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May 7, 2009 - Continue twisting counterclockwise beyond the bolt to form a pigtail. ... Leave about 1/4 inch of a tail (about 3 twists) Tuck it around the last ...... wire is also made from copper for use on emergency levers and switch covers.
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More Than You'll Ever Need to Know About Safety Wiring By Chris Densmore Safety wire is used to secure fasteners to prevent them from coming lose. It's used a lot in aviation and racing. To safety wire fasteners you will need safety wire, safety wire pliers, wire cutters (dykes), and needle nose pliers. In a pinch, you can make do with the wire and needle-nose pliers with a cutting edge. The hardest part of safety wiring is drilling the holes in the hardened fasteners. There are jigs available to hold nuts and bolts so they can be drilled more easily. You may also be able to purchase pre-drilled fasteners and save yourself some time. Safety wire comes in many types and sizes. You must first select the correct type and size of wire for the job. Annealed corrosion-resistant steel or stainless steel wire are used in race preparation.

The following general rules apply to safety wiring: 1. All safety wires must be tight after installation, but not under so much tension that normal handling or vibration will break the wire. 2. The wire must be applied so that all pull exerted by the wire tends to tighten the nut. 3. Twists should be tight and even, and the wire between nuts as taut as possible without overtwisting. Safety wire pliers can easily twist the wire too far, breaking or weakening it. 4. For this reason, wire between nuts should be twisted with the hands. The use of pliers may damage the wire. Pliers should be used only for final end twist before cutting excess wire.

Patterns All critical nuts except the self-locking types must be safetied; the method used depends upon the particular installation. The illustration at left shows various methods commonly used in safety wiring nuts, bolts, and screws. Examples 1, 2, and 7 show the proper method of safety wiring bolts, screws, square head plugs, and similar parts when wired in pairs. Examples 4 and 5 show a single threaded component wired to a housing or lug. Example 3 shows several components wired in series. Example 6 shows the proper method of wiring castellated nuts and studs. Note that there is no loop around the nut. Example 8 shows several components in a closely spaced, closed geometrical pattern, using the singlewire method.

Single Wire Safetying Insert the wire through each part consecutively in the direction that will prevent the part from loosening. Draw the wire tightly around each bend and twist the ends into a tight pigtail close to one of the safetied parts. Cut the pigtail square, leaving a minimum of three twists. Bend the pigtail over against the part being safetied to prevent snagging. You should not use safety wire longer than 24 inches for single wiring three or more parts as a group. Double Wire Safety Wiring By Hand Pull the wire through the first bolt. Bend one end of the wire around the head of bolt #1 toward bolt #2, in a direction such that a pull on the twisted wire toward bolt #2 would cause bolt #1 to tighten. Twist the outer wire under the other wire close to bolt #1. Continue twisting the wire clockwise,keeping the strands wide apart to ensure a tight even twist. When the twisted pair reaches bolt #2 without slack, insert the wire in the the bolt hole in a direction so that bolt #2 cannot loosen without pulling bolt #1 tight. Bend the free wire around the head of bolt #2, and twist the wires counterclockwise. Continue twisting counterclockwise beyond the bolt to form a pigtail. Cut the pigtail square, leaving a minimum of three twists. Bend the pigtail over against the part being safetied, to prevent snagging.

Double Wire Safety Wiring Using Pliers Start by looping the wire through the fastener, using a little extra wire, because you don't want to be

short at the end. Loop the wire coming out of the bottom hole around the bolt head clockwise and pull the wire tight with needle nose pliers in the direction of the second bolt. Start the twist by hand (two to three turns) then bring the two wires together and clip the safety wire pliers on the wires next to the hole it will go in on the second bolt, keep the two wires next to each other in the pliers jaws (no gap between them). Pull the safety wire pliers twist-knob to twist the wire, hold the pliers to keep it from twisting backwards and let the knob retract, then repeat until the desired twist is reached. Do not over-twist the wire, you can easily weaken or break it. Unclip the safety wire pliers, put one wire through the second bolt (using needle nose pliers helps), loop the other wire around the bolt head, start the twist by hand, clip on the safety wire pliers and twist. Now you're ready to cut the wire. Leave about 1/4 inch of a tail (about 3 twists) Tuck it around the last fastener so it doesn't snag.

