Aircraft Wiring 102

Builders,

After todays Aircraft Wiring 101 story, a letter came in from California 750 builder David Josephson. I share it for several reasons;

.

First, it is a view of what a builder can do if he wants to look at operating one level above the basic information I was sharing.  In all my conversations with David, what comes through is his unusual balance of technical-practical-detail application along with a very strong scientific understanding of the fundamentals of the question at hand.  When reading his take on a subject, it is a reminder that accessing this balance on any subject is what makes it interesting. While Tefzel and basic quality crimps and tools are what I use on planes, David’s notes are another step toward quality and away from the sub-airworthy.

.

Second, The letter is a reminder to people who work outside Aviation or the tech world, that industry specs and standards mean something in our field. Many workplaces and topics have very subjective standards of performance or none at all; note that experts in aviation long ago put out the most detailed standards for things as small at how wire is plated. Working in aviation, I don’t know 2% of these standards, but critically, I know for almost every question, there is a correct tested answer, you just have to look for it.  Understand when a guy says “It will be alright” what his is actually doing is deciding to stop looking for the known way and proven path, and accept the item in question as it is. Conversely, a guy who works in aviation knows that when in doubt, keep looking until you find the proven standard. When you think like that, you have become an aviation professional, even if your paycheck has a different address.

.

Third, The strength of the Corvair movement is the quality of the people we bring in as builders. Yes, I know the subject of Corvairs very well, but we have countless other people who know far more about engineering , electronics, flight, you name it. I like it this way, because it puts me in contact with people a lot smarter than me, and this expands my world and learning.  At Oshkosh a number of years ago, I was confronted by a man who leveled what he felt to be a damning charge against me; He wanted to publicly prove that I had changed my position on several technical points over the years. He was perplexed and disappointed by my response, where I told everyone present “Yes, I intentionally surrounded myself with smart people and then had the common sense to listen to them.”

.

c79323

Oshkosh 2013: East meets West in the tent. Two of the sharpest minds in the Corvair movement belong to Ken Pavlou of Connecticut, at left above, and David Josephson of California on the right. Both are Zenith builders. Ken has been involved in numerous projects in support of the Corvair movement. David is a nationally known expert on acoustics, and is interested in extreme noise reduction in aircraft. Both of these men find the Corvair movement the right focal point for their efforts in aviation.

.

____________________________

.

"William,

I have a few comments on your article, and a resource to offer. Your
recipe is good, but if people want to drill a little deeper they can
understand a bit more if they want. A well designed simple airplane will
only have a few dollars of wire in it, there is no point in scrimping —
but it may be possible to buy NOS military wire and terminals and get
good quality for less.

1. The softness of the terminal insulation is only part of the picture.
Good crimp terminals are made with nylon insulating sleeves, which is
soft and transparent. More important, there is a bronze sleeve inside
that crimps around the wire insulation under the nylon to actually
provide strain relief. The terminals with vinyl sleeves lack this part
and no strain relief is actually provided, only insulation, because
there is no mechanical connection to the insulation of the wire. Good
crimp terminals are made by Thomas and Betts, AMP and Panduit (although
those companies also make cheap vinyl insulated terminals that have no
strain relief,) and are compliant with the former MS-25036 series, now
SAE AS 25036.

2. The crimp tool must be the one specified by the manufacturer of the
terminal or compliant with the relevant mil spec, such as the AMP tool
in your picture.

3. An even more secure approach is to use uninsulated crimp terminals,
soldered if you like, and heat shrink tubing, which if clear can include
a typed label inside. (But! Solder only after there is a secure crimp!)
The crimp tool for uninsulated terminals like the original T&B Sta-Kon
is completely different from that used with insulated terminals.

4. The wire doesn’t have to be Tefzel (crosslinked ETFE), but it does
have to be aircraft wire. There are three criteria: the strands must be
individually plated, not bare copper or batch tinned, the stranding must
be fine enough to provide good flexibility, and the insulation must be
rugged enough not to deform when clamped, rubbed or mildly abraded.
Generally people use Tefzel because it can get hotter and not smoke
versus PVC, but the fumes from burning Tefzel are worse than from
burning PVC. Tefzel wire compliant with MIL-W-22759 is the best
compromise but is expensive. It comes in many colors and is stamped with
the mil spec number and gauge. PVC is okay but it must have a nylon or
fiberglass jacket, typically compliant with MIL-W-5086 or the later
MIL-W-16878. There are also good aircraft wire made to Boeing
specification. Teflon (PTFE) is okay inside equipment, but is softer and
more easily damaged. Teflon also more expensive than Tefzel because it
is usually silver plated — and in many cases the silver plating on
surplus Teflon wire has tarnished so badly you can’t use it.

