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Help diagnosing AMT flameout (pics)

Old 06-04-2012, 01:12 PM
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Dieselman1220
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Default Help diagnosing AMT flameout (pics)

Ok I spent a few weeks re plumping my entire YA F15, all new air lines, new fuel lines, new UAT, new smooth stop, etc etc. The airplane is about 6years old so it was overdue for all these things. I started up my AMT 280
at home twice running it for about 3-4 minutes both times just to make sure everything was ok. I got to the field Sunday morning and again started it up taxied it down the runway a few times did my range checks, re set my nose wheel steering
tested the brakes a few times then shut her down. So at this point ive got about 10-12 minutes of run time at various power settings. I recharged all my batteries fueled her up and get her ready to fly. Take off get her up to about 300 feet and enter a right pattern
on down wind i back it off to about half throttle and start trimming her out. on about the second pattern right as i start a left turn to enter my upwind (transitioning to left pattern) i hear the turbine spool down and go quiet. This particular flying sight is on a peninsula
so my immediate concern was keeping the airplane out of the water as id rather pick up pieces than nothing at all. It took about 2 or 3 seconds for my mind to register that that it actually flamed out on me. ive got about 60 flights on my tornado
with an amt180 and i guess ive fallen into a false sense of security that these things just dont quit.

I immediately put the nose down about 30 degrees and kept her in the left turn trying to keep it smooth and using just a hint of rudder to keep the turn going without losing to much energy. It just wasnt enough though i was able to gt her pointed back towards the runway and
away form the water but just lost way to much engery in the turn. Anyone whos flown an f15 knows it glides about as good as a shoe. in the last 80-100 feet I was able to get pointed at about a 45 degree angle back towards the runway but she was way to slow i pointed the nose down some
more with what little elevator authority i had and then tried just before hitting the tree line i gave it full up so it would pancake down so hard. It really didnt do any good as I had no more elevator authority. I found her about 400 yards away pointing the same direction. coming down though
the trees really tore up the wings and stabs. To my surprise everything was pretty ok turbine was fine, no fuel leaks, no ruptured tanks, both my brake and gear tanks still even had 100 psi in them, and i only killed 1 8411 servo in the horizontal stab.

the ECU was beeping with the low rpm warning so i immediately suspected the rpm sensor. when i got the wreckage back to the tables and plugged in my EDT i spooled her and I had RPM readout. I then suspected maybe the EGT probe, nope it was still in and reading correctly.
So im thinking maybe an air bubble, but I ran it for several minutes before so i think it should have purged out any air bubbles by then. Then i was thinking maybe some sort of debris in the fuel line caused a blockage. Well I got it home checked everything out again and decided to fire
up the engine. Started right up throttled up on command sat at full power for about a minute no problem at all??? so im at a loss now?? I dont know what could have caused the flameout, maybe it didnt like the vent system and the airflow caused some sort of venturi effect I just dont know.

So anyway Im pretty bummed I smacked my first jet, but I feel like I did everything I could given the circumstances. Even if I would have made it back to the clearing near the runway i wouldn't have had enough airspeed or elevator authority to arrest the high sink rate and she would have smacked down hard!.
So I welcome everyone to play NTSB investigator and try to figure out what happened. I havent dismantled anything yet so i would be happy to submit additional pictures of anything showing my set up and all. If nothing else I want this to be a learning experience to hopefully prevent
this from happening to me or anyone else in the future. And if anyone knows where there is another YA F15 ARF I desperately would like to replace mine.


Old 06-04-2012, 01:17 PM
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Dieselman1220
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Default RE: Help diagnosing AMT flameout (pics)

These pics are all from the same day






Old 06-04-2012, 01:19 PM
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Ruizmilton
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Default RE: Help diagnosing AMT flameout (pics)

Do you have an early two channel ECU or single channel?
Old 06-04-2012, 01:28 PM
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Dieselman1220
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Default RE: Help diagnosing AMT flameout (pics)

Its a two channel all three that I have two mercs and this peggy are 2 channel
Old 06-04-2012, 01:30 PM
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Kevin_W
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Default RE: Help diagnosing AMT flameout (pics)