Assorted Odd Bolt Heads and Nuts When various types of bolt heads and or nuts are safetied to stationary parts, you can use either right or left hand twists. Attach the safety wire in such a manner that if the bolt or nut should start to loosen then the wire would be in the direction of tightening the fastener.

Alternatives Nyloc nuts are a good alternative, when applicable. The thing to remember is the nylon insert wears out after repeated use, and will not hold. Technically, they should only be used once. Also available are special washers as show. Torque the nut over these washers, bend the tabs up along the sides of the nut, and safety wire the perforated tab to something secure. Probably best to use these once, too. Putting Holes in Your Nuts This need not be as painful as it sounds. You just need a drill with a very sharp bit, a vise to hold your nuts, a center punch, and a steady hand. Secure your nut, use the punch to mark where you want to drill, and carefully drill the nut. You'll want to lubricate the bit, to prevent overheating and premature failure. I've used DeWalt's 1/16" Cobalt bits with Lithium grease quite successfully. Bits aren't expensive, so you'll want to pick up

Click to view larger image.

two or three because they're very brittle, and break easily when bent. Apply light pressure, and coat the bit's cutting edge in grease occasionally. Be patient, and take your time. Ideally, the bit should not get hot. If it does, it's probably dull and should be replaced.

Suppliers of safety wire, pliers, and related items. You Favorite Scooter Racing Shop Progressive Suspension Lockhart Phillips USA Do you know how to tune a scooter? Want to author an article about a particular tip or technique? Space is available to interested persons who wish to contribute information or a short article, in compliance with rules issued in the introduction.

While looking through the toolbox I stumbled across a few things that I picked up along the way to safety wire. Since I really did not have a need to do any... it has just sat there, mocking me. One thing I would like to do on my new "project" is safety wire just about anything that can/should be done. So... I know some of you have alot of experience in this area, especially the aircraft folks, so what are the tips/tricks to do it like a pro? I had found this site that seems to give some pointers but what has experience taught others is what I am curious about... http://www.whizwheels.com/Tips/safetywiring.html

That is a pretty good link that explains the basics. The source manual is the Navair 1-1A-8 tech manual, but it covers all aircraft structural hardware selection and use. The chapter on safety wiring is about 20 pages though. Here are a few pointers that aren't on that link: 1) Chose the appropriate safety wire. Most structural hardware that isn't subjected to extreme vibration use .032" wire. This will cover about 95% of your safety wiring needs. We use .020" for electrical connectors

High vibration areas (gun systems and certain larger engine components) get .041". 2) smaller wire sizes get twisted a little tighter than the larger sizes, but 8-10 twists per inch works pretty well for all. 3) twist the wire all the way to the next hole, with just enough twists so that if you added one more twist, the last twist would hit the hole (i.e. as close as possible without touching). 4) the pigtail should be 1/2" long and folded back on itself so it doesn't jab you the next time you work in that area. 5) the safety wire must always pull in a tightening direction. It should be pulling at an angle, so that if you pulled on the safety wire it would tighten the fastener. No neutral safety wire (neither tightens or loosens). 6) Do not untwist the wire if you twist it too far or twisted it too tight. Cut it off and start over. 7) Generally you safety wire from the object you are securing to a fixed point (the pig tail is at the fixed point, not on the bolt head). There are exceptions due to inaccessibility.

Here is an example of an incorrect safety wire job.

In this pic, the D (the wire that wraps around the bolt head) is on the wrong side. The wire should be pulling the D in a tightening direction. This pic would be correct if it was a left hand threaded bolt It looks like someone did this by hand and not with wire twisters because the twists are counter clockwise while the pliers should twist clockwise. Both strands of wire should be twisted around each other and not one strand wrapped around the other. The pliers will do that for you automatically. Now come the tricky part, the direction you twist the wire does have an impact on how you safetywire a bolt with one hole straight through it. If the person had used a clockwise twist, the D would have had a tendency to pop off the bolt head. If it had been on the right side to begin with, then a clockwise twist would have helped hold the D in place and keep it from popping off the bolt head. And last, the pigtail should be folded in half so it doesn't poke somebody. This is better, but is a little ameturish:

