Stationary Roll + Bad Clunk Line = You Know What!!!

[Rockohaulic]

OK, this happened on my EVO, but could just as well have happened with my Raptor 50, and I could use your vast experience...

Bottom line was I had just completed 7 fairly good (for a beginner) stationary rolls with my EVO 30. This is only the second time attempting them with a nitro. I came in to check fuel, header tank was full and main tank had about 1/4" left, so I went up for #8.

As Murphy would have it, I was about half way through the stationary roll, inverted, and the engine quit! Arrrrggghhhhhhh!!

It completed the roll fine, but then headspeed was gone. I hit throttle hold and attempted a landing. It hit level, on the skids, but HARD!

Broke the main frame and the servo frame (damn thin servo frame!). Very slightly bent the boom, and bent the flybar. That's about it. Landing gear fine, blades fine. I wish the landing gear would have given its life to protect the frame!!

By the way, has anyone ever noticed how thin the main frame is on these EVOs??? Too thin in my book.

Anyway, engine looked fine. Glow plug looked fine. Looks like the main clunk line was responsible.

So 3 questions:

1. How often do you replace the clunk lines?

2. What is a high quality clunk line, and where can I order it?

3. What else should I check/replace on a regular schedule to avoid mechanical failure?

Thanks guys!
Rockohaulic

[DebianDog]

1. Clunk lines "should" be replaced yearly if you fly a lot.

2. I use regular fuel tubing myself. Not sure that is the "right" thing to do.

3. Try and pull the ball links off Wear on any wires or pinched wires. Look for plastic dust (a sign of bad mesh)

[ClayK]

1. I check my fuel tubing about every 3 months. Quick pinch test and a visual inspection usually is sufficient. I just happened to pull my main fuel tank so I checked my main clunk. Good thing too, 6 month old helicopter and clunk line was squishy.

2. Regular fuel tubing for me, as long as it's still flexs.

3. General PM (preventative maintenance) Schedule for me...

Pre-flight:
Ball links, not too tight, not too loose.
Servo wheel screws, present and tight.
Control rods, present and functioning.
Tail belt/boom, not too tight, not too loose.
Fasteners/screws (this is more or less a visual inspection)

Monthly:
Triflow main shaft and tail output shaft, too much oil attracts dirt.
Check for dirt and crap here too, you may have to clean before you lube.

3 months (or after crash):
Everything above
Fuel tubing
Fasteners/screws, physically check tightness.
Servo/radio check.

That's about all I got. You should check bearings, especially if you get jitter, but I wouldn't just go cracking the mechanics open to check bearings as that may introduce a fault that wouldn't have previously existed.

Depends on fault isolation/symptom resolution too. For example, my engine was making an awful noise. Fan was loose and the piston rod scratched back plate on the engine. That service had me pulling engine, replacing bearings, pulling starter shaft, replacing those bearings, replace backplate, install starter shaft, install engine, clutch alignment, check all fuel lines, replace main tank (had a pin hole leak) and service inner portion of frame (clean it out). I like that sort of thing, so when I find something deep inside the mechanics and it's all apart, just do all the logical stuff that should come to mind. :dontknow