Do you have a UAT (or similar air trap) installed?
If so, is it still full of fuel?
Old 06-04-2012, 01:35 PM
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Dieselman1220
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Default RE: Help diagnosing AMT flameout (pics)

Yes I put a brand new BVM UAT in it it still has fuel in it, I only drained the main tanks afterwards and when i started it again at home after the crash.
Old 06-04-2012, 01:55 PM
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Kevin_W
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Default RE: Help diagnosing AMT flameout (pics)

Did you see any puffs of smoke out the tailpipe when it flamed out? (sometimes impossible to see on cloudy or hazy days)

Since you had just re-plumbed the fuel system my first suspicion is that you probably had some air trapped somewhere, or there was a leak in the system on the intake side of the fuel pump.

If you have a leak in any of the lines between the main tanks and the UAT the UAT will usually end up full of air.
It is also possible to have an air bubble trapped in either the UAT or the filter that will remain stationary until the plane enters a different attitude, or some kind of vibration breaks it free. After a new install I always run the engine up to full power the shake the filter (or the whole airplane) vigorously to be sure there are no trapped bubbles left in the fuel system.
Old 06-04-2012, 02:22 PM
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CraigG
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Default RE: Help diagnosing AMT flameout (pics)


ORIGINAL: Kevin_W

Did you see any puffs of smoke out the tailpipe when it flamed out? (sometimes impossible to see on cloudy or hazy days)

Since you had just re-plumbed the fuel system my first suspicion is that you probably had some air trapped somewhere, or there was a leak in the system on the intake side of the fuel pump.

If you have a leak in any of the lines between the main tanks and the UAT the UAT will usually end up full of air.
It is also possible to have an air bubble trapped in either the UAT or the filter that will remain stationary until the plane enters a different attitude, or some kind of vibration breaks it free. After a new install I always run the engine up to full power the shake the filter (or the whole airplane) vigorously to be sure there are no trapped bubbles left in the fuel system.
Ditto what Kevin said. Every flameout I ever had with my AMT's (maybe half a dozen total over the years), could be traced to a fuel problem. The most common involved the UAT. The cap and center fitting need to be tightned with a pair of pliars until they bottom out. Sometimes a bubble will develop in the UAT, cause a flame out, and be gone after the fact.

Sorry that you damaged your jet and hope you figure out the cause.

Craig
Old 06-04-2012, 03:06 PM
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rcjetsaok
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Default RE: Help diagnosing AMT flameout (pics)

Bad deal for sure... My first thought was the same as yours... RPM sensor.. They are the Achilles heel of the AMT design... Optic not Magnetic and they slip in the mount and the Compressor chops off the tip... Had plenty of them do that... Since you got a restart that is out.. Your EGT theory is also out, because AMT does not monitor EGT after the start sequence is completed and cannot cause a shut down... So that pretty much leaves fuel... I would be suspicious of the fuel pump of you are confident there are no air leaks in the system. What happens is the seals in the pump fail and fuel gets into the motor part if the pump and causes it ti slow down or quit. I have had that happen before and it did restart and run normal.. I finally figured it out when I noticed the wires coming out of the pump looked swollen, and sure enough, there was fuel inside the insulation of the wires and the motor was of course soaked as well. Damnedest thing I ever saw... The pump still worked though but it was not well... I condemned the pump, and replaced it. The only other thing that comes to mind is to check the fuel fittings under the front cover and make sure they are tight and no leaks... You would never see that with out pulling the cover. Keep us posted !!!


Good luck !!!,

Danno
Old 06-04-2012, 03:13 PM
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G4guy
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Default RE: Help diagnosing AMT flameout (pics)

Quick question, what radio are you using and on the Transmitter, what lever are you using to control the ECU?
Ron
Old 06-04-2012, 05:39 PM
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Ruizmilton
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Default RE: Help diagnosing AMT flameout (pics)

Since you have a 2channel ECU, did you check no other switches are influencing your 3 position turbine start/stop/shutdown channel? I know it sounds obvious, did the shutdown occur after raising retracts or flaps? Just checking, you said you heard the turbine spool down, if it was a slow spool down it was not an air bubble...
Old 06-04-2012, 07:04 PM
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Default RE: Help diagnosing AMT flameout (pics)


