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Safety Wire Screw Clamps

Caummisar

Caummisar

Well Known Member
While looking at a builder's website, I notice he/she had safety wired SS screw clamp screws. Is that standard practice? If yes, then why didn't I know? :confused:
Rq761v


https://www.flickr.com/gp/188428474@N06/Rq761v
 
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Way back in the beginning I did. I haven't found the need since. I'm not sure who I thought I was going to impress :). Oh, I guess there was that OSH judging thing.
 
Perhaps an airline A&P?

If memory serves me correctly for the older airframes, this was standard practice on P3, FA18 and A320 pneumatic systems, although those clamps were a completely different heavy duty type design.

If I still had access to airbusworld I'd have a quick look at the AMM to confirm.

I've kept that up on our RV9A / O-320, validated by finding multiple loose clamps on initial receipt of the aircraft.

Whatever gives you confidence to fly over long stretches of water, and it's a safe practice regardless.

(Coming from the airline world I was gobsmacked to see what is and isn't safetied. It's like working on tractors)

Pat.
 
I've wondered about the need -- couple of thoughts:

Not all clamps are created equal. Note the difference in the shape of the slots cut in the band -- genuine Breeze Aero-seal clamps are "D" shaped which matches the profile of the screw much better than other clone clamps.

see https://www.aircraftspruce.com/catalog/appages/qs100h.php and https://www.aircraftspruce.com/catalog/appages/15-06060.php for comparison.

Most fasteners that should be wired have a hole drilled in the head or shank ("Put wire here...") -- running the wire over the slot seems to be a solution looking for a problem.

So, unless you really like safety wire, poking/scratching yourself - I'd leave it off.

Just my opinion - I'm not an expert.

B
 
Years ago my buddy had one vibrate loose on the exhaust heat muff on the Cozy MKIV. We found it during a condition inspection. If it had come fully off, it would have gone right through the prop, so I safety wired most of the worm clamps on the RV-10 "just in case". Not sure I will bother on the 9A.
 
I had a hose clamp on the Vetterman exhaust system come loose on our RV-6, so I safety wired it. I’d never seen a worm-drive hose clamp with safety wire on it before, but it stayed tight. I suppose it came loose because it ran so hot and then cooled back to room temp over and over. I’ve since redesigned that connexion with a different clamp, so no more problems. But I’ve never had a problem with the ones on the Lycoming intake tubes.
 
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If you are doing a thorough check FWF every time you change the oil, I don?t see the need for safety wire on clamps.

I include checking clamps as part of my regular maintenance at every oil change, which I do at 25 hours. Nothing fancy, I just put a screwdriver or nut driver on them and snug them up if they need it.

My only exception is the clamp the secures my purge valve cable to the bracket. I have safety wire on that clamp. In this case the wire acts as a backup to the clamp itself.
 
For any important area, it just takes 30 seconds to do and guarantees that it won't come loose. In the past, I had the clamps loosen the hold the leg fairings on my main gear. Every couple flights they needed snugging up. Since the safety wire trick - the have been tight at every annual.

No brainer.
 
When I was a mechanic in the military we had lots of them safetied. So I just did the same on my RV-8..
 
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