txshan130

My Feedback: (114)

Hey Everyone -

Had a flameout recently on a P120SX that has never had an issue before..The turbine itself is getting up there but the pump is relatively new. Anyway, after about 1.5 laps at 3/4 throttle, it flamed out. Here is the downloaded data:

[TABLE="class: grid, width: 500"]
[TR]
[TD]Time[/TD]
[TD]RPM[/TD]
[TD]Set RPM[/TD]
[TD]EGT[/TD]
[TD]PmpV[/TD]
[TD]Sta[/TD]
[TD]Thr[/TD]
[TD]Bat[/TD]
[/TR]
[TR]
[TD]-4.4[/TD]
[TD]82[/TD]
[TD]93[/TD]
[TD]416[/TD]
[TD]2.1[/TD]
[TD]11[/TD]
[TD]76[/TD]
[TD]8.1[/TD]
[/TR]
[TR]
[TD]-4.2[/TD]
[TD]84[/TD]
[TD]93[/TD]
[TD]417[/TD]
[TD]2.1[/TD]
[TD]11[/TD]
[TD]76[/TD]
[TD]8.1[/TD]
[/TR]
[TR]
[TD]-3.0[/TD]
[TD]93[/TD]
[TD]94[/TD]
[TD]424[/TD]
[TD]2.3[/TD]
[TD]11[/TD]
[TD]76[/TD]
[TD]8.1[/TD]
[/TR]
[TR]
[TD]-2.8[/TD]
[TD]94[/TD]
[TD]94[/TD]
[TD]425[/TD]
[TD]2.3[/TD]
[TD]11[/TD]
[TD]77[/TD]
[TD]8.1[/TD]
[/TR]
[TR]
[TD]-2.6[/TD]
[TD]93[/TD]
[TD]95[/TD]
[TD]424[/TD]
[TD]2.3[/TD]
[TD]11[/TD]
[TD]77[/TD]
[TD]8.1[/TD]
[/TR]
[TR]
[TD]-2.4[/TD]
[TD]91[/TD]
[TD]95[/TD]
[TD]422[/TD]
[TD]2.4[/TD]
[TD]11[/TD]
[TD]77[/TD]
[TD]8.1[/TD]
[/TR]
[TR]
[TD]-2.2[/TD]
[TD]87[/TD]
[TD]95[/TD]
[TD]418[/TD]
[TD]2.4[/TD]
[TD]11[/TD]
[TD]77[/TD]
[TD]8.1[/TD]
[/TR]
[TR]
[TD]-2.0[/TD]
[TD]75[/TD]
[TD]95[/TD]
[TD]405[/TD]
[TD]2.1[/TD]
[TD]11[/TD]
[TD]77[/TD]
[TD]8.1[/TD]
[/TR]
[TR]
[TD]-1.8[/TD]
[TD]60[/TD]
[TD]95[/TD]
[TD]386[/TD]
[TD]1.7[/TD]
[TD]11[/TD]
[TD]77[/TD]
[TD]8.1[/TD]
[/TR]
[TR]
[TD]-1.6[/TD]
[TD]47[/TD]
[TD]95[/TD]
[TD]366[/TD]
[TD]1.4[/TD]
[TD]11[/TD]
[TD]77[/TD]
[TD]8.1[/TD]
[/TR]
[TR]
[TD]-1.4[/TD]
[TD]38[/TD]
[TD]95[/TD]
[TD]347[/TD]
[TD]1.2[/TD]
[TD]11[/TD]
[TD]77[/TD]
[TD]8.1[/TD]
[/TR]
[TR]
[TD]-1.2[/TD]
[TD]32[/TD]
[TD]95[/TD]
[TD]329[/TD]
[TD]1.1[/TD]
[TD]11[/TD]
[TD]77[/TD]
[TD]8.1[/TD]
[/TR]
[TR]
[TD]-1.0[/TD]
[TD]27[/TD]
[TD]95[/TD]
[TD]313[/TD]
[TD]1.1[/TD]
[TD]11[/TD]
[TD]77[/TD]
[TD]8.1[/TD]
[/TR]
[TR]
[TD]-0.8[/TD]
[TD]24[/TD]
[TD]95[/TD]
[TD]299[/TD]
[TD]1.0[/TD]
[TD]11[/TD]
[TD]77[/TD]
[TD]8.1[/TD]
[/TR]
[TR]
[TD]-0.6[/TD]
[TD]21[/TD]
[TD]95[/TD]
[TD]286[/TD]
[TD]1.0[/TD]
[TD]11[/TD]
[TD]77[/TD]
[TD]8.1[/TD]
[/TR]
[TR]
[TD]-0.4[/TD]
[TD]19[/TD]
[TD]95[/TD]
[TD]275[/TD]
[TD]1.0[/TD]
[TD]11[/TD]
[TD]77[/TD]
[TD]8.1[/TD]
[/TR]
[TR]
[TD]-0.4[/TD]
[TD]18[/TD]
[TD]95[/TD]
[TD]266[/TD]
[TD]1.0[/TD]
[TD]11[/TD]
[TD]77[/TD]
[TD]8.1[/TD]
[/TR]
[TR]
[TD]-0.2[/TD]
[TD]82[/TD]
[TD]93[/TD]
[TD]416[/TD]
[TD]2.1[/TD]
[TD]11[/TD]
[TD]76[/TD]
[TD]8.1[/TD]
[/TR]
[/TABLE]