ORIGINAL: Ruizmilton

Since you have a 2channel ECU, did you check no other switches are influencing your 3 position turbine start/stop/shutdown channel? I know it sounds obvious, did the shutdown occur after raising retracts or flaps? Just checking, you said you heard the turbine spool down, if it was a slow spool down it was not an air bubble...
That is similar to what happened to me when I switched from Futaba 72 to a 2.4 JR 9303. I had the 2nd channel controlling the ECU on the slider on the left hand side of the TX.
what i didn't know was that the ECU was seeing the "normal shutdown mode (Middle position)" almost next to the "run" position on the slider. I had flown alot of flights with my Sport Jet Hurricane all summer and never had a problem. On the second flight after switching to the new Radio, the Turbine shut down after a low pass and needless to say a had to land way down the runway and broke both wing panels during landing. The Turbine checked okay on the ground, but I did notice if i just touched the slider, not moved it, I would get the second beep for normal shutdown mode. I just installed the Pegasus in my new EuroSport and now i set the ATV on the second channel to 125% high and low and everything is checking out okay...
Old 06-04-2012, 07:07 PM
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Jack Diaz
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Default RE: Help diagnosing AMT flameout (pics)


ORIGINAL: Kevin_W
It is also possible to have an air bubble trapped in either the UAT or the filter that will remain stationary until the plane enters a different attitude, or some kind of vibration breaks it free. After a new install I always run the engine up to full power the shake the filter (or the whole airplane) vigorously to be sure there are no trapped bubbles left in the fuel system.
Dieselman: sorry. It hurts ! I think from the pics that it may be repairable.
Kevin: agree with you 100%

I would add a hint:
after a new install, or after the airplane has been sitting in your shop for a while:
- Fill the tanks.
- Disconnect the fuel line from the turbine, and connect it to the airplane fill line (one is 4mm and the other one is 6mm, so the 4 goes easily inside the 6)
- Using your ECU, run the pump at 3.5 volts for some 3 minutes at least, while doing the shaking and twisting that Kevin suggested.
- Watch for any air bubble circulating. You will be amazed to still see bubbles after a few minutes, when you put the airplane in different attitudes. (try to put it in every possible attitude).

In new installations, I also fuel and defuel a few times. If there is any debris in a tank (glue, kevlar, etc) you will hear the fill pump making a different sound when the debris clogs the clunk. Even if it doesn't clog the clunk, it will be deposited in the UAT outside the sock, where it doesn't hurt.


Old 06-04-2012, 07:39 PM
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Randy M.
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Default RE: Help diagnosing AMT flameout (pics)

Most likely there was still air in the uat. There is a process for the first use. You must get all the air out or you will flame out.
The process I use is- before installing it, I fill it thru the main line (backwards) with one of the barbed lines closed off, the other goes to a taxi tank or similar. I fill and shake and tap it on the table. Getting alot of the air out. Once I have some fuel in the taxi tank, I reverse the pump defueling the taxi tank while shaking and tapping again. I do this a few times until I know there are no air bubbles left. Then I leave it full and cap it off and install.
Should have no issues.
I've been running amt's for many years, I can count on one hand how many flameouts I've had.
sorry for your loss
Old 06-04-2012, 08:23 PM
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Dieselman1220
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Default RE: Help diagnosing AMT flameout (pics)


ORIGINAL: G4guy

Quick question, what radio are you using and on the Transmitter, what lever are you using to control the ECU?
Ron
Hi I have a Futaba 12fg the turbine switch is SA right next to my gear switch of SB i have them set in the same direction as gear retraction that way if I accidentally bump the turbine switch it will be upwards to the start/run position and I wont shut it down.

Thanks for all the ideas guys I didnt know about shaking the airplane while running the engine it makes sense. I also did not know about filling up the UAT first, I followed BVMs instructions but wasnt aware of the rest.
Thats what kinda sucks about where I am there is really no one to teach me these little tricks of the trade and it could have saved an airframe.