The one on the left is pretty good (notice how the 'D's pull on the tightening side of the bolt and the twists but right up to the holes in the bolt heads? The problems with it, is someone obviously untwisted the wire (the kinked part on the bolt head). The other two are sloppy, there is too much space between the first twist and the bolt head. This could have been fixed by throwing in one manual twist with the pliers--just twist the pliers in a clockwise rotation-- like you were turning a crank, and it will put a twist up tight against the bolt Also the twists don't run right up to the holes in the bolts. The bottom one is neutral at head best Here is good example of what safety wire should look like:

Single strand safety wire is a good method two, but it should only be used were fastener are no more two inches apart, and they have to form a circle (or any shape as long as the first and last fasteners are no more than 2" apart)

If you can't get enough of this stuff, the Wiki is pretty decent too. http://en.wikipedia.org/wiki/Safety_wire

When I first saw this thread I thought that I should post this, but only just today found their page (such as it is). As routine I've carried my safety wire & pliers in my Chase tool kit for ~20 years. I've been carrying this tool for about a year, but a friend bought one nearly 5 years ago and swears by it. They offer several different models, but unfortunately their index link is dead. They're frequently found at Left Coast Gun Shows, which is where I bought mine. Clamptool.com

Works much, much better at any sort of clamping type limp-home repair than does the normal safety wire pliers. I think of this tool and some wire as a "hose clamp in a can."

Posted: Thu May 07, 2009 9:16 am

Post subject:

examples _________________

Safety wire From Wikipedia, the free encyclopedia

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Safety wiring of two pairs of drilled-head bolts This article includes a list of references or external links, but its sources remain unclear because it lacks inline citations. Please improve this article by introducing more precise citations where appropriate. (February 2008) This article may require cleanup to meet Wikipedia's quality standards. Please improve this article if you can. (February 2008) Safety wire or lockwire is common in the aircraft and racing industries as an extra precaution to keep vital fasteners from unintentionally loosening and parts from falling off due to vibration or other forces. This function is often referred to as positive locking. It also allows rapid and easy visual inspection of fasteners to ensure that they have been tightened. Safety Wiring of fasteners is often a requirement to pass technical safety inspections in racing. Safety wire itself is available in multiple gauges and different materials, depending on the application. In consumer aircraft and racing applications, stainless steel wire is used, most commonly in .032" diameter, although other gauges are used for specific circumstances. Typically, safety wire is threaded through a hole drilled into a fastener or part, then twisted and anchored to a second fastener or part, then twisted again, usually with the aid of safety wire pliers.

Contents [hide] ·

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1 Application o 1.1 Principle o 1.2 Installation o 1.3 Removal o 1.4 Proper techniques 2 Tools & accessories o 2.1 Safety wire

2.2 Safety wire pliers 2.3 Safety wire twisters 2.4 Safety wire tabs 2.5 Pre-drilled fasteners 2.6 Drilling jigs 3 Safety 4 Proprietary methods 5 Other methods of fastener retention 6 Advantages vs. disadvantages of traditional safety wire 7 See also 8 References 9 External links o o o o o

· · · · · · ·

[edit] Application [edit] Principle There are a few techniques for different applications. Non-proprietary safety wire systems all work on the same principle, which is that the tension of the wire on the fastener prevents it from working itself loose due to vibration or other forces. The wire itself maintains tension and remains in place by being twisted around itself and attached to the fastener to be secured on one end and an anchor point (which could be another fastener) on the other end. Since safety wire is made of a malleable alloy, it retains its shape after being bent, rather than springing back to its original shape. This property allows it to remain locked around an object, such as when it is passed through a small hole on a fastener, looped back upon itself, and then twisted. The same process is then repeated around the anchor point, which could be another fastener. Since it remains twisted instead of unraveling, it acts as a fixed loop and will not back out without considerable force (greater than the stresses which it is intended to counter) being applied.