So you can see that at -2.6 seconds, the RPM starts to roll back...it looks like the pump voltage increases marginally and "tries" to correct the low RPM condition, but then at -2.2 seconds just starts falling off.

Any ideas why the pump voltage would fall off or what exactly that means or indicates? Is this indicative of a blocked fuel line perhaps (filter) slowing the pump down? Guess I'm not exactly clear on where that value is derived from...or even what a "normal" shutdown looks like when looking at pump values Any JC gurus know the answer before I send it in to Todd?

Also not sure about the last line at -0.2 seconds...seems like an anomaly perhaps...

Thanks for any help!

yeahbaby

My Feedback: (21)

You said it's a new pump, have you tried running it in? I.e. Hook up a battery to it and run a closed loop into fuel jug for about 5 minutes. Might help " break in " gears.

then hook it back into the jet and try to replicate above results. Ofcourse if inconsistent results occur, send it in or acquire another pump.

good luck

txshan130

My Feedback: (114)

Hey Buck...it's "relatively" new. Been used at LEAST 10 flights if not more with no issues - definitely broken in :-)

yeahbaby

My Feedback: (21)

Oki doki

wfield0455

My Feedback: (7)

What did the ECU say was the shutdown cause, LOW RPM ? If so I believe that means that it can't sustain RPM so it keeps increasing the pump voltage trying to increase the RPM to the desired level and if it can't do so by the time the pump voltage reaches some maximum value it assumes there is a problem and shuts the turbine down. The one time I had this cause for a flame out it was a fuel supply issue and my UAT was clogged and causing the problem. Solved the fuel flow issue and no more flame outs. This was also on a Jet that had been flown a number of times without any prior problems.

Wayne

bluescoobydoo

have you check the battery condition? is it failing under load might be a easy thing to replace just to rule it out, if not check fuel flow set up

Vettster

Yup.. back to basics..

Battery under load
Fuel filter?
Air bubbles
UAT leaking (several points there!)
Cavitation

Sell it and buy a Kingtech/JetMunt with auto-re start

Desertlakesflying

My Feedback: (28)

run 3/16" ID from clunk to pump. Fixed my P-120 flameout problem.

i3dm

My Feedback: (51)

what did the GSU say the reason for the flameout was?

Bobneal1

My Feedback: (21)

Looks like fuel problem to me , everything is stable , battery voltage is constant throughout the data . Was there any white smoke ? Pump voltage increases but rpm decreases , there is no fuel flow increase or the temp would increase unless you had a large air bubble in the line.

Jetkopter

My Feedback: (1)

I can already see that the reason for the shut down is low rpm. look at where the command rpm vs the actual rpm. As Bob said it was more than likely that it was and air bubble. Get your GSU, disconnect the fuel line from the motor and go into test function menu and you will see purge fuel system. Put the fuel line in a catch can and hit the change value key and the plus key and you can run the pump at max voltage to find any fuel system problem as this will simulate actual conditions during operation. If your sucking air you are sure to find it. The last line is more than likely an anomaly, but it would not hurt to spool the motor with the manual button and verify that rpm reading is steady and not jumping around.

franklin_m

Is there more data? I'm not a model jet guy, but I'm a retired military jet guy and a data analysis nerd. It would be interesting to see the variation of RPM, EGT, and PmpV for other portions of the flight, see what leads what, what trails what, etc.


