Did You Do That Safety Wiring?


There are certain questions that you just naturally don’t want to hear. For example, “Is this the last beer?” or “Do you know how fast you were going?” or a variation on that, “Didn’t you hear me tell you not to cross that runway?”

I’ve heard the second question in that list more times than I can count, most recently last week. My answers never seem to rise to the level of creativity that would cause the officer to fold the ticket book and say, “That was so good, I’m gonna let you slide.” But last week—busted for 33 in a 25—the pandemic saved me. The officer mentioned something about COVID-based slack and I got a warning instead.

The question I detest the most, however, is this: “Did you do this safety wiring?” There is no percentage in lying because this is what’s known in both the legal and aircraft mechanic trade as a leading question. The interrogator is fully aware of the answer and is only awaiting the victim’s reply to key gales of laughter. It’s even worse if there’s no laughter but just a wry smile that telegraphs that the wearer hasn’t seen safetying this bad in 45 years of swinging wrenches but is too polite to mention it.

My safety wiring isn’t always that bad, but sometimes it causes even me to pause in wondrous appreciation of the heights to which human ineptitude can soar when propelled by the tug of a shiny knurled knob. Safety wiring isn’t that hard. Good safety wiring is a dark art that makes performing a heart transplant seem like making a cheese sandwich. I’ve done enough re-dos on the same set of bolts to make me wonder if it would be better to just unspool 10 pounds of wire and crumple it up on the floor before even starting in the hopes that the first try would click.

My last safety wire work was on the Stromberg carburetor in the Cub. Pulling the thread backward, the reason I had to do that was because I had disassembled the carburetor. And the reason I did that was because I entered the hangar the day before to find a sizable puddle of gas under the airplane, dripping from the bottom of the carburetor. Now if you know anything about Strombergs, you know that they have like three parts—you could make one out a beer can and a couple of nails in about two hours. You’ll need a pair of shears and a drill for the metering jet, but you could probably use one of the nails for that.

Anyway, if gas is leaking out the bottom, the only thing it could be is either a stuck or gas-logged float or something in the float valve seat, right? “Right,” says my IA friend Dan. So I’ll just take the carb off and look-see. This is easy except for ^%$ bastard nut at the back of the carb that takes five times as long to remove as it did to overhaul the engine. When the last screw was removed and I opened the float chamber—nothing. The float was perfect and nothing was in the valve seat except … the valve seat.

What the actual ^%$)? Inspecting the now carburetorless engine, I notice it’s still dripping gas. What the actual ^%$)? It’s coming from the primer line, which enters the intake manifold above the carburetor. Jiggling the plunger causes it to stop. These things happen with 82-year-old airplanes, but I have to admit, I’d never seen that one. Nine hours later, I got the float chamber screws safetied in such a way as to not constitute a Class A felony and the ^%$ bastard nut was re-secured.

The lesson for you here should be obvious. Gas leak? Jiggle the primer and go have a smoke—outside the hangar, of course—and come back. If you don’t smoke, start. If the leak stops, you have benefited from my quiet, but confident incompetence.

You’re welcome.

I learned another interesting thing that day not related to old airplanes but the current social condition. At the end of one of the hangar sections are bathrooms, one for men and one for women. Things being as they are these days, if the men’s is occupied, I just use the women’s. (So sue me.) I was shocked to learn it’s painted pink. Pink! The men’s side is blue. I was further surprised to learn that while the men’s side has both GoJo and regular liquid soap, the women’s side has just the soap.

Is this a budget thing or a suggestion that women don’t get their hands greasy working on airplanes? While you contemplate that, I have a big box of aborted safety wire to carry to the scrap bin. Two pick-up loads should do it.

Other AVwebflash Articles


  1. Paul are you sure you’ve not been looking over my shoulder at every 25 hour oil change? Reinstalling and safetying the oil screen on the back end of my C90 costs me more in safety wire than the oil itself. By the way I think a Marvel carb is the easiest solution to leaking carburetors on old small Continentals. And, for what it’s worth, the restrooms at my hangar complex are unisex as in the great outdoors does not provide a separate men’s and women’s.

    • PS: and by the way, old Mr Broom from early ’70s Spartan A+P carburetors class would flunk me today for my safety wiring.

  2. I have become a big fan of AgentJayZ on YouTube, who is a jet engine repair and restore expert in Canada. If you want a tutorial of the arcane intricacies of safety wiring, check out his channel. I now know more about safety wiring, and why I’d probably never want to attempt it, by watching his videos. I also have a great appreciation for how jet engines work.

  3. In Paul’s hangar section I certainly hope that the women’s bathroom is to the right of the men’s.
    You do know that women are always right !

  4. Several years ago when I bought my airplane, my then mechanic told me that if I was going to do any work on the plane I needed to get a pair of safety wire pliers. So, when the Snap-On tool guy came around the mechanic led me to his van and asked for a pair. How much are they? I asked. That much? Wow. “Oh, but they are bi-directional”, Snap-On guy replied. Bi-directional, hmm. Well, I guess that is worth it, so I paid the man. The problem is that now, not only do I have to remember which way to wind the wire around the bold head, I also have to decide which direction to twist the wire. Too bad someone has not invented a pair of pliers that automatically knows which way to turn and how many turns are needed for a “proper” safety wiring job. In the meantime, I try to console myself by placing all my reject attempts in the recycle bin. I hate to see all that nice stainless steel go to waste.

  5. I worked with a retired Army helicopter mechanic and crew chief to get my experience needed to get my A+P. He showed me the “Army” way to safety wire without using safety wire pliers. Of course I still use pliers to safety wire. Want something challenging to safety, try safety wiring a control cable turnbuckle after adjusting rigging. That can be lots of fun!