[edit] Installation Safety wire installation is a fairly simple task, but needs to be done properly to ensure proper security for the fastener in question. First, a length of wire is cut off of a spool. The length of the piece of wire to be used is determined by the distance from the location of the fastener to be secured to another fixed location, which will act as an anchoring point for the safety wire. The wire should be cut to a length that is slightly longer than twice that distance. The next step is to take the removable fastener, such as a bolt, drill a hole through a part of it that will be accessible even when it is fastened (such as the head of the bolt), fasten it in the desired location, and then thread one end of the safety wire through the hole and pull it back upon itself, such that the two ends of the wire are now equal in length and form a loop through the fastener. The wire is then grabbed a short distance before the loose ends (with enough wire left so that it can be secured around the anchor point) with the tool of choice and pulled taut. Using safety wire pliers or the twisting tool of choice (simple pliers can be used effectively, if not efficiently), the wire is twisted to the optimal number of twists per inch. The wire is then released from the tool, with the two loose ends remaining adjacent to each other. One of those ends is then threaded through a hole on the anchor point, and pulled through and brought together with the other loose end, such that a loop is formed around the anchor object and the

wire between the anchor object and the original fastener is twisted and barely taut. With the two loose ends now on the opposite side of the anchor point (with one end going through the anchor and one going around it), the twisting process is repeated on the loose ends. When finished, the loose end is cut off with a pair of diagonal cutters or wire cutters (many safety wire pliers have a wire cutting feature), such that enough twists are left to prevent the wire from unraveling. The remaining end can have a sharp edge from being cut, so technicians will often bend it down against another hard surface to prevent it from damaging other components, such as electrical wiring insulation, or from causing injury to future technicians working in the area.[citation needed]

[edit] Removal Safety wire is removable, and removal is necessary to remove a fastener that has been safety wired. Safety wire is removed by simply cutting it, untwisting it, and unthreading it from the secured fastener and the anchor point. It can also be cut off very close to the fastener and anchor points so it can be removed without unthreading. Cut safety wire has sharp ends and users should be careful to not injure themselves or damage delicate components that are nearby. Special attention should be paid when cutting safety wire to where loose pieces land, especially in racing applications where lost pieces are commonly responsible for punctured tires. Any scraps from installation or removal should be disposed of properly. Although malleable, safety wire cannot repeatedly be deformed without breaking. Therefore, once used, safety wire should not be reused as it will be weaker than when first installed.

[edit] Proper techniques When using the most common gauge of safety wire, which is .032, the optimal number of twists per inch is 7 to 9. When using .041 or .040, optimal performance is achieved by twisting the wire 5 to 7 times per inch. On the smallest wire .020, 8 to 10 twists per inch is optimal.[citation needed] Equally important are the direction that safety wire is lead from the fastener to be secured and the choice of anchor point. The safety wire should be threaded through the object fastener such that it creates tension in the opposite direction of the fastener's removal. For example, if a standard automotive bolt in the U.S. is being secured, then the safety wire when installed should put tension on the bolt in a clockwise direction, since that is the direction that the bolt turns to tighten.[1] When securing a single fastener, the anchor point for the safety wire should be a fixed point on the object. The fixed point should be something that will itself not move, and that will not be able to release the anchor end of the safety wire under normal conditions. It should also be free and clear of any moving parts that could damage the safety wire.[2] When securing two or more fasteners, acceptable technique includes securing them against each other. In such a scenario, the safety wire is run through the first fastener (creating tension in the direction of tightness for that fastener), twisted, and then run through the second and subsequent fasteners such that the fasteners create tension, through the safety wire, in the direction of tightening for each fastener. When implementing such a scheme, the location of

the threading holes, length, tautness, and proper twisting (both the number of twists per inch as well as the direction of twist, which should alternate between fasteners between left-hand and right-hand twists) of the safety wire are all crucial in order to properly secure the fasteners. [3] When drilling a fastener, the choice of where to drill it depends on the type of fastener and to what it will be wired. Some fasteners are best drilled through two sides of the head near each other, where as others are best drilled through one side and the top, and yet others are best drilled through two sides that are opposite each other. The choice of where to drill a particular fastener depends both on where the fastener can tolerate being drilled while maintaining physical integrity and from what direction the securing force via the wire will be applied.[citation needed] The alternative to drilling holes in fasteners is to use safety wire tabs (see Safety Wire Tabs section below), or to purchase pre-drilled fasteners.

