Ollie Bloor

Hi

I have had roughly 16 flight with my kangeroo now and have started to have problems.The model starts fine i fly around for about 6 mins and the engine shuts down followed by a fuel trail[X(].When i land and have a look the fuel tank is just above half,This happend the same every time ANY IDEAS ??????[:-]

P.s There is no air in the UAT


Cheers Ollie Bloor

bvmjethead

My Feedback: (10)

NOT trying to be a smart alec.............................

But did you follow the directions that come with the UAT for the initial filling and purging of all the air?

If not you WILL have these kinds of problems.

Ollie Bloor

Hi

Yeah i did this when i first had the UAT and have had many flights previous to my problem,anymore ideas HELP!!!![:'(][&o]

CFII1974

My Feedback: (5)

Do you have a filter between the tank and UAT? If so you may want to take a look at that.

Vincent

My Feedback: (61)

do not drain the uat after your flying session, it is best kept full for the next time.
V..

Ollie Bloor

No i do not drain the UAT after flying but i do store the model on its nose,also i have no filters in the system itself
Is it crucial where the fuel pump is in the system?????????

Ollie Bloor

Also the motor always shuts down the same time each time,and the fuel tank is always just above half Any ideas?????????lso the motor aslways shuts down the same time each time,and the fuel tank is always just above half Any ideas?????????

Ollie Bloor

PLEASE HELP!!

jetflyer

My Feedback: (5)

Have you checked your main tanks to make sure there are no problems? Also, you might try running it on the ground for the 6 minutes and have a look at the fuel system and see if anything is abnormal.

How do you have the UAT mounted in the airframe - Vertical or Horizontal?

JR Gautreaux

Shok

My Feedback: (28)

how did you guys purge your UAT?

When I first filled mine, I just kinda shook it around then squeezed fuel out the line a few times. That seemed to do the trick because my motor fired right up and has never had a burp since.

Was there something else I was supposed to do as well?

Ollie Bloor

My UAT is placed horizontal in the model.It took about severn runs to get all the air out of my UAT by shaking it side to side and up and down being careful not to stop the engine.I also have checked all the fuel system making sure the clunk is on etc and cant find anything

patf

My Feedback: (4)

have you taken the uat out of the system and tried to run it? sounds like your problem might be upstream... clogged vent, some other "bind" in the system... are your tanks collapsing? etc. 6 minutes sounds like enough time for that problem to become enough that the pump cannot overcome it.

Ollie Bloor

I also did run the model on the ground and experienced no problems i also fired the engine up after it had stopped and had no problems?? However when the model does shut down the is a fuel trail,and the handset just says flame out???????

Ollie Bloor

Ok yeah ill try taking the UAT out of the system but i have checked the system totally and found no blockages any other ideas

Ollie Bloor

But could it not be the UAT and could it be the position of the pump, its between the uat and the motor but closer to the motor than the UAT any ideas

weasel33

Remount the uat either vertical or at a slight angle say 80 degrees
repurge the system and run it on the ground watching for any air bubbles going from the pump to the turbine
if so check all connectors in the fuel system on the suction side.
if you screw the top off the uat i have known them to suck air
festo connectors only work under pressure not designed to work under suction (if you use them)
if know air seen then and it shuts down then check out the pump

goodluck

Brian

Woketman

My Feedback: (6)

In my experience, a flame out with a smoke trail immediately after, normally means that there was an air bubble big enough to let the flames of combustion extinguish in the combustion chamber. The rest of the engine is still plenty hot enough to vaporize Jet A, and so, upon resumption of a steady fuel stream after the bubble has past, you get the smoke trail (vaporized Jet A). What ever the cause of the bubble, it sounds like it is definitely a bubble causing the shut down, not simply fuel starvation due to a blockage (not to say that some starvation issue could not somehow cause the bubble's creation, such as cavitation perhaps?).

RC_MAN

My Feedback: (11)

Check the pickup line in the main tank feeding the UAT. Is it at least 1 inch from the back? Any chance of it binding? Also you may have a pinhole inside the tank line. Once the fuel drops below half the hole gets exposed and induces air into the fuel system.

Good luck

Peter

Ian R

Hi Ollie

I agree with Woketman, I think you have an air leak somewhere, odd it happens at the same time.

Mounting the UAT at an angle is good practice although does not sound like the cause.

A few questions 1. What turbine
2 what are the main tank/s and what are the tank stoppers
3 is the vent pipe the same size and fuel to turbine side of the tank feed
4 Check the pipes to the festo fittings are still round and clean cut with a sharp knife. In particular the UAT to turbine side of the UAT. Air leaks before the UAT would show in the UAT I would think.

ps one last question is your farther Rob ? If yes pass on my best regards

Ian R

Global10

My Feedback: (20)

I would replace the fuel lines if its not that much trouble.

Woketman

My Feedback: (6)

Also, remember that the Festo fittings that we use were really intended for positive pressure applications (a greater pressure INSIDE the tube than outside). Before the pump, we always have a negative pressure situation and we have a positive pressure situation AFTER the pump. In my experience, in the negative pressure case, Festos can leak a lot easier. A worn Festo, a tube cut sloppily, a too tight radius bend adjacent to a Festo (ask me how I know that one!). Something to check when scouting for leaks.

BlueBus320

My Feedback: (57)

Hey Olly, dont think you mentioned if the UAT was still full when the engine quits ?....My buddy lost a bandit turning base to final, totally dirty when the engine quit & he tip stalled. He was useing some machiene screw to plug the fill line instead of the airtight plug BV uses. But basically the Jetcat ran like a million bucks for about 5-6 minutes until the UAT ran empty due to the leak.
Jay

RCpropo

My Feedback: (1)

Ollie,

You said the fail came at 1/2 fuel tank. Try to test your turbine with 1/2 tank since the beginning. If fail continue the problem is inside the main tank; maybe a pinhole on the rubber tubing.

Good Luck,
Ricardo.

Doug Cronkhite

My Feedback: (34)

Your clunk might have come off in the main tank leaving you only the fuel draw down to the tank caps.

Vampire

My Feedback: (2)

Ollie Bloor

I believe I have a possible answer to this condition.

The EXACT same condition hit my FACET-2300 last year at Heart of Ohio.

The Facet had been flown without incidence many times then all of a sudden, 2 back to back in-flight engine shutdowns at nearly the same time into the flight.[:@]

Fortunately the FACET has a great glide ratio and I put back on the runway both times without incident.

I proceeded to dismanteled the entire fuel system looking for the problem and could not find anything obvious. I then was mentioning this condition to a fella from SWB who manufactures the UAT's and he asked me what vintage UAT I had. I told him it was nearly a season and a half old. He then proceeded to inform me that they had issues with the CAPS LEAKING AIR and their fix was to place several wraps of Teflon tape around the threads.

The unfortunate thing about this conversation was TIMIMG. I had just purachsed a NEW UAT from BVM and installed it thinking that perhaps the mebrane was fowled.[]

The "tell-tail" observation of a leaking (air) UAT is that after landing your aircraft, you will observe that the UAT is EMPTY despite having suffecent fuel reamining in your tanks !!!!

The reason you see a smoke trail is most likely when an engine shutdown occures WITHOUT a command from the ECU, the fuel pump will continue to run, thus the trail.

I replaced the old UAT with the new one and all was fine (BTW, the new one had teflon taped threads !) I have since taped the OLD UAT and it is working fine.

Hope this helps answer your question.

Best Regards: