Safety wire, proper safety wire technique for using safety wire on ultralights, and ultralight aircraft.

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Safety wire where and how to use it on ultralight, experimental aircraft and amateur built aircraft.

In ultralight aviation there are three things that I have learned you can't be without. Velcro, duct tape, and SAFETY WIRE. This article is about the latter, Safety Wire.safetywire.jpg (93989 bytes)

I have had a couple of rolls of the stuff around here for years. It comes in several different thickness, for different applications. It is cheap, very light, corrosion resistant, strong, and easy to install. 

I first ran into "aircraft safety wire" at Sun N Fun in 1980, I bought 3 different spools - .020/.032/.041 and I still have all of them sitting in the top of the tool box next to the installation pliers. Back then they cost me about $5 bucks a roll - last year I was pricing them and they now cost about $9. each. But 1 roll will do the average guy a lifetime!  

.020 is very thin, not very strong, but you can bend it around just about anything. You use it to safety wire light bolts or fittings where you need to bend the wire around a lot of corners, and where the wire does not have a lot of pull on it.

.041 is extremely strong,  because it is twice as thick and is very stiff, and difficult to work with. It doesn't  bend easily and won't tighten around tight  radius, you use it on wide radius turns where high strength requires the extra effort to use it. 

.032 is what I use the most - and ran out of first!  If I was shopping for a spool of safety wire this would be what I would recommend. It  is easier to work with, and reasonably  strong  and should work on anything you might need to use safety wire on an ultralight.

While there are different materials used to make safety wire, brass an aluminum, I don't recommend them. The type I recommend is 302/304 soft temper stainless spliers.jpg (53586 bytes)teel.

One of the things I quickly learned especially with the thicker wires is that a safety wire tool makes the job a lot faster and easier. Tpliers2.jpg (32095 bytes)here are several different tools ranging from a unit that looks like a screw driver, to a wire winder tool, to a safety pliers. For a klutz like me these make a beautiful finished job, with the right tightness and strength.

They are easy to use. I have the pliers type shown at right. You wrap the safety wire around whatever it is you are securing, bring both ends back into the pliers mouth, close the mouth down on the wires, lock it (it has a little spring loaded locking mechanism) then pull a round knob in the middle of the handle back - a lot like those spinning tops we use to get as a kid. You know the ones that you pumped up and down and the top would spin for what seemed like hours! Am I dating myself here? Anyways when you pull on the knob the plier handles turn and the wire wraps around itself.

Areas where you might use safety wire include around bolt heads, or nuts where there is not means of locking them. Areas of special concern are prop bolts, control system linkages, areas of movement, or vibration. Another area of use is on turnbuckles to prevent them from backing off in flight. 

Several years ago I forgot to safety wire the turn buckle on the cable operating the elevator on my L'il Buzzard. About three hours into a cross country flight I noticed that the stick movement was very sloppy and loose. A check of the cable revealed the turn buckle had backed off 3/4's of the threads in just 3 hours. 

Other areas that I use safety wire are:

-As hose clamps around the fuel lines, fuel pump, carb, primer bulb. Using the pliers it is easy to use the .032 wire. I wrap it around the hose two or three times then bring it back to the pliers. Presto you have a clamp that is cheap, effective, and easy to remove.

-As replacements for the older style EGT probe clamps. I have been doing this for years, after the one of the clamps broke off and went through my prop. You wrap two or three wraps around the probe, place the probe into the hole in the manifold, (you may have to use a couple of washers to space the probe out so it does not touch the other side of the manifold) then wrap each end of the safety wire around the exhaust manifold a couple of times - then bring the two wires together and hook them into your pliers, and pull. (.040)

-On the 53/582 you won't find a clamp small enough to go around the vent on the top of the cylinder head (water pump outlet on inverted engines) two or three wraps of safety wire does the trick. (.032)

-On the exhaust springs. Run a piece of safety wire through the center of the spring, onto the spring hook then back through the center to the other spring hook, use your pliers to tighten. THEN fill the spring FULL of silicone.