[edit] Tools & accessories

A one-pound spool of 0.020 stainless steel safety wire.

[edit] Safety wire Safety wire is commonly .020, .025, .032 or .041 inches in diameter, but .021 and .051 are also available, and usually made of stainless steel, but is also available in monel and inconel alloys for high temperature applications and copper for break-away applications.[4] For consumer applications, it is typically sold in 1 pound spools enclosed in a small cardboard or plastic canister.

[edit] Safety wire pliers Safety wire pliers come in three common sizes: 6, 9, or 12 inch(also called 7, 10, 13 inch, respectively, for manufacturers who choose to include the knob at the end of the pliers, which is used to actuate the twisting of the pliers, in the measurement). Safety wire pliers work as follows: The technician grabs the two loose ends of the wire to be twisted in the end of the pliers; he then locks the handles of the pliers closed, which secures the loosed wire ends in the jaws; he then grabs the knob at the end the pliers, releases the main body of the pliers, and pulls back on the knob which causes the pliers to twist. The wire then twists. When the wire has been twisted sufficiently, the technician holds the pliers, releases the knob, and squeezes the handles of the pliers to release the locking mechanism, which loosens the jaws, thereby releasing the twisted wires. He then proceeds to the next fastener in the series or uses the plier's built-in wire cutters to trim off the excess wires. The final step is the push down the

sharp end of the secured safety wire to eliminate any hazard from the sharp edge left from the excess being cut off. In addition to built-in wire cutters, some safety wire pliers feature an angled or diagonal tip to their jaws which allows easier grabbing of wire. The angled tip is also useful for pushing down the sharp clipped end of the secured safety wire. Some models have a feature that catches the excess wire that is cut off. This consists of a pair of rubber pillows located in the depression aft of the cutting blades. Safety wire pliers also vary in the direction of their rotation when the twisting knob is pulled, with some pliers rotating clockwise, some rotating counter-clockwise (often called RightHand Twist and Left-Hand or Reversing Twist), and yet others have a selector function to allow the user to twist the wire in either direction without switching tools. The pliers can also be purchased with the option of the twisting knob returning to its position automatically or manually.

The "pignose" safety wire twister.

[edit] Safety wire twisters A safety wire twister is a simple tool that allows the user to grip the two loose ends of a piece of safety wire and then, while holding the main barrel of the tool, turn the end that is not gripping the wire (which is bent to create a simple cranking mechanism) in order to twist the safety wire.

There is another type of basic safety wire twister which is similar to a standard screwdriver, except that the tip has a small grasping mechanism to hold the ends of the wire while the technician turns the handle to twist the wire. The advantage to this tool is its long and thin design, which can access hard-to-reach areas where one's hands or pliers do not fit. It is commonly referred to as a "pignose" due to its snout-like appearance.

[edit] Safety wire tabs Safety wire tabs are washers that are used to secure fasteners by transferring the force of the safety wire to the head of the fastener to be secured. The are installed just like any other washer, after which the sides of the tab are bent up to make contact with the sides of the head of the fastener. One side of the tab is longer than the other with a small hole at the top, through which safety wire is threaded. Once the Safety Wire is properly installed, the sides of

the tab transfer the force of the safety wire to the fastener, as though the fastener itself had been drilled and had the safety wire run though it. The advantage of safety wire tabs is that the fastener to be secured does not need to be drilled, which can be advantageous for fasteners that should not or cannot be drilled because of size or damage concerns. They can also be useful when a fastener needs to be replaced, the replacement is not already drilled, and circumstances do not afford the time or tools to properly prepare the replacement fastener. The disadvantages are that it adds extra distance between the head of the fastener and the surface to which it is to be secured, and it is not as secure as securing the wire directly to the fastener itself as the tab could be a point of failure if it somehow unbends or the hole breaks (which is more likely than the hole in a drilled fastener failing due to the thinness and malleability of the material from which it is made).