  6. Seven turns per inch. Put the pliers where you want to stop the twist. Did not know that until now.

  7. Ok, just jiggling the 82 year-old Primer doesn’t fix the problem. Jiggling is barely even a band-aid. Doesn’t sound like your IA taught you anything of value. That primer needs to come out and be rebuilt. Rubber o-rings do not last 82 years. This situation will only get worse and it will likely rear it’s ugly head in-flight. DON’T take a chance on having an in-flight emergency for $2 worth of o-ring’s! Am I being harsh? I don’t think so. After 32 years in this industry, I have watched the competency levels of maintainers go right in the toilet. So am I blaming you? No. But if your IA can’t help you identify a simple (and common) issue like a leaky primer and ACTUALLY FIX IT, Then I think there is a bigger issue that needs to be addressed than sub-par safety wire!!!

    • It doesn’t have O-rings. It’s a Lunkenheimer, long since out of production. The fix is Teflon strong found in the plumbing aisle at TrueValue or so the Cub gurus say.

  8. After 62 years of flying Stromberg…aka…Strombone equipped aircraft, I finally, finally had one that didn’t leak! I always, always shut the fuel off in my Strombone Aeroncas, etc because if I didn’t, the floor would then be coated with fuel next trip out. I’ve know aviators that made it a life’s work to get the the metal tipped needle and metal seat to mate perfectly and not let fuel leak by. Then, I bought a used engine for my last Aeronca 2 years ago, and it came with a Stromberg carb attached. And….it DID NOT LEAK! I recently sold the Aeronca. But before that, I would wander around the airport mumbling ,”Mine doesn’t leak. Mine doesn’t leak”. Any visitor to the hanger would hear those words first thing. I did notice occasionally a person then glancing down around the zipper on my jeans.

    • Ours leaks too, but only around the float chamber gasket. It doesn’t leak–weep, really–enough to run out on the floor.

  9. Sure, I’ll add my two cents!

    Once had a phantom leak from an old Marvel carburetor. You are right that it’s almost certainly a float or needle valve. If it’s the float, the unit is coming off. If it is the needle valve there is a chance that a speck of debris has lodged between the needle and seat. A solid wack with a plastic hammer “repaired” my leak never to return. P.S. It’s a shame there isn’t a hall of fame dedicated to botched safety wiring – I could fill a 55 gallon drum with mine.

  10. Safety wire takes practice. This my two cents on it. When I first started as A&P I used duck bill pliers and they worked fine. I got some “Okey, Dokey approved Safety Wire pliers” at a pawn shop. I used them but really didn’t like them. I found that different pliers nick the wire and it breaks easy. I was told there was different ones for different thickness of wire. I wound up drilling the twister lock off and using them by hand.
    It allows me to get a better feel for the tightness of the wire. I also lightly smoothed the jaw teeth so they didn’t nick the wire. One trick I learned working helicopters when you need to get a cotter key out of a hole and can’t get to it. Take about 2-4 feet of wire loop it thought the key loop of the head, double back and Wrap both wires across the handles of the pliers a couple times with 2 feet of slack. snap it hard a couple times and the cotter key will pop out. I use the pliers tip to install, remove and bend them too. This works if they are not really big. I have several pairs the I use in machine shop to pull keys out of grooves, or what ever I need a long handle pliers for. I use the whip effect when pulling wire through a tight turn too.
    I safety a lot of stuff on shop projects if I have problems keeping bolts or whatever tight.
    People always would ask who did my safety wire and comment on how nice it looks. I have done lots of safety wire on people planes for free. The main tips I found improves you safety wire tightness and looks is I always twist the wire in the direction that puts the wire down on the side of the bolt head where the wire comes around. As the twist get there or the end next to the nut or bolt head I do a “Barrel Roll” with my wrist and it pulls the wire tight and sucks it right in to wire hole. I do some over as I usually break the wire due to nicks or just a little too tight, but no buckets full. My pliers are only one way twist and that’s one reason I got to doing them by hand. You can get it start through the bolt head and twist is by hand until you at the other end, then tighten up with pliers, pull through hole and finish with barrel roll at end. PLEASE, PLEASE, FOLD THE TAILS BACK IN SO THEY DON’T RIP THE NEXT GUY REACHING IN THERE. I HAVE MANY ARM SCARS FORM PEOPLE NOT FOLDING THE TAILS BACK IN.

    It took over twenty years to use a complete can of wire myself. Have many “Borrowed” from tool box that never made it back. They just don’t have that homing sense to come back.

    • My A&P showed me that “barrel roll” maneuver, too, only he calls it “elliptical”. A rose by any other name… but yours makes more sense. Until then, I couldn’t figure out how to get the safety wire to look tight at both ends.

      I like the idea of grinding off the ‘teeth’ of safety wire pliers so it doesn’t knick the wire. I’ll be doing that next.

      PS – in addition to folding the pig tails, please, everyone, PLEASE – cut tie-wraps flush, and parallel! Don’t cut across the end, or at an angle! It’s about as painful as trying to hang a curtain on a barbed wire fence in the dark.

  11. It’s in the A&P/IA code of ethics not to teach pilots how to do safety wire. If we teach you guys the intricate secrets of this arcane art, not only would we lose our superiority, but you folks would be taking the money right out of our pockets.

    And go with the simple things first, Paul! Rebuilding a carb when you just have a primer leak?

    Love all of your articles, so glad for one that just had me giggling for hours!

  12. After my last annual, where I “helped” by doing, several times over, a bunch of lock wiring on a numerous air fittings we had to change, I was asked if I was going to participate in the local blood drive.

    No I replied, I gave at the hangar……