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Engines Plugs Mufflers Fuel > YS 91 SR Head Screws
 
 
dtrexel
Heliman
Location: Canyon Country, Ca.

I have a Vibe 90 with a YS91SR engine. Last weekend, my helicopter quit in the air and I had to auto-rotate it down. When I got home to look things over, I noticed that 3 of the 6 head screws came extremely loose.

I assume that was the problem because I was getting a lot more air in the engine and it created a lean situation which caused my engine to stop.

My question is if I should use loctite on the head screws and if I should use red or blue loctite?

Thank you,
Derik
09-17-2008 01:53 AM
 
 
bparro
Veteran
Location: indianapolis,in

dont use any locktite. Tighten the screws in a star pattern by hand and then run the engine. Shut the engine down and while it is hot tighten the screw again. Let the engine cool. They should stay put after this, mine have.

Miniature Aircraft USA, V-blades
09-17-2008 02:59 AM
 
 
PilotDaz
Veteran
Location: Seattle, WA

Good advice bparro, but I'd like to know how you re-tighten the head screws after a flight while they're still hot? You'd have to drop the entire engine to get it out of the fan shroud first?



I do use that approach on mufflers though.

~Team Collective Mayhem - "My anger management class really PISSES ME OFF!"
09-17-2008 03:13 AM
 
 
steffgiguere
Key Veteran
Location: St-Eustache, Quebec, Canada

Good point PilotDaz I'd like to know too. bparro is right though you don't use loctite on the the head because it get to hot and the loctite is useless in such heat.

I wish I could fly 24/7
09-17-2008 03:16 AM
 
 
Divot
Veteran
Location: Mesa, AZ

Quote 
Shut the engine down and while it is hot tighten the screw again. Let the engine cool

Quote 
Good advice bparro

I would disagree. Never torque head bolts while the engine is hot.
The heat on the head is uneven at this point. Tighten all the bolts to the same torque and when the engine cools there will be an uneven tension.

This is not rocket science. Just tighten the head bolts while the engine is cold. They will not come loose unless something else
is very wrong.
09-17-2008 04:03 AM
 
 
bparro
Veteran
Location: indianapolis,in

Hmm, well let me re-phrase, snug the bolts up but dont monkey fist tighten them!
The cooling shroud on my stratus is trimmed for the cooling head of an OS SZ so the head bolts on the YS are all easy to reach with a ball end wrench.

Miniature Aircraft USA, V-blades
09-17-2008 04:51 AM
 
 
Danish helifly
Heliman
Location: Denmark

tight the screws in a star maner when the engine is cold. Remember, metal will expand when it gets hot, and therfore you can not tighten the screws..
09-17-2008 09:00 AM
 
 
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Engines Plugs Mufflers Fuel > YS 91 SR Head Screws
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