[edit] Pre-drilled fasteners For certain applications where safety wiring is common, fasteners come pre-drilled with holes to accept safety wire. When wiring something that did not come with pre-drilled fasteners stock, however, the more cost effective way (as opposed to replacing all stock fasteners with pre-drilled ones of the same type) is often to drill the stock fasteners.

[edit] Drilling jigs Because the use of twisted safety wire to secure fasteners requires the fasteners to be drilled, tool makers offer jigs to help technicians drill the fasteners to be secured. Although pre-drilled fasteners can be obtained, most fasteners to be secured start out never having been intended to be secured (e.g., a production motorcycle which was built for the street but which has been converted in to a race-bike). Such fasteners need to be drilled. Drilling them is often difficult as, due to their small size and irregular shape, securing them properly and applying a drill effectively can be trying. As a result, technicians often break drill bits or damage the fastener when the bit slides off position. A useful tool is a drill press, because it allows the technician to apply the force of the drill bit directly to the fastener being drilled and eliminates lateral movement; but even with a press the fastener needs to be secured to prevent it from sliding out from beneath the bit. Even though drill presses ease the process, a press isn't always available, such as at a race event; and even with a press, the problem of securing the fastener still exists. To solve those problems, jigs are available which are designed to securely hold the fastener and provide a guide-channel for a drill bit (with either a hand drill or a press) so that the technician can easily and directly apply force from the drill to the fastener without having it slip off or breaking the bit.

[edit] Safety Safety wire has sharp ends after being cut. It should therefore be disposed of properly when being scrapped. Technicians should also wear eye protection when cutting safety wire (particularly thick twisted ends) as the cut off ends tend to fly out from the cutter. Technicians should also take care not to cut their hands on the sharp ends, or to damage any sensitive components (e.g. electrical wires or assemblies) that are near the work area.

[edit] Proprietary methods

Safety cable is an alternative to safety wire. Safety cable is defined as a group of strands righthand helically twisted without a core. This eliminates the need for twisting during installation, as is required with safety wire. Several companies manufacture safety cable, and it is becoming an industry standard due to easier control of critical inputs and reduced installation time. Installation and quality requirements of safety cable are governed by SAE AS4536[5]. One safety cable manufacturer Daniels Manufacturing Corporation of Orlando, Florida. Daniels manufactures a product called Safe-T-Cable, which they advertise as, "The complete fastener retention system."[6] The Daniels system works by providing pre-cut lengths of safety wire that have a large cap on one end. The cable is threaded through a hole on the fastener to be secured, which is large enough to accommodate the wire but too small for the cap on the other end of the cable to pass through it. After the other end of the wire is passed through the anchor point, the technician takes an extra end cap and the special tool that is available from Daniels and crimps the cap on to that end of the wire. Again, the end cap is too large to pass through the hole that the wire passed through, and thus the cable is secured.

[edit] Other methods of fastener retention There are also other systems of fastener retention that do not rely on safety wire at all, such as Nord-Lock's system of counter-locking washers,[7] safety pins, etc., all of which accomplish the same objective as safety wire, which is to prevent vibration or other forces from causing the undesired loosening of a mechanical fastener.

[edit] Advantages vs. disadvantages of traditional safety wire Although many systems purport to be more efficient than installing traditional safety wire, an advantageous by-product of the twisting method of installing safety wire is that it leaves a highly visible and easily inspectable indication that the fasteners in question are in fact properly secured. In addition, safety wire twisting is a standard, non-proprietary technique, and tools and materials can be easily found, cheaply purchased, and mixed with other brands while still working properly (provided of course that all components are used properly and with the proper types of complimentary components and tools, if not brands). The primary disadvantage of traditional safety wire is the time it requires to install properly when securing fasteners, although technicians who use it often can implement it fairly quickly. It also leaves behind waste products when ends are clipped off or when it is cut off of secured fasteners that need to be removed during maintenance, resulting in sharp metal bits that can easily damage soft materials or injure skin. However, the amount of waste product is relatively small, it is non-toxic, and the hazard can be mitigated altogether if technicians properly dispose of any waste product. When clipping off ends, the ends can go flying off which makes their recovery difficult and can cause injury to anyone in the immediate vicinity, such as the technician or an assistant; however, this can also be easily mitigated by using extra care or by using safety wire pliers that have a special insert that is designed to catch clipped off ends. Another disadvantage is that since the manual skill required to implement traditional

safety wire is easily learned, the techniques required to maximize the retentive force of safety wire (e.g., in which direction the retentive force should be exerted, the direction of twist, proper angles for securing multiple fasteners, proper twists per inch, which type of wire to use, etc) are often ignored by non-formally trained technicians (e.g., hobbyists) who use safety wire for their projects.