5. There is a good stock of surplus aircraft wire, $8 a pound for mil
spec vinyl and $15 a pound for fluorocarbon (when in doubt they charge
you the vinyl price,) at Apex Electronics in southern Calif.,
www.apexelectronic.com. Joe has come back from retirement and will
usually find what you want, better if you go there. They also have
multiconductor milspec cable. They have mostly 16 gauge and smaller, I
recently bought spools of 16 and 20 gauge and even at $15 a pound it’s
1/4 the current market price, and you have a chance to get it in colors
if you are lucky. It is worth a visit, it’s one of the remaining
aviation surplus stores on the west coast. Take a flashlight and good
glasses, the lighting inside isn’t so great.

6. The Delphi Weather Pack connectors are great, *if* you buy into the
whole system. The parts are cheap, but you need to have the correct
sealing glands and the correct crimp tool or the reliability of the
system is lost. If you really need to be able to disconnect things
quickly, fine. Frankly I prefer to have fewer connectors and am willing
to spend a little more time unscrewing terminals.

7. NO BARREL SPLICES. You cannot inspect the crimp of a barrel splice,
so you have no way of knowing it’s secure. If you need to splice a wire,
use two knife blade connectors like AMP 32446, in a length of vinyl
tubing tied with nylon twine.- David”

.

Aircraft wiring 101

Builders:

I bring this up because it is the most common mistake I see in homebuilding, and oddly enough, it is about the easiest skill to posses, the tools are cheap, and there is no valid reason for doing this wrong……but 75% of the planes I look at have terrible wiring, particularly the terminal crimps.

.

Below is a photo that has been on our main page for nine years. It is also in our Zenith installation manual, and I have reprinted it before. Search “wiring crimp” on the main page search block and it pops right up. Think most people read it? The wiring I see suggests otherwise.

.

This isn’t an academic nor style point, this is airworthiness 101. Two years ago we had a builder spend several months of very frustrating searching, looking for a defect that made his plane have a bad miss at times. He sent the distributor back to me more than once with the clear implication that it was defective even though it tested fine. Next suspect was the certified yellow tagged carb. All the while, the people at his airport are being treated to a demonstration they perceive as “Auto engines are unreliable” and “Not even the guru knows how to fix it.” When it was all said an done, the 100% culprit was a shitty crimp done by the builder on the 12V line going to the coil. I do not like my designs and work being considered as the prime suspects when the issue is people who are doing wiring at a quality we could expect from a weed smoking high school boy in 1978, trying to install his 8-track player in a ’69 Valiant, so he could listen to his new Ted Nugent Cat Scratch fever tape.

.

Your Corvair needs good wiring on the ignition system to run properly. You need to make as few connections as possible, and have a simple design for the critical wiring. Leave out all the junction strips and additional connections. To make the distributor easily removable, consider using the Weatherpack connector we have on EP-X distributors. If you are headed to a college and already have a distributor, bring it, I will upgrade it on the spot.

.

Now, as we read this, some dope is going to post a link on a discussion group saying that “Corvairs have critical wiring and that is why I am glad I picked an A-65 Continental with mags.” OK, get this: Hand prop planes with mags have an even more critical connection than a Corvair. The P-lead grounds to the mag have to be done perfectly, because you count on them to protect your life every time you touch the prop.  If one of the P-leads has a shitty crimp, the key can be in the off position and the engine will easily start or kick over with lethal force.  Think I am exaggerating? At the very bottom of this story are a few photos of a great guy Gary Collins, who attended many Corvair Colleges and built a very nice Corvair Powered Carlson Sparrow II. In June of 2013 he was struck by the prop on his Lycoming O-320 powered Tailwind while simply working in his hangar. He died several days later.

.

I want to clearly state that I am in no way implying that Gary’s plane had anything wrong with the wiring or he that was an unsafe guy.  He was an outstanding human being, and I include his accident here because I want to make builders understand that accidents involving props are not a myth, and they do happen. (Gary did not build nor wire the plane that killed him) By putting a person’s name on one I want people to think about this as possible. I have seen a number of homebuilts with poor wiring and magneto ignition. You can assume the builder also did poor work on making the P-leads. Moving such a plane by touching the prop, or rotating the prop to prime it is the absolute equivalent of pointing a loaded gun with a known defect in the safety at your head.  All planes have critical points where the wiring quality must be 100%. Anyone who implies it is OK to have “It will be alright” level of quality on the P-leads of planes with mags is a dangerous fool.

.

Go on any internet forum on homebuilding you like and bring up the topic of wiring. You will get hours of reading and opinion on electrical theory, written by people who think they have something to teach Nikola Tesla. It is all a giant waste without simple crimping tools and skills, but the armchair electrical engineers never bring that up. Good homebuilding is about mastery of basic skills like crimping. It is that simple.

