Adil Nasim

My Feedback: (61)

Hi,

I had a couple of weird problems on my normally perfectly running P-80. It seems like the turbine would go through the normal start process and then give me a green light but after a few seconds on idle will shut down. It did it once and I checked for bubbles etc. but nothing. I flew it twice after that without any problems of any kind but after taxing it back the last flight and before getting a chance to do an auto shut down it stopped again. I plugged in the GSU and it showed an error of low idle. At shut down it had an low rpm of 22K and an EGT of 340. Any ideas? The para meters are set at 117K high and 37K low. Had plenty of fuel and no bubbles when it shut down. Maybe I need to call in to go over the other parameters?

Thanks - Adil

mr_matt

My Feedback: (10)

Was not sure if you had already talked to JetCAT USA yet or not.

What you are describing is a flame out. It is most likely caused by air in the lines, or a restriction in the fuel system that the system cannot compensate for at idle before shutting off.

I suggest running a very large standard clunk (not pleated or filtered), triple check all connections and run a UAT. Make sure you do not have a kink in the feed line out of the UAT near the nipple, you can get small bubbles there sometime. Make sure the fuel filter in the plane is oriented vertically, sometime bubbles can build up int he filter if it is mounted horizontally.

Check you filters as well.

Good luck

Adil Nasim

My Feedback: (61)

I had actually already called JetCat and Bob had pretty much the same suggestions and advice as you. I will make the neccessary changes and let you know if the problem still exists.

Thanks - Adil

sky warrior

Hi Adil
I have a 120 but have not had the same problem However after many good runs and absolutely no problems it cut when down to the level of the centre of one supply tank. Why because the clunk had come off..why because I used the larger bore Tygon tube 6.5mm o.d not 6mmm o.d. and it had expanded enough to come off even with safety wire!!
Just maybe check your tube size and tight fit connections as it maybe unable to cover the air bleed (so to speak) on an oversize tube joint .. You never know it may help you and be your problem too.

Bye

Adil Nasim

My Feedback: (61)

Hi Matt and SkyWarrior,

Thanks for all the tips and suggestions. My clunk was OK but I think the problem had to do with the filter being horizontal vs the suggested/preferred method that is being vertical. I for some reason had never added a UAT and finally installed it. Last couple of weeks, I had absolutely zero problems. So much so that I won the Best Turbine Award with my set up at the Brooklyn Jet Rally

I have been checking ever since and the maximum amount of air bubbles (not visible) makes the air bubble inside my UAT grow from a dime size to a nickel size after 10 minutes of flying. That is nothing!

Thanks again!

Adil

mr_matt

My Feedback: (10)

Glad to hear you guys are having some success.

The JetCATs run good, so now most problems will be isolated to the fuel system.

Here's a tip that I have not previously mentioned. A good habit to get into is to look at your max pump voltage after shutdown (assuming you went to full throttle at some point during the flight). It is in the min/max menu.

Now the first question is, what should the voltage be?? Unfortunately, it is hard to give a value as each turbine is a little different, and even the installations will cause a difference in pressure. Try to establish a "baseline" value yourself, that is with a clean filter, clean UAT, good fresh clean kero, etc.

After many flights, you will perhaps see the value start to slowly increase from flight to flight, maybe as little as .01 to .05 volts a flight increase. This is an indication that your fuel filter is slowly clogging. After it has raised about .2 to .4 volts higher than your standard clean system baseline, you want to clean the filter.

A final note, I learned the value of removing the vent plug before flight (unless your are practicing deadsticks or testing your pacemaker)

sky warrior

Adil
Glad to hear your problems are solved.
Just for the record I made a mistake on the pipe dia it is 6mm and 5mm not 6.5/6 as in my origonal post. Just in case someone else reads this and goes down the wrong tube .... so to speak !

Bye

Adil Nasim

My Feedback: (61)

Hi Matt,

I have never forgotten the vent plug but have done one thing which I WILL NEVER DO AGAIN.

After one flight, I was charging the ECU battery but instead of having the model on a stand, I just reached in through the gear opening and attached the charge lead (gets disconnected from the ECU via Sermos connectors). Upon finishing the charge, I reached under the plane and connected the connectors back. Started, normal taxi- As soon as I rotated and went full vertical, I hit the retract switch and poof!! If you have not guessed it - I accidentally wrapped the battery cable around the LG strut since I was reaching and not looking!!

I did manage to recover the plane from full vertical and land down wind with some minor L/G damage but did learn my lesson!

Thought I'd share.

bcovish

My Feedback: (8)

Matt
At idle, voltage is .69
Max voltage 2.80. Someone told me 2.80 is to high. Filter is clean. What's your opinion?
P80 / Bob Cat

mr_matt

My Feedback: (10)

Hello,

2.8 is on the high side for a P-80, but not outside the bounds for a clean filter. 2.5 to 2.7 is more normal.

Remember to get a baseline and compare readings. Has the voltage been going up on you?

THe filter is not the only area you can get restriction. THe filter type clunks can clog, and so can a UAT!

bcovish

My Feedback: (8)

Thanks for the reply

There is only about 10 flights on this engine including the UAT. When someone told me 2.8 was high, I cleaned the filter and it is still at 2.8 No lines are kinked. Engine runs fantastic. I'll keep an eye on voltages. Also, not using filter type clunks.

mr_matt

My Feedback: (10)

Hello again,

Nope you are good to go, just check the voltage after each flight.

HAve fun!

bcovish

My Feedback: (8)

Thanks Matt.

Am having fun and am going to have more fun this Saturday. I don't know when I'm going to get this Bob Cat painted. Flying in primer. Winter project I guess. Going to FIJR Nov 1.

Happy Bob Cat/Jet Cat owner