Chris, I have no idea what you mold your landing gear out of...

[Kiba]

...but it has to be some of the most durable plastic out there.

I had an unexpected low altitude / low forward speed flameout yesterday and the resulting auto was pretty ugly. The heli was probably 100Y away and 15 feet off the deck when the flameout happened and because of the distance, alfalfa height, and irrigation checks in the field I misjudged the height of the ground, botched the auto and flared too high which popped the heli into the air about 4 feet which then dropped to the ground and bounced the heli into the dirt pretty good.

I couldn't see the heli at that point as it was hidden down in the alfalfa but with all the white smoke rising I expected broken landing gear, a broken tail fin, a bent boom & boom supports, and possibly a blade strike.

By the time I ran out there with the extinguisher in hand I was surprised to find a fully intact and upright heli with the turbine going through cooldown. The landing gear flexed enough there was some mud on the bottom edges of the frames and the bottom of the landing gear bows between the frames -- but nothing was broken. Plenty of mud stuck to the skids, tail fin, and bottom of the frames though.

I thoroughly checked everything and flew cautiously once more-- everything seemed OK. There was a bunch of air trapped in the fuel lines which caused the flameout, but I can't find where the air entered the system. While the main fuel tanks were somewhat low when the flameout happened the UAT was over 3/4 full of fuel when I picked the heli out of the mud. The fuel lines bewteen the UAT to the fuel pump suction side are sealed up nice and tight.

I'm going to do some more investigation and inspection today but in the event I don't find an obvious issue... do UATs go bad? It's always left full when I'm not flying the heli.

If I just hover the heli in front of me it will pull the main tanks completely dry and the turbine will run until the UAT has less than 1/4" of fuel left at the bottom and then it sucks air and flames out.

[cbergen]

Well I'm sure the soft ground helped keep it intact, but I appreciate the thought.

Check the fuel lines in the main tanks, that they haven't gone "hard" and aren't allowing the clunk to fall up when you invert....

Some have gone to using a loop of fuel line in the tank so the clunk is free to go where it needs.

It's possible the sock in the UAT has deteriorated, only one way to know for sure...

Chris B

[Kiba]

Don't sell yourself short on the landing gear Chris, it was a really ugly thud, bounce, and second thud. Oops.

I changed every tygon fuel line in the heli today and also replaced the UAT sock.

All of the tygon tubing including the clunk lines were a little firm and the cap on the UAT was barely finger tight. The UAT sock looked OK but since I was in there I replaced it.

Going to test fly tomorrow and see if that takes care of the problem.

Using an extra long clunk line is an interesting thought-- as of now I have it set up like the instructions with the clunks half-way into the length of the tank. It's always managed to nearly empty the main tanks before pulling air even flying aerobatics from take off to landing. Also, what you do you think of using seamless neoprene tubing for the clunk lines? Some say it's softer and more flexible than Tygon.

[cbergen]

As long as it won't kink, it should be fine.