engine bolts coming loose

[John Jackson]

Hey All!
 I recently had a broken clutch that with less than 50 flights on it. I put it on the bench and noticed a possible culprit. It appears that the engine mounting bolts had backed out, one of the mounts were stripped so I replaced with new mounts. remaided without issue. after the second flight I noticed the engine bolts were loose again!!!! I'm using Blue lock tight,but they seem to keep backing out. any suggestions?

[Rodney Kirstine]

Are you cleaning the motor mounts and screws with something like denatured alcohol prior to adding the loctite?  Also,  are you giving it plenty of time to cure, too?

[John Jackson]

thank for the fast reply Rodney
cleaning all bolts and holes ...nitro is messy. what is proper curing time? is 12-14 hours adequate?

[Rodney Kirstine]

Yeah, that should be ok. There is also oil resistant loktite you could try.

[Tommy Wagner]

Mite want to also check the rear bearing is the motor running smooth?

[John Jackson]

I will check on the oil resistant product. engine runs smooth, rebuilt end of May. ys .56 fwiw.  I did not have any issues of this sort last season and flew the heck out of this heli. could you guys suggest a torque rating? I've never been a fan of the T.F.A.R. method

[flyalan]

Loktite 243 is the oil resistant thread locker. It is all I use these days.

Cheers
Alan

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[Kevin Feil]

Had this happen years ago, use the lock title Alan recommended and the cleaning/ prepping method Rodney mentioned. Put a flight on the motor and once finished flying , let the Heli sit 2-3 minutes after the flight and tighten the motor mount bolts again. Same principle you use when torquing an exhaust piper. Good luck!

K

[John Jackson]

thanks guys I'll provide an update

[Kevin Dalrymple]

243 is also the primer less loctite.

[Rodney Kirstine]

I've been using Loctite 248.  It's a medium strength thread locker that comes in a waxy stick form.  I like it because it's not as messy and I've been really happy with its holding power.

[cyprusflyer]

Vital bolts like these and feathering shaft especially, I always thoroughly degrease with acetone, it also gets most of the old locktite off. It is pretty volatile so evaporates quickly. Currently using Zap blue thread lock, have not lost a bolt yet.

[Kevin Feil]

Acetone will damn sure cut any residue. Make sure your in a ventilated area lol.

K

[Ross Lawton]

Hi John,

Good advice above, i do the same when building. I will have a cloth and a bottle of cleaning solvent like methylated spirits/acetone and will use it on the cloth to clean screws and components as i go. Make sure when using these types of cleaning solvents that you work in a well ventilated area.

Also check the use by date of your thread locking compound, i have seen a couple of instances where loctite has been out of date and the compound has not cured correctly.

When building i will use Loctite 243 (Medium/Blue) and Loctite 270 (High/Green) but will keep a bottle of the Zap Z42 (Blue) and Zap Z71 (Red) in my transmitter case with my tools.

Hope this helps,
Cheers,
Ross

[JASONBUCAO671]

get some pipe little pipe cleaners. most crafts/hobby shops have them. I dip the pipe cleaner in alcohol and run it thru the motor mount threads them self and let it dry.