
Larry
Larry
08-21-2022, 06:35 PM
#25
Please look at pump pressures. If the pump pressure is at or close to maximum voltage, the fuel system is clogged or pump is bad. We fly in 90+ wx in Florida, or you don’t fly. I was having slow acceleration and a couple flame outs. The fuel pump was the issue. I replaced the fuel pump after making sure that the fuel system was clean and flowing well. Just by changing the UAT bag, and a clunk filter, the voltage dropped below maximum. Replaced the fuel pump and haven’t had a issue. The weakness of the pump shows up in higher temperature.
thanks,
Larry