What I saw is early on, is that between the first data point and the second one, there's a 2.4% increase in RPM. On the next data point (3rd), EGT is up 1.7%, PmpV is up 9.5%, and RPM up 10.7%. With small numbers and not sure of the precision of the measurements, this may not matter. The question is which parameter varied first? A larger data set, particularly earlier in the flight, might lend some insight.

I'm a visual analysis guy, I made these. May or may not be of help.

George

My Feedback: (57)

This appears to be the shutdown data. The last data line (anomaly) is actually the first data line of the set, but for some reason, it always ends up at the bottom of the data. If you were to download the log data, it would have the same "anomaly".

Bob and Don seem to be on the right track; and Don's suggestion of running the pump via the GSU is a good diagnostic procedure.

Thud_Driver

My Feedback: (1)

Yes, there is more data but you need to buy JetCat's PC software to access it. I believe the entire engine run is saved on the ECU.

The data says the battery was ok at 8.1 volts. This is likely an external cause like an air bubble in the line with the ECU probably showing a Low RPM shutdown. When the rpm gets low enough the ECU "gives up" and shuts the engine off via a solenoid and reports Low RPM.

The OP didn't say, but if there was white smoke at the time of shutdown, it was probably air. If no smoke, it was likely fuel starvation. Either way, the problem is likely in the fuel system.

txshan130

My Feedback: (114)

Ok...thanks all for the info. Never had a fuel problem with this setup for probably 75-100 flights at least, but perhaps could be a filter issue either in the UAT or the actual fuel filter itself. Will check those today and test run the pump via the GSU. FWIW, "low RPM" was indeed the reported shut down condition.

Ceeray

My vt80 shut down itself couple of times when reducing throttle to idle. Luckily this happened while taxiing.

Fault was at festo fitting, it leaked a bit and drew air into fuel line, without visible bubbles..

Jetkopter

My Feedback: (1)

When I do a new install in a model I always record the max temp and the max pump voltage and leave it on a piece of tape in the model. Makes it very easy to go back and check down the road if your pump is having to work harder to achieve the same rpm. Increasing temps is also a sign it time for service.

txshan130

My Feedback: (114)

Forgot to add...no white smoke.

Also - guess what still is perplexing to me is why the pump voltage decreases long before the shutdown. The shutdown probably occurred around the -1.0 second mark at around 27k rpm, whereas the pump voltage started decreasing a full second before that at around the -2.2 second mark. The ECU should have been commanding more fuel all the way until shutdown since the target RPM was always higher than the actual RPM...

Jetkopter

My Feedback: (1)

The low rpm shut down is a protection function of the ECU. The ECU reads the commanded Rpm vs the actual rpm and If the engine does not obtain that rpm is a given amount of time you get the low rpm shut down. The protection is because if a bearing where to go bad the ecu would try and pump more fuel to maintain rpm. The ECU does care why the rpm is low, only that it is and it cuts off the fuel.

txshan130

My Feedback: (114)

OK..that would make more sense. The pump voltage is a result of the ECU actually commanding a shutdown due to the low RPM situation. I was originally thinking the low RPM was perhaps initially "caused by" the low pump voltage.

Thud_Driver

My Feedback: (1)

Yeah, the pump voltage is a bit puzzling but I would guess from the RPM readings you were getting fluctuations before the last 4 seconds since the RPM was not stable. Certainly possible the impending flameout could have taken more than a couple seconds to develop. I don't know what engine State 11 is, but it doesn't change even though the ECU should have turned everything off around 24-27K rpm.

No smoke is a sign of fuel starvation. Possibilities include: a bad pump, the fuel solenoid shutting off, an empty UAT (caused by sucking air thru the fill tube or thru festo fittings), clogged filters (although in thousands of flights I personally have never seen this happen), kinked fuel line, vent line capped or blocked, failure to refuel/empty tanks, etc. Easy enough to check lines/UAT for lack of fuel.

Vincent

My Feedback: (61)

Could be static too

Thud_Driver

My Feedback: (1)

Static would typically give a "Watchdog" shutdown code.