.

———————————————————

.

Here are the basic elements of good wiring for experimental airplanes. Tefzel clad wiring is available from all the  aircraft supply houses. This jacketing is many times tougher than typical insulation, especially at elevated temperatures.  Real aircraft grade terminals have soft insulation, which does not crack when it’s crimped. The crimpers in the photo  above are available from mcmaster.com. They’re just under $50, and worth every penny. There are many good books on  aircraft wiring, and some discussion groups about it. Unfortunately, most Internet discussions devolve into giant debates about  massive redundancy, counter EMF, diodes and bridges, and how the letter i represents the square root of -1, which can  be used to describe the behavior of alternating current. Perhaps you, like me, get sleepy reading this stuff and wonder  what it has to do with your airplane. Answer is: not much. But do not wholesale cash in all of aircraft wiring. The  basic materials and tools are important to incorporate into your own project. Don’t let the complex discussions  completely turn you off.

Above are things that should not be in your aircraft workshop. Typical automotive store wiring has very soft, poor  insulation. The crimpers do a terrible job, and the terminals have hard insulation that cracks when crimped, and is  then prone to falling off. Wiring like this is one of the first things that catches my eye when inspecting a project or  scanning a photo. Your DAR, when inspecting the airplane, will notice this also. Many DARs I know are very reluctant  to sign off airplanes with this type of wire. Five minutes of exposure to the right stuff and you’d never consider  using the wrong stuff again.

————————————————–

.

The following excerpt is form a story I wrote called Spark Plug Issue resolved….. you can click on the title to read the whole story after reading and thinking about the words below. It is fine to have dreams and complex interests in aviation, but you must also strive to cover the fundamentals. like being able to do a 100% airworthy crimp. Being able to fly a jet is an admirable skill that takes real effort to learn, but in successful homebuilding the basic stick and rudder guy who spent 30 minutes learning how to do good crimps is going to have a lot more success than a 10,000 hour jet pilot

.

“In an average year, I will get 200 emails asking about things like constant speed props and elaborate injection systems. If you read all of them, it is easy to tell that 95% of these come from people with little experience. If I lined up these 95% and asked them to install a distributor and time it, or to explain to me how you could tell if the engine was on the top of the exhaust stroke of compression by looking at the motion of the rockers,(both things we teach at Colleges,) I am sure these people would be at a loss. Is there anything wrong with their dreaming of injected constant speed planes? Of course not…if the extent of what they came to aviation to do is dream about things. Conversely, if actually achieving things is the goal, dreaming can not take the place of a rock solid foundation of the basics.

None of us were born knowing this stuff. I am glad to teach it to anyone who wishes to learn instead of day dreaming. I can make a very good argument that the builder who creates and masters the operation of a basic aircraft, is a lot safer, and will experience far greater rewards that any builder operating a plane he really doesn’t understand, or is sketchy on the details of a complex aircraft’s function. The guy with the most basic plane has won the game. The guy who consigns himself to daydreaming has not lost the game…..he wasn’t ever playing.  Once the basics are mastered, then moving forward can be done with the understanding that you are not posing or posturing as your own mechanic, you actually have earned the confidence in yourself, the real reward for knowing the subject. -ww

.

—————————————-

.

I took the comments below from Gary Collins’s Facebook page. They were written by his son in law as Gary lay dying in the hospital. Learn from this tragedy. Gary was a life long aviator with a very safety minded attitude. I worked with him at many Colleges, and I would never have suspectled he would have this type of accident. Learn to treat props with the same care you handle firearms.

.

 “I will miss you Gary.  You have always been very generous with me and Jennifer and the girls.  I enjoyed the time we spent together.  I pray that you can still hear the words of love that your family and friends give as they visit you in the hospital.  I pray that you have no pain or discomfort in your last days.  And I pray that you find peace with the Lord so we can see each other again someday in heaven.  God bless you.”

Photo

Photo

Photo

.

Pietenpol Weight and Balance article source

Builders,

I spoke with Doc Mosher last week. As all of you Piet and Grega builders know, Doc and his wife Dee Just finished a six year run at producing the Brodhead Pietenpol Newsletter. It was an outstanding effort that brought back the whole community spirit around Pietenpol building and flying.

.

Doc is not a guy to blow his own horn, but I have known him for long enough that he will forgive me if I do it for him. We all understand that newsletters are often covered by the guy in the club who has free time, is good with word processing, and let me put this politely, doesn’t have the strongest of flying nor building backgrounds. It often produces a newsletter with good graphics, but very weak technical and editorial content. Although well intentioned, many editors don’t have a lot of broad based flight experience.

.

