Watch out for this issue with Fuel Compession lock

[bradh1963]

Had a very interesting situation yesterday. I started my Raptor 50 (OS 50 Hyper) and must of got a fuel compression lock. The clutch / fan nut came loose and the whole assembly span upwards a few threads. Anyway, i took it apart and put it all back together, i couldnt see any damage so i made a special tool off the Raptor Technique web site and tighten it all back together with locktight. What i hadnt realised is the upwards force of the clutch shaft has actually damaged the two bearings very badly to the point you could hear them rumbling over the engine noise. Moral of the story, avoid fuel compression lock at all costs. Lesson learned.
Anyone else ever had this problem??

[Badger50]

Yep, same thing happened to me, in fact 3 times on the same heli. O.S 50Hyp, metal fan, etc. I blue lock tited the hell out of the thing everytime. Same thing happened. So I used red locktite. Needless to say, it worked. Bad news is, I'll probably never get the fan off ever again. Oh well, gives me a good excuse to give my wife when I need a new engine. :lol:

[Phillips942]

Hey BRAD which two bearings were damaged??? You never said which ones.
I (3) have had that problem 3 times in a row on my new Hyper 50. I put it all together and took it to the field... Turned it over with my starter the first time and i got nothing (forgot my ignitor) so I try it a second time and yep HydroLock and i hear something im not supposed to hear when i turn the engine over. My Clutch Fan unscrewed itself... so i knew right away i was done for the day. I didn't ruin any bearings (i don't think) but i haven't had the problem since then either.

[helicraze]

You can remove red loctite almost as easy as the blue, it just requires heat.

[Badger50]

Cool. Thanks for the tip.

[jgunpilot]

The problem is, it takes an acetaline torch unitl the nut glows a dull red.

[FlyingHigh 450]

Good advice guys :thumbup:.Sorry that this happend to your helis :( but im new to nitro helis and have my first rappy 30 on its way.Im going to pull the clutch assy off it as soon as I get it and loctite it.What type should I use and what else should I thread lock?

[rotorhead58d]

Good advice guys :thumbup:.Sorry that this happend to your helis :( but im new to nitro helis and have my first rappy 30 on its way.Im going to pull the clutch assy off it as soon as I get it and loctite it.What type should I use and what else should I thread lock?

use blue locktite on ALL metal to metal screws

[awr]

The problem is, it takes an acetaline torch unitl the nut glows a dull red.

I had the same problem on my Raptor 50 - both with the OS .50 Hyper and the OS .46.

My fan nut came loose three times - the last time I used red locktite and it never came off again.

Don't use a torch or any other type of open flame - it's not necessary.

All you need to remove the nut is a soldiering iron. I know this because I had to take the fan off of the
.46 to put on the Hyper. I've since taken the fan off the hyper as well.

I use the "stylus/pencil" type of soldiering iron (same iron that Finless uses in his videos) with the removable tips.

Take the tip off and put the hot end of the soldiering iron barrel on the crankshaft bolt, making contact with the bolt and the fan nut at the same time and hold it there for between 30 seconds and a minute. The soldiering iron I use is 45 watts, so if the one you have is less than that, you may have to apply the iron for up to two minutes - use your own judgement.

For good measure, I heat up the end of the crankshaft as well so that the heat travels all the way through the bolt to any threads you might have missed. Putting it on the end of the crackshaft as well also increases heat transfer.

Once the thread lock heats up it becomes at least as pliable as dry blue thread lock, if not more.

If you want proof, take an ordinary bolt and lock-tite a nut on the bolt using red lock-tite - heck, put three of them on so you can see how far the heat travesl.

Put as much on as you want because I want you to be sure of the theory. Let it set at least 24 hours and then try to take it off using the method I described.

Wayne

[FlyingHigh 450]

Take the tip off and put the hot end of the soldiering iron barrel on the crankshaft bolt, making contact with the bolt and the fan nut at the same time and hold it there for between 30 seconds and a minute. The soldiering iron I use is 45 watts, so if the one you have is less than that, you may have to apply the iron for up to two minutes - use your own judgement.
Wayne

I'll have to remember this,Thank you sir :thumbup:.

[WayneBrown]

The problem is, it takes an acetaline torch unitl the nut glows a dull red.
no it doesn't, anything approaching 250* will free the locktite up.

[bradh1963]

Hi Philips942

sorry for the delay in replying. the two bearings that were trashed were the bearing directly above the clutch assembly. I was able to change them without taking the chopper entirely apart. I bought the bearings from the local bearing shop for $12aus