Comment

Comment by Bob Pustell on June 25, 2014 at 10:04pm

Hey, Don-- note the safety wire job in Brian's picture. The twisted wires are set up in a way that has no slack between the two interconnected bolts. The twisted wires are arranged so that if one bolt head tries to back out it must (by pulling on the safety wire) make the other bolt tighten (which is hard to do because the other bolt is already torqued down hard against the surface.) Therefore it is very unlikely that either bolt will ever loosen. Also note that the sharp end of the cut off twisted wire "stub" is bent around on itself and the sharp end is nestled against immoveable structure so that the sharp end cannot cut anyone's flesh if they reach near the wired area.

This looks simple but it takes some practice to do well. Do not hesitate to cut your wire off and start over if it ends up being loose or messy looking. A tool that helps do this job is a safety wire plier but you can also do nice work just twisting the wires by hand and using pliers and diagonal cutters to pull and cut the wire. Safety wire pliers look like this. http://www.aircraftspruce.com/catalog/topages/econwiretwister.php?c... The depicted pliers are a very basic unit (which I have) and they work quite well. You can get fancy versions up to about a hundred bucks but do not really need them, in my opinion. The few times you need reverse rotation you can just clamp on with the cheap pliers and then rotate the unit by hand in the "wrong" direction rather than use the rapid spin mechanism that the unit uses to spin the wires in the "normal" direction.

Safety wire is made from a very flexible ductile alloy of stainless steel and comes in three diameters. You should get a roll of each size wire to go with your pliers. Or, you could buy this kit...  http://www.aircraftspruce.com/catalog/topages/safetywiretwister.php... The screwdriver looking thing in the kit is a handy tool for twisting safety wire in confined spaces, it is tedious but gets the job done in awkward situations. There is also soft brass safety wire but it is seldom used in modern aircraft upkeep, mainly used in antiques, you should not need it.

When you pull safety wire out of the roll, DO NOT just pull it straight. It comes off the inside of the roll with a spiral bend in it. If you just pull it straight you can easily kink it which generates a possible failure point. You need to sort of gently roll the wire straight while preventing kinks with your hands. It is hard to describe but easy to do, just be sure to not pull any kinks straight or your safety wire job may fail later on.

You will really enjoy learning to care for your plane. That is one of the joys of a homebuilt, you can legally work on it yourself!

Comment by Brian A Manlove on June 25, 2014 at 9:32pm

Remove the 2 safety wired bolts.  DO NOT remove the other 2 nuts, those hold the "slider pins" on.  After you remove the 2 bolts, the inboard brake pad comes right off.  The brake pad on the this side remains bolted to the axle assembly. When you remove the cotter pin and castellated axle nut on the outside of the wheel hub, the entire wheel & hub can be pulled right off the axle.  

Comment by Bob Pustell on June 24, 2014 at 12:35pm

I just got back from a trip (a funeral and a wedding, sort of closes the loop of life, I guess) and found your reaction to my last post, Don. I am sorry if I offended you, that was not the intent. I have seen too many people who know mechanical stuff get into trouble working on airplanes. They are NOT the same as trucks, cars or motorcycles and the knowledge does not transfer. As Brian pointed out, a bolt that feels "right" in tightness is usually overtorqued in an airplane -- use a torque wrench on pretty much everything until you get the feel for it, and even then a torque wrench is your best friend.

About the safety wiring -- I was not saying that YOU did it wrong, I was saying it was done wrong. Just because the last guy built a plane does not mean he or she knows everything there is to know about good work skills. The fact that it is not really right is what I was trying to convey, I was not assigning blame or pointing fingers. The particular location of that improper safety wire job is not an area of real concern, but it makes me wonder what the safety wire jobs are like in the rest of the plane.

I am a former military (and airline) flyer (Air Force in the Viet Nam era) and also a former professional auto mechanic, very similar to you. I also have been flying light aircraft since the 60's. None of those things qualified me to work on a plane. I watched pros work, helped informed homebuilders and owners of factory planes build and/or work on their planes and also have attended many seminars at OSH. There is a very specialized learning curve to climb.

Finally, my reply that caused you offense was a bit terse because I was headed out the door to get to a funeral. However, I felt strongly enough that you should be informed of the learning curve ahead that I took the time to bang out a quick (and perhaps tactless) entry in this discussion. I did not want your family to have a funeral to attend. It is remarkably easy to do the wrong stuff in aircraft maintenance and sometimes the results are fatal. A few comments from a chat group do not get one qualified. Work with folks who know what they are doing and/or read some good books. The Tony Bingellis series of books on homebuilding would give you an excellent start. You could skim over the parts that are exclusively about the build (but they are interesting) and focus on the parts about hardware, wiring, torque, safety wire, etc etc etc. EAA sells the books.

Anyhow, welcome to Zenith-land. Do not let accidental grumps like me sour your view of us.

Comment by Brian A Manlove on June 23, 2014 at 1:15pm

P.S.S - I can get you pics of this stuff later this week, my plane is hangared away from home.

Comment by Brian A Manlove on June 21, 2014 at 9:06pm

P.S. - when I say "outboard brake pad" - that is outboard of the wheel hub, not the airplane. It's really the inboard brake pad, relative to the landing gear... hope that makes sense.