-On the rotary valve tank cap. If you look you will see that the cap has a little hole in it at the bottom of the threads. Hook a piece of safety wire though it and then secure it to the little tab on the rotary valve tank. That's what it's there forSafety Wire

-To secure your airfilters to your carbs. If you check out the alert bulletins on site, and the accident statistics you will find a number of instances where the airfilters have come off and gone through the prop. 

-Secure spark plug caps to spark plugs, especially in inverted engine installations like the Challenger.

-Secure the carb nuts and studs on the 185 Rotax engine used on the Lazair ultralight. They had a tendency to vibrate out, so we would drill a hole in the stud and nut then safety wire it back onto the carb to stop them from turning.

Of course the main area that you will find safety wire used in on prop bolts. In fact it was the first thing that a conventional pilot pointed out to me on my Challenger, the bolts in the prop hub weren't secured and could vibrate and back out. This  results in a loose fitting prop which shears the prop bolts!

On my old Buccaneer I replaced the little rings on the rudder control pins with safety wire when one of them came off in flight after I taxied through some mud and weeds.

A bolt that is properly safety wired like that on the right just doesn't just hold the fastener in place, it serves to pull it tighter. Each bolt holds the other and actually tightens the other if it starts to come loose.

How to Properly Install Safety Wire

There are a couple of basic rules to follow when safety wiring something. 

They are:

-If you are safety wiring a nut or bolt FIRST torque the nut or bolt to its proper torque. Where possible align the holes that are going to be used to safety wire the units in place. BUT DON'T OVER TORQUE or UNDER TORQUE them to achieve this!

-After installation the safety wire should be tight! So as not to allow the unit(s) to move.

-Safety wire should always be installed so as to make the nut or bolt "TIGHTEN" itself when the safety wire has been installed. That is the safety wire should come around the top of head of the bolt/nut and back onto the securing unit so that the safety wire PULL is in a tightening direction!

-NEVER over stress the safety wire. This weakens it, which could cause it to break under vibration or load. This is generally caused when you "over wind" the safety wire. Safety wire should never be nicked, or kinked. 

When cutting the safety wire always leave 4 to 6 turns after the loop. REMEMBER always bring the safety wire AROUND the head of the bolt/nut in a tightening direction, in as small a contour to the bolt/nut as you can get.

A Klutz's guide to using a set of safety wire pliers!

After you have wrapped the safety wire around the object, grip both ends of the wire in the jaws of the safety wire pliers and slide the outer sleeve down with your thumb to lock the handles. 

Now grasp the knob located in the middle of the pliers and gently pull out. This will cause the plier handles to turn, twisting the safety wire! 

When you have the amount of twists required, grasp the handles and squeeze. This will release the safety wire from the jaws of the pliers.

Use the cutters in the jaws to cut the safety wire to the proper length, then bend the end of the wires over so that you don't poke yourself on them the next time you reach into work on something. 

Securing the rotary valve tank cap on a 532/582 Rotax engine.
Find the hole in the cap, it is at the bottom of the threads in the cap. Run a piece of safety wire through it, and pull it back out so you have about 6 inches of safety wire. 

Move down to about an inch from the pliers end of the safety wire. Hook the pliers up to the safety wire and twist until you have a nice spiral coming up to the pliers. Install you cap onto the rotary valve tank. 

Now wrap the safety wire around the tank - in a tightening direction and connect it to the little standoff on the rotary valve tank. Hook one end of the wire through the standoff, grab both wires with the safety wire pliers and twist gently. You don't want to have too many loops incase you have to take the cap off.

Here are some examples of proper safety wire techniques.

These units are used where a nut or bolt does not have a hole for safety wire. You install them under the nut/bolt bend the tabs over the side of the nut/bolt and then safety wire the tab with the hole in it.

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