P-120 overspeed Flameout
 

I already posted this on the Jet Cat Forum but am looking for other opinions

My flying buddy maidened his Ultra Flash on Saturday with a P120 in it. He did a full run up to full power with the GSU connected and confirmed the max RPM @123K. He also did full range checks with and without the Turbine running.

Take off roll and lift off were picture perfect, he executed a turn to downwind, flew about another 800 feet and the engine just shutoff, no smoke.

Plugging the GSU in after a safe landing, he observed the Hi RPM to be 142,300. Max pump Voltage was 2.5V. Cause for shutdown was Overspeed.

A subsequent run on the ground indicated a solid 123,000.

My question is this. Is 2.5V Max pump Voltage normal on a P-120?

I'd like to hear from guys that actually check theirs after they fly.

TIA

Bob

RE: P-120 overspeed Flameout
 

Is this a old P-120 with optic sensor or hall effect RPM sensor?

RE: P-120 overspeed Flameout
 

2.5 V is not really unusual :eek:
mine at full rpm is 2.4 V.

RE: P-120 overspeed Flameout
 

Bob

No, a simple look at the voltage while running at 123,000 would have shown you 3.8-3.9v. This all depends on how free the fuel system is. Each size of JetCat P-60/70/80/120/160 shows increases in the max voltage from around 2.6v on the P-60 to 4.2v on the P-160.
I replied to him to check the black wire, it takes the rpm signal and I'm guessing made a bad contact. The 2.5v would have been as the turbine slowed to stop.

Dw

RE: P-120 overspeed Flameout
 

I believe it's a Hall-effect.

RE: P-120 overspeed Flameout
 

On a P-120? Really? Never seen anything that low.

Dw

RE: P-120 overspeed Flameout
 

Well guys and Dave thanks for the help. decided to send turbine/ECU to jetcat for a checkup. My Friends at Fedex are bringing it to the loving hands of jetcat as we speak. After the flameout we changed the ECU and turbine to a P-80 SE. We now have 8 great flights on the U-flash without misshap! Couldn't see anything wrong but as a precaution I have replaced both ends of the RPM black cable! Foolishly we didn't check all the readings on the GSU and re-ran the motor on the ground following the event.It ran perfectly....but now I think all the info that could have been used from the ECU is gone : ( Hopefully jetcat can diagnose the problem!
Thanks agian
Brian : )

BTW off subject Love the U-Flash and the P-80 SE really scoots it along!....when then 120 returns....it should be even better!

RE: P-120 overspeed Flameout
 

I will speak to Wilcox in the next day or so and I will follow up, PM me your SN or name and I can ask for you.

I agree, 2.5 volts does not sound right. The max voltage would be much higher to truely drive the RPM that high. Unless it is a sensor problem of some kind and it did not really hit that high rPM

RE: P-120 overspeed Flameout
 

Interesting thread, my first P-120 (almost 10 years ago now) self destructed in flight at very low hours on the engine. Takeoff was fine but when I went to cut back on the power in the turn F/T stayed on and in fact kept increasing until the engine self destructed due to a failed bearing, jamming the compressor to stop the engine resulting in raw fuel being dumped out the back of the engine and an ensuing inflight fire which blew itself out by the time I got the thing back on the ground. This particular engine was shipped back to Germany (at their request) by Bob and resulted (I'm told) in some changes to the software at the time to prevent a reoccurence. I was told that final rpm was just under 150K.

Still running 2 - P-120 SE's.....the one I ran yesterday was running 2.4volts at 123K.

RE: P-120 overspeed Flameout
 

Matt, I was there when the U-Flash flamed out. Bri has fun it full throttle on the ground (short periods) with no problems... on the first flight, after rotation and going into a right turn, the engine quit....