Comment by Brian A Manlove on June 21, 2014 at 8:59pm

It's OK!! I am a USN vet and I worked on aircraft, and I've been an automotive wrencher for 45 years - but these little airplanes really are different beasts. The hardest thing for me was the relatively small size of nuts & bolts and the light torques required - AN-3's will not even seem to be "tight" by automotive standards - but it really is critical on these airplanes, that they be correctly done. If you look at your brake disc, brake, the outboard brakepad is held on by 2 safety-wired bolts. If you pull those bolts, the brakepad will slide out & off... then pull the cotter pin & axle nut off and the entire hub assy. will slide off the axle. It uses a regular automotive-style tapered roller bearing both inboard & outboard, which is "packed" behind a stainless shim washer and a felt seal. It's also a REALLY GOOD idea to repack those bearings at the same time, since you will then be absolutely sure that it has been done. Once you have the hub/wheel off, you should be able to get the inner tube & tire reset right, and you'll know how it goes back together.

Comment by Don Forwood on June 21, 2014 at 8:38pm

Brian
Thanks again for input. I truly appreciate helpful suggestions from members of the group. Your last was extremely helpful. I was not aware of DVD you referenced and I can easily see the benefits
I am not a bit experienced with a/c wheels and tires, so the DVDs will answer a variety of questions. Please be assured that I am extremely safety conscious and maybe a little thin skinned when lectured.
I would again remark that my perception of a builder forum is support vs judgement.
I did not build the plane and as a former USMC jet attack pilot and a seasoned mechanic I am aware of my limitation (as Dirty Harry says) and safety has been a primary component of my being since starting flight training in 1966 and cemented by US Navy flight school
I strive not to anger members, as I know the future will bring more opportunities to seek assistance. I guess my Marine training commands that I defend my position. (I did seek out advice from a group of experienced builders)
I really hope I don't anger other members.

Comment by Brian A Manlove on June 21, 2014 at 6:41pm

I don't think Bob was trying to be condescending - he has YOUR SAFETY in mind... and based on your questions, it does indeed appear that you have not much experience with airplane maintenance. Of course you can learn it, nobody doubts that... and you obviously have the ambition to tackle the job. I personally think your best bet would be to get some help from someone who has done this, and watch & take notes, and you'll never have to ask again. I personally watched the HomeBuilt Help DVD's for my plane (650) that shows disc brake assembly, tire mounting, etc. and was worth every penny. I also had the same question about the valve-stem nuts that came with the inner tube, I called Caleb at tge Zenith factory, and they are not used on the Grove hubs. You just position the stem in the hole that is formed by the 2 hub halves. If it sticks out too far, you will either have to get a new tube of the correct stem length or re-mount your fairing bracket... Did you call Zenith to get the correct tube number?

Comment by Don Forwood on June 21, 2014 at 10:56am

Bob,

I appreciate your  comment, and the reason I posted questions is to ensure that items are done in correct, safe manner. As I DID NOT BUILD this A/C, I use this forum to get advice from experienced builders. As for my experience with mechanical items, you are way off base. Too many assumptions. I spent my college years (late 60's) as a mechanic on a Interstate service center. With hundreds of semi tires and split rims in my background, I do not need to be reminded of the safety aspects. With that said, I do want to thank-you for input, excluding condescending remarks. I was of the assumption that the forum was meant to share experience and advice, not "tee-off" on someone with legit questions.

If roles were reversed, I would have attached pictures, documentation (if I had any) etc to assist a fellow owner. The safety wired brace was on the starboard wheel, and was done by the builder, not me. This is the first time I have removed the skirts.

Comment by Bob Pustell on June 20, 2014 at 9:46pm

As Dan says, riviting the brakes is no problem with the right tool. And the tool does not cost much. I am unaware of pre-assembled brakes but they may be out there somewhere. I'll bet they would be expensive.

Yes, you take the wheel and brake disc assembly off as a unit. Yes, you take the brake off to do it, or you cannot pull the wheel assembly off the axle. By the way, be sure to deflate the tire (if it is still holding air before removal) BEFORE removing the axle nut. If the through-bolts have failed or if the wheel half has failed around the bolt heads, the tire pressure inside the tube will pop the wheel halves apart when you remove the axle nut and parts will start flying (because the axle nut is all that was holding the halves together if the attchments have failed.) That is a very rare failure, but it can and does happen and people have been hurt removing a wheel with pressure still inside it.

I am not trying to sound condesending, but if you do not know all these basic things you have no business taking a critical aircraft system apart and putting it back together. Get some good books and learn what to do. Hire a certified mechanic (or find a knowlegable aircraft owner who does a lot of their own work) and work with them the first time. Doing it wrong in aviation can have fatal consequences.

In your photo the safety wire on the two bolt heads for the pant bracket is not really correct, by the way. (Speaking of doing things right). As set up, both bolts can loosen and the wire will just shift along with the bolts. The safety wire as pictured will stop the bolt heads after they have rotated a half turn or so, but things will be loose by then. The wire should be installed in a way that does not let either bolt head move in the remove direction, ever, even a little bit. Also, the pigtail of cut-off twisted wire should be bent back on itself so that no sharp edge is available to slice open your (or the next worker in that area) fingertip. Again, a decent book or a few minutes spent with somebody who knows will help you. It is not hard to do but it should be done right.

It is legal for the owner of a homebuilt to work on it themself, but that does not make it safe unless said owner knows exactly what they are doing. Please get some training rather than making guesses or improvising your own proceedures. Most things in aviation (including working on the machines) is done in a certain way because people have died or been badly injured doing it different ways.

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