I hold that the last 6 years of the BPN is the ‘gold standard’ of the history of the publication, and newsletters in general, because Doc is the antithesis of the typical newsletter writer.  Lets start here: He has the ultimately rare distinction of holding both of the FAA’s highest awards, The Master Pilot rating and the Charles Taylor Award.  Get this: just to apply for these, you have to be an active, accident free pilot for 50 years, and for the Taylor award you have to be a working A&P for 50 years. (I just figured out that I can’t even get my application in until 2041!) Doc is a very modest guy and I knew him for several years before I discovered he had the Charles Taylor award. He used to politely listen to me, letting me believe I had something to teach him about engines.

.

I used to think that you could measure writers and editors by their written content. Doc taught me by example that you also have to consider what the really good choose not to include. This judgment only comes with a depth of knowledge of the subject and a insightful understanding of people and their actions. If you have been around Pietenpols for 5 years this might not grab you, but if you have been around a long time, Doc’s judgment and choices are easily appreciated.

.

I have been fortunate to know people with encyclopedic knowledge of the history of aviation, but when you listen to Doc speak of  Dee Howard, Ed Swearingen and Schweizer brothers, he isn’t speaking of historical figures, he is speaking of friends. His first hand experience through some of the most interesting periods in flight is captivating. He is a very keen observer of the human condition. His stories are always seen through the eyes of humanist who sought out the good in people, forgiving their frailties if they were real characters.

.

Conversational topics with Doc are unpredictable; he might comment on being James Brown’s corporate pilot, having Thelonious Monk as a neighbor or Hunter S. Thompson as a regular in the bar Doc owned. Or he is just as likely to spend the evening speaking about a plane that is the creation of a builder he just met today. Memories are cared for but not worshipped, what can be done next always a better topic that what has passed.

.

In a previous story: Pietenpol Weight and Balance project I covered a description of doing the 5 part series on Weight and Balance on Ford, Continental and Corvair powered Pietenpols.  It was a project I had thought about doing for a long time,  but I would like to be publicly clear that it is my immense respect of Doc and the quality of the newsletter that he and Dee were producing that motivated me to do the work and make a lasting contribution that might measure up to his standards. Few builders know it, but Doc has painstakingly collected and carefully authenticated an incredible collection of original plans data on Pietenpols. It is called “the Packet” and it fills a 2.5″ thick 3 ring binder.  I wanted to produce something that might add a few pages to this historical record.

.

Doc did not amass this information to occupy a dusty shelf in the EAA’s reference library. He put it together to be a useful tool to today’s builder; to make the next generation of Pietenpols  a little better than the last. To make the specific Weight and Balance data articles accessible to builders, Doc has offered them in a single package to builders. If you would like a set, stick a $5 in an envelope and mail it to Doc’s address below. If you wish to make it a little easier, send $12 and perhaps he can send it to you in a flat rate priority mail envelope.

.

While your at it, you can include a thank you note to Doc and Dee for their years of work on the newsletter. They don’t need the praise, but you will feel better about yourself knowing you expressed gratitude for being the beneficiary of an excellent newsletter.

.

Doc and Dee Mosher

1071 Meadow Lane

Neenah, WI 54956-3936

.

Blast from the past, summer of 2000: Doc (in the beard) and I in my hangar at spruce Creek for Corvair college #1.

————————————————-

To read a little more about Doc’s background in aviation, get a look at this story Ed Leinweber wrote about Doc last year:

.

http://www.midwestflyer.com/?p=6720

.

New stories this weekend.

Builders,

We are back from our great College in Texas, but we are now only 22 days from our College in Florida. To cover all the events and topics on the table, we are working to have 6-8 new stories this weekend on this website.

.

I am sending out this advanced notice because builders who check in only once or twice a week occasionally miss the first story or two when we publish a chain of them in quick succession. With CC#29 just around the corner, it is important that builders catch a quick read on all of the topics we cover, and not get inadvertently excluded for an event.

.

While we were in Texas our phone machine filled up as it does from time to time. Our phone/internet line was put back in order by ATT today at noon for the first time in 36 hours. We have a little catching up to do on communications, but know the answering machine is now clear and the line is re-established with an all-new router system. The Coffee pot is full and we have several stories pre-written for publication. This promises to be a very good weekend for communication of ideas, stories and enthusiasm.

.

The story topics include:

.

Corvair College #28 coverage including photos.

Corvair College #29 sign up in progress and prep work.

More notes on Corvair weight and balance

Updates on wiring your project.

Update on 601 builder Spenser Rice, (JRB)

Notes on engines for sale on the internet.

Oil line options for builders.

Engine displays at Sun n Fun.

.

Stay tuned, it will have a better effect on your flying season than watching television.-ww.