Safety wiring worm clamps

[Bob Collins]

Well, here we are deep into the thread and we've talked about everything BUT safety wiring worm clamps.

The reason I'm asking is I'm installing a Reiff preheating system and the instructions state that the worm clamps holding the cylinder bands should be safety wired because they will work loose and break.

The system costs about $500 so I'd kind of like them not to do that.

[Mike Switzer]

Well, here we are deep into the thread and we've talked about everything BUT safety wiring worm clamps.

Worm clamps are not commonly safety wired.

The reason I'm asking is I'm installing a Reiff preheating system and the instructions state that the worm clamps holding the cylinder bands should be safety wired because they will work loose and break.

The system costs about $500 so I'd kind of like them not to do that.

If so why not ask them? I have seen a few Reiff systems installed on planes & I do not remember seeing safety wires. Maybe they have recently started recommending this, in which case they probably have a recommendation on the proper procedure.

[Auburntsts]

Well, here we are deep into the thread and we've talked about everything BUT safety wiring worm clamps.

The reason I'm asking is I'm installing a Reiff preheating system and the instructions state that the worm clamps holding the cylinder bands should be safety wired because they will work loose and break.

The system costs about $500 so I'd kind of like them not to do that.

Bob, did you go to the link that Marty put in post #3? I looked at it and the solution seemed reasonable to me.

[Reiff Preheat Systems]

Well, here we are deep into the thread and we've talked about everything BUT safety wiring worm clamps.

The reason I'm asking is I'm installing a Reiff preheating system and the instructions state that the worm clamps holding the cylinder bands should be safety wired because they will work loose and break.

The system costs about $500 so I'd kind of like them not to do that.

Actually our instructions do not say "they will work loose and break".

Per our Installation Instructions:

4. Safetywire the clamp screws to insure they will not vibrate loose. If they vibrate loose the heating elements will burn out. Put the wire in the screw slot and around and through the screw housing.

[mdawson]

Can someone point me to instructions on the proper safety wiring of worm clamps? There's nothing in AC43.13 that I can find.

Hi Bob

There are 2 quite different purposes in safety wiring worm clamps.

The first as the link in Marty's post shows is to safety wire the bolt so it doesn't come undone and the other is to capture the clamp in the event that it comes off either due to coming undone itself or shrinking of the material it is clamping.

So it depends on the purpose of your question.

As Marty has covered the first I'll do the second.

The main concen with the clamp coming adrift is it falling onto something that can cause damage. Perhaps because they have a background of engines being mounted in pusher configurations some Rotax people safety wire the clamps to stop them going through the prop. I know of no specific methodology as the clamps vary so much with the manufacturer but I basically just use common sense, for the clamp holding the aircleaner I find a hole in the clamp, usually through the screw mechanism somewhere which I can pass the wire through, or if there's a waist, just tightly wrapped around the screw housing and then run it back to the carb which has an ear for the aircleaner safety wire, twist up with minimum slack.

Hope this helps.

Mark