Jack- Im sure airframe could be repaired, but I do not have the skill level, time, nor talent to do it, so Im afraid i will have to scrap it, Or save it for parts If I can ever locate another one.
Old 06-04-2012, 08:49 PM
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Default RE: Help diagnosing AMT flameout (pics)

Yes sorry to hear that. I like to install the UAT with a service loop in the lines, where I can pull it out clear of the plane and run the turbine while beating the hell out of the UAT from all directions. In my experience with a new UAT I cycle the fuel in pump test mode for 5 minutes while hitting the tank every which way.
Old 06-05-2012, 04:35 AM
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Default RE: Help diagnosing AMT flameout (pics)

Sorry for the loss.


I've never had a n issue with my AMT, and I regularly run the tanks out of fuel. And to be very honist... my 180 almost doesnt' care if it gets a small air bubble. When one passes... you get a little burp, and a crackle in the sound... and it keeps running.

Also... for the guys asking about the second channel or hinting on radio issues... he wouldn't have gotten a low RPM shut-down. The ECU would either report a normal, or emergency shutdown.

As a third thought... it can't be a temp issue, because the early ECU's don't look at the temp probe after the engine has started normally. Well... it does... but it won't trigger a shutdown, even if you un-plug it. Basically, if it sees that it's running hot... it will cut the fuel to cool it, and if it's during an acceleration... it will slow the ramp.


With all that said... I'm going to say it's one of a few things.

1) The fuel pump is going bad. Are you monitoring your idle and full-throttle voltages after each flight? That's a sure fire way of knowing if you have a pump or fuel issue. (like a seal a leak, or plugged needles)

2) An RPM sensor that is going intermittent.

3) a rub in the engine. Look in the tail cone, and see if you can find any signs of the turbine wheel rubbing the NGV. If the peak RPM's are low (because of a rub) then the ECU will shut down the engine.


Just some random thoughts... take it for what it's worth.
Old 06-08-2012, 10:28 PM
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Dieselman1220
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Default RE: Help diagnosing AMT flameout (pics)

thanks for all the replys I like the idea of removing the fuel line to the turbine and running the pump while shaking the plane that seems like a sure way to work out any air bubbles. Also Ive been told that running a filter prior to the pump such as
the Festo inline filter does a good job of breaking down big air bubbles small enough for a turbine to swallow. Any truth to that? I was not running one which looking back now was very foolish of me as a run one in all my other jets. I just figured it
didnt have one before and never missed a beat. And good news a buddy of mine looked over the airfame and decided it could easily be repaired. So she will fly again!!
Old 06-09-2012, 03:06 AM
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Default RE: Help diagnosing AMT flameout (pics)

Good news for sure on the airframe !!!! I can tell you that you will get mixed responses on the onboard inline filter.. Some guys like them, some guys say filter from the can and run onboard.. I've done both. From my experience, AMT's can eat a lot of air bubbles and keep running compared to other engines.. don't ask me why... I mean if you get a 1/2 of air going through the line it will flame out, but I've seen just single bubbles spaced an inch or so apart go right through with a quick RPM loss and keep going. But as we know, we don't want any air,period. Sounds like you are on the right track.


Good luck, talk to ya soon !!,

Dan
Old 06-09-2012, 04:33 AM
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Default RE: Help diagnosing AMT flameout (pics)

ORIGINAL: Dieselman1220

thanks for all the replys I like the idea of removing the fuel line to the turbine and running the pump while shaking the plane that seems like a sure way to work out any air bubbles. Also Ive been told that running a filter prior to the pump such as
the Festo inline filter does a good job of breaking down big air bubbles small enough for a turbine to swallow. Any truth to that? I was not running one which looking back now was very foolish of me as a run one in all my other jets. I just figured it
didnt have one before and never missed a beat. And good news a buddy of mine looked over the airfame and decided it could easily be repaired. So she will fly again!!
To quote the BVM UAT instruction sheet: Additional Operating Tips
First start with an electric auto start:
"Fill the system through the UAT's third line. Then connect the filling fuel pump to the output tube of the UAT (The tube that goes to the engine fuel pump.) Run fuel through the UAT until no bubbles can be seen.

Be sure the 6mm tubing has a round, not oval cross section.

During the first engine run, set the throttle to about 1/2 power and shake the model observing that no bubbles exit the UAT. This might require a few minutes of running until the sack in the UAT is completely air free. Follow this procedure also if the system was completely drained for transit."


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