I write a lot about motivation and philosophy, and most of the stuff rarely generates email, but if I write a piece that sounds cranky, people write in response. Below, a few thoughts from builders. keeping in mind that independent, intelligent people often see things from a different angle, I rarely expect builders to see eye to eye on perspectives, and it worth including that I am often more entertained by people I disagree with than people who see a subject the same way. I am open-minded, notice that “Guy A” gets the last word on the subject with his own letter.I wrote a long detail piece on plugs a few months ago, to read it type the words “Spark Plug Woody Harris” in the search block on the above right.
At the very bottom is a very thoughtful letter from Harold Bickford on the article Mastery or ?. Well worth reading -ww
From builder Matt Lockwood:
Good points (pardon the pun). Speaking for myself, I have learned tremendously from you, WW, thanks for being a pioneer.
From 601 Builder/pilot and DVM Gary Ray:
“You are not alone.
I have seen similar behavior in my profession. If West Nile virus is reported in the press then all animals that die in the next year were one of the unlucky ones that got it. Or if the Chinese contaminate dog and cat food with sawdust, then all animals that die of kidney failure must have been poisoned even though no toxic agent has been found, no animal gets sick when deliberately fed the suspected food, millions of animals that have eaten it have perfectly normal health and blood work, and none of the tissue damage found on necropsy of animals that die is related to other cases. Or, when a client states that they think their cat is responding poorly to a vaccine that he got two months ago and it is making him sick, they are not convinced by me when I tell them that the tire imprint on the white-haired abdomen probably has more to do with his current problem. “
From west Coast Pietenpol builder Pete Kozachik:
“Hi William, I’m having a Dickens of a time with your tale of two spark plugs; seems I used the wrong gap on my test run some time ago. The last line in your piece calls for .016″, but I used the 1965 Corvair Shop Manual’s spec, .030″. I used AC-R44F plugs, and ran the test using high octane no-lead gas as prescribed. What gap should I have used under those conditions? Same as for 100LL? One thing I noted after the run was some wet(?) soot on one plug, which I figured was due to any number of things, but not the wrong gap. What’s your diagnosis? Best wishes, Pete”
Pete, I included your note here in case anyone else read the story and got a detail wrong: .016″ is a gap that is correct for a magneto ignition, as on the Franklin in part “B”. Corvair should have a gap of .035″ and use ACR44F plugs. Other ones work, but if anyone wants old reliable, this is the best set, especially if you are trying to track down any kind of issue of experimenting with some other variable. We soot on a plug on a first run is often assembly oil from the engine’s build up.-ww
From Builder Mr. Jaksno:
“Sorry to hear this. Aviation does not suffer fools. The rant was well deserved, AND instructional. Thank you for being a ‘Lifeguard’. And thanks for being the Godfather of Corv-air!”
If you read the letter from Guy A you will see he is a pretty good cat, just missed it on the plug issue. A lifeguard will rescue people, (I tried it once, worked, but I promised Grace that I would let professionals and those clad in asbestos extract trapped people next time.) Just think of me as a guy standing on the beach pointing out where the rip tide you can’t see is. -ww
From Builder Bruce Culver:
“Don’t that make your brown eyes blue…..?”
And a response from the ever mysterious “Guy A” Himself, with whom I had a very pleasant 25 minute phone call today. If I ever sound cranky in email, it’s probably an attempt at humor gone bad. There is little between friends that can’t be fixed with a phone call……Guy A is obviously a thoughtful guy who considers risk management seriously, he just missed a basic important point on his engine.
I (Guy “A”) had night of introspection, and not much sleep, after reading this over a few times. I know that I’m *not* a taker of unmitigated risks, as you might infer. Instead, like nearly all long-time pilots, I recognize that flying, especially flying an airplane I built-in the garage with an engine not originally designed for a plane, is an inherently risky activity. And I believe that the risk can be reasonably managed through precise construction and maintenance, well thought-out testing, careful operation, and learning from the experience (and mistakes) of others.
I retorque my wooden prop at every oil change, and I do those at short intervals recognizing that Rotella-T and a $6 oil filter are not expensive compared to the engine. I have two batteries and an alternator in my electrically dependent airplane, and every year at annual, I put in a fresh battery in the #1 spot and move the #1 battery to the #2 spot, so that I always have at least one battery that less than year old. The manufacturer says the batteries should last 6 years, but what’s a battery worth when you’re in the clouds, an hour from the closest airport, and the alternator belt breaks?
I change my tires before they’re bald. I use flight following whenever I can and file flight plans when I can’t. I check the weather before I fly, every time, and I talk to Flight Watch a lot when it doesn’t look good. I use carb heat at low power whenever it’s below 75 degrees, even if I know the relative humidity is 20%. I attend FAA safety meetings regularly, because that one minute reminder of something I’m supposed to know might make the difference, making the two-hour presentation worth the time.
When I had a certified plane, I only used the specified plugs, and I cleaned, gapped and rotated them on a regular basis. So how did it happen that I flat-out “missed” the *requirement* to use the right plug with the proper gap in my engine?
I could try to explain that the plugs I used *are* listed in the spark plug cross references, and that I ground tested a range of supposedly acceptable heat plugs, found no apparent differences and stuck with the middle of the range. I could note that I’ve flown probably 400 of the 500 hours on my plane with those plugs. I could mention that modern cars with computerized adaptive ignitions are much less sensitive to particular plug heat and gap, so it wasn’t on my mind.
But all that would just be underlining the remarkable strength and robustness of the Corvair design. During all those hours, I was probably getting less-than-optimal performance and building up lead deposits on the valves. And a choice to use conservative timing (about 28 degrees max advance), in case I had to run on auto fuel, probably kept me from seriously damaging the engine.
So I’m just going to say, “I missed it, and messed up.” My bad. Experimental aviation is supposed to be a long journey of learning, and now I’ve learned this one,Luckily, no metal got bent and no one got hurt. ACDelco R44F plugs, gapped .035-.040. Got it.
Final note – If you also cannot find these plugs in your local auto parts store, try Rock Auto on-line (www.rockauto.com) for the best price.
On the subject of Mastery or ? Builder Harold Bickford wrote:
It seems to me that when you build something from components or better yet from basic materials you have to learn about craftsmanship, patience, accuracy and so forth. By it’s very nature homebuilding is not instant gratification and that is a good thing in a society that seems to want things right now for little or no cost. It is better to invest yourself and learn than to simply have someone else say “this is the airplane you want”.
Certainly part of the building adventure has been to visit and work with a fellow Piet builder. He ultimately chose an O-200 which he rebuilt. The Corvair engine mount he had is now in my shop along with a Corvair engine on an engine stand that will be torn down when it gets colder Meanwhile the wood for the fuselage is ready for cutting and framing up while we still have nice temperate days. True it is labor intensive (and we are on a budget) but the point is that when done the Piet will be a known quantity and at virtually every point Edi and I will be able to say “we built that”.