[edit] See also ·

Cotter pin

[edit] References 1. 2. 3. 4. 5. 6. 7.

^ SAE AS 567 ^ SAE AS 567 ^ SAE AS 567 ^ SAE AS 567 ^ SAE AS4536 ^ Daniels Manufacturing Corporation ^ Nord-Lock - Products

[edit] External links · · · · ·

(Racing Example) (Aircraft Example) (Auto Example with Movie) (Safety Wire and Pliers) (Guitar Repair and Manufacturing)

Retrieved from "http://en.wikipedia.org/wiki/Safety_wire"

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. 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 steel. 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. There 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 for -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.

Aviation Maintenance Safety Methods

General

The process of securing all of the nuts, bolts, screws and fastners on an aircraft is known as safetying. The proper use and method of safetying helps ensure that the aircraft hardware does not become loose from vibration forces. It is necessary that you become familiar with the various methods and means to secure this hardware. Depending on the part or hardware, used in a given installation, will determine the method of safetying those parts to ensure their security. The most common methods of safetying items is through the use of cotter pins, safety wire, self-locking nuts and special fastners, lock washers, snap rings and safety clips.

Safety Wire

The utilization of safety wire is the most positive and accepted method of securing hardwarewhich cannot be secured by any other method. Safety wire is used to secure two or more hardware pieces in such a way that any tendency of one of the pieces to lossen will have a reciprical effect (of tightening) on the other piece of hardware. The most common sizes of safety wire are .020, .032, .040 inch diameter. The wire is made from extruded stainless steel which provides adequate strength and workability and is compatible with a wide variety of materials from a corrosive standpoint. Safety wire is also made from copper for use on emergency levers and switch covers. This method secures the control from inadvertant activation and yet allows the operator to break the safety when the employment is needed. Copper safety wire should be replaced periodically because the copper may work harden or age harden over time. Another spacialty type of safety wire is made from alumel and is found in aircraft with turbine engine installations and is sometimes used as the resistance wire for the engine tempurature indicating system. Aluminum and zinc plated steel wire should not be used in aviation applications. Safety wire techniques vary depending on the item being secured, however, what does not change is the direction of pull. All safeties with safety wire are tied in such a way so as to pull the hardware in a tighening direction. To see the various acceptable methods of employing safety wire, please refer to publication AC43.13-1.

The two most common methods of employing safety wire is through either the single wrap or double wrap method. The single wrap method when used on bolst or screws is simply feeding one end of the wire through the hole or holes in the hardware and continuing the process all the way around the component, ensuring a positive direction of pull between adjacent fastners. The safety is completed by securing the two ends by double wrapping, cutting off the excess wire and bending the end in (to protect people from injury). The double wrap method is a method of twisting the wire, esstantially braiding the wire, to sceure two or more components. Cut a length of wire of the appropriate size and pass through one of the holes in the hardware or component till you reach the approximate mid-point of the wire. Pay attention to the direction of pull for the fastners so you can stratagize how the wire be routed between the two points. With our wire at the mid point, we will have a left and right hand length of wire in front of us. Put a slight amount of tension on the wire so that it is not slack and cross the left over the right at approximately a 45 degree angle. Congratulations- you just completed one twist. Continue the process of crossing left over right until you reach the hole on the adjacent fastner or component. Pass the nearest wire through the hole and then apply tension, as you did before, and hold. Apply tension to the opposite length, which we will say is now in our left hand, and pass around the perimeter of the fastner head to where the two ends meet at the outlet of the hole. Now this time cross right over left to secure the two lengths. If doing a safety in pairs we can secure, cut annd secure the end of the wire, if we have a three-way safety just continue right over left to the next point- pass the wire through and around and then switch back to left over right to scure the tail (pigtail) of the wire. The alternating method of twisting the wire helps secure the wire closely to the hardware so there is little or no slock in the wire. If the wire is too slack it can pop over the head of the fastner and will not be effective in securing your hardware. Note: The brief description just given is for hardware with right hand threads. Oil caps, valves, draincocks, electrical connectors can all be secured using the double wrap method of security. Turnbuckels can and must be secured either with safety wire or clips. If using safety wire please refer to AC 43.13-1 for reference and very clear pictures of how to secure turnbuckles with their various end fittings. Safetying turnbuckles is not difficult but will take some practice, if you would rather slide in a couple of clips they are part number NAS 651. One more point on turnbuckles and then we will move on. There is some very specific guidelines the FAA anad most other aviation regulatory agencies have established for safetying control cables, be sure to use the proper data when selecting the appropriate size diameter and material type of safety wire before you start. Here are some general guidelines when installing or inspecting safety wire installation.

a. A pigtail of three to six twists or 1/4 to 1/2 inch should be made to secure the end of the wiring. The pigtail must be bent back or under to prevent it from becoming a snag or injuring yourself or someone else. b. Safety wire can never be reused. When cut off a new piece must be put in its place. c. It is not acceptable to unwrap a safety and attempt to wrap in the opposite direction. If the wrap is wrong, loose or ill fitting, remove the wire and give it another attempt intil it's correct. d. When castellated nuts are to be secured with safety wire, use the low side of the torque range (unless otherwise specified) and turn until the next slot aligns with the hole. e. The wire must be applied so that the pull is in the direction so as to tighten the fastner. f. Twists should be tight and even, and the wire between the fastners as taut as possible without overtwisting. g. All safety wire must be tight after installation, but not under such tension that normal handling or vibration will break the wire. h. Safety wire should always be installed and twisted so that the loop around the head stays down and does not tend to come up over the bolt head, causing a slack safety wire installation. i. The wire should be of a diameter to fill approximately 2/3 of the hole diameter unless otherwise called out.

Cotter Pin Safetying

The FAA recognizes one preferred method of installing cotter pins which we will cover here. There are some optional methods when space does not allow for the preferred method and those optional methods can be found in AC43.13-1. First and foremost the cotter pin must be of the correct size. If not called out, a good rule of thumb is the 2/3rds of the hole diameter but in any case the cotter pin should fit neatly into the hole, with very little side play. If you look closely at a cotter pin you will notice it has a long leg and a shorter leg. The long leg is intended to go over the top of the bolt or fastener and the short leg along-side the nut. 1. Insert the cotter pin with the long leg on top. 2. Seat the bulbed end of the cotter pin securely into the nut and bolt. 3. Using duck-billed or needle nosed pliers, grab hold of the upper leg and in one fluid motion bend to a vertical position.

4. Using side-angle cutters (dikes- to most of us) trim the short leg so as not to cut into the structure when bent. 5. Bend the short leg down vertically along-side the nut. 6. Using your dikes trim the remaining long leg so it will lay 1/2 to 3/4 across the end of the protruding bolt or fastener. 7. Bend the remaining leg over top of the bolt or fastnener ensuring it is flush so as not to become a snag. Here are some general rules that can help you in installing and inspecting your cotter pin installation. a. The prong leg bent down should not rest against the surface structure or washer. b. Never reuse a removed cotter pin, use a new cotter pin at each installation. c. If you mess up on the installation, remove the cotter pin and give it another go until it is installed correctly. d. The prong leg bent over the bolt end should not extend beyond the bolt diameter. This can cause a snag and injure you or someone else. e. All prongs should be bent over a reasonable radius. Sharp-angled bends can cause breakage. Lightly tapping with a light mallet can assist you in bending the prong legs on larger diameter cotter pins.

Other Safety Devices

Items such as safety clips ( other than those used on turnbuckles) and special fastners are pretty straight foreward as to how they secure the item properly but be sure to consult the manufacturers data and installation instructions to prevent damage to the fastener or adjoining component or structure.