Weird failure this week, just an FYI.

[DaV8or]

So I flew down to Fresno Chandler airport this week for another $200 hamburger. All was well until I went to go home. I cranked up the plane and it just cranked and cranked. Lately my hot restarts have been a real PITA and it's something I'm going to bring up at annual next month. Anyhow, about mid crank on my second round of cranking, everything electrical went dead on my plane. No more starter, no more panel, no more nothin'

 

I thought to myself, is there some sort of master fuse? I couldn't remember one. I tried several cycles of the master switch, and fiddled with circuit breakers. Nothing. Then I opened up the side panel and looked at the battery and all the connections. Everything was tight and looked normal. I jerked on the cables, but still no go.

 

Looked like I was going to be stuck in Fresno.

 

Fortunately it was a week day and that airport has no shortage of A&Ps. So many, that I had to actually choose which hangar to walk into. I chose one that was all about vintage airplane repair and had a lot of eally cool, rare old airplanes in there including an original Yak 18. The old guy that was working there begrudgingly agreed to have a look. He really didn't want to deal with me, but he walked out anyhow. He kept talking about sheared starter pins and didn't seem to grasp that it was a total electrical failure.

 

After poking around a bit, he realized it was a total electrical failure... he was stumped and didn't want to deal with it, so he pointed me towards another hangar down the way. These guys worked on everything he told me. So I walked further down the ramp and stuck my head in another hangar. This guy was none to pleased to see me either, but at least he brought diagnostic tools with him. Progress!!

 

On the way to the plane he thought my battery had shorted out. It's pretty new and I hadn't heard of that much, but he assured me it happens. Well, my battery was fine and he poked around some too and was also stumped for a bit. He then did something that was a really valuable diagnostic tip that escaped me.

 

He turned the master on and then proceeded to jerk the battery cables back and forth. What this did was cause the solenoid to intermittently click on and off. It told us that the problem was a connection issue and not some, order a part, get a motel room, tell my wife and watch HBO sort of solution.

 

It meant I could go home!

 

It was isolated to the battery ground cable and he said he could go get his tug and drag the plane over to his hangar where his tools were and I could really tell he didn't want to do this job and wished I would just go away. I suggested we just use the tools I had in the plane to take the cable off and save time. He jumped at this opening and suggested- "Well if you want to take that thing off and clean up the contacts up real good, put it back on and try it that might do it." If it still didn't work, he said he could make me a new cable.

 

He made his get away and I went to work. Now here's the weird part. The contact to the battery looked really good. So good I didn't think I could make it any better. The contact to the chassis was not as clean, but no where near what I would call badly corroded. It was pretty much all nice and metallic looking with just a few tiny spots of dark corrosion. If I had been asked my opinion on it, I would have said that it was good enough to work. It really didn't look that bad.

 

Not having any copper wool, or sandpaper, I just used my blade screwdriver to scrape at both surfaces until they were shiny and put it back together. I popped the master on and everything spun up! I then went back and jerked on the cable again to see if I could get it to go off this time. She held fast. So after walking back to thank the guy for his help, I gave it the ultimate test... the starter motor. She cranked like a champ and I once again pointed the nose for home!

 

Wow! What a long story for such a small problem! Sorry, keyboard carried me away. Anyhow, the pay off. Lessons learned-

• Adding a simple volt meter to the tool kit is a good idea.
• Adding copper wool to the kit is a good idea.
• It takes a really tiny amount of invisible corrosion on the connections to stop the electrical system dead in it's tracks.
• If you end up with a completely dead electrical system, the master on, jiggle test is a really, really good field diagnostic.
• Carrying tools in a 50 year old airplane is a good idea.

At annual, I will likely replace the cable just because it does look a little funky. Sane people must really question how owing an airplane could be any fun. I couldn't say because clearly I'm not sane.

[MooneyPTG]

Thanks for the info, glad it turned out alright.

What's with the all the attitudes. Fly in Wisconsin, friendly folks here!

[FloridaMan]

Had that happen on a car once and diagnosed it on a couple others in the past. A total electrical failure on start is often either a loose or bad cable. Corrosion likes to get into the stranded wire. 

[pinerunner]

I learned something. I never would have thought a bad connection could be so sneaky. I always thought, "metal on metal only needs a little bit touching". The part where it looked fine but it still turned out to be a bad connection.. Bet I'll be glad to remember it down the road.

[Mooneymite]

Thanks for sharing your experience.

[FloridaMan]

This usually only happens under heavy load, such as starting. My guess is that where the connection is poor due to corrosion, et cetera, and there's a high current, the area that is touching burns off like a fuse blowing and yields the same symptoms. 

[yvesg]

Last December, I went to get my GPS installed and as I landed at the airport where the avionics shop is, all my electrical went dead as I put the wheels on the runway on landing. The negatine lug connector sheered due to vibration...metal fatigue

Yves

[Seth]

Glad the repair was way less than a standard AMU.

 

Will keep copper wool in the "tool kit" going forward - smart call.  In the past, I would have just used the blade from a pocket knife, but this makes a lot more sense.

 

-Seth

[piperpainter]

I ALWAYS take a bag of tools with me. And because I work on the plane with my mechanic so much I know what tools I'll need for the jobs I may encounter. Knowing your airplane can save you time, especially if you're at an airport with nobody at all! With the places I go, I need to be capable of figuring this stuff out! 

[carusoam]

Had this happen six months ago to my wife's truck. Three miles away from home. The fully charged battery was a big clue...

Best regards,

-a-

[chrisk]

Is dialectic/conductive grease used on aircraft battery terminals? I'm assuming it would help with corrosion, but have no idea if it common or not.

[flyboy0681]

I'm not surprised to hear that the A&P's that you approached didn't want to deal with you as this has happened to me in the past as well.

 

I guess they are inundated with work, which is a good thing I suppose.

[John Pleisse]

+1...Had this happen in my Nissan Titan pick-up. Was momentarily locked in the car.

[N33GG]

Ditto had this happen on my 4Runner two weeks ago.  Contact on battery looked clean and perfect.  Would have lost a bet, but that was indeed the problem.  I was ready for something a lot more complex, but it was the connection. 

 

I always feel like that kind of thing happens to me to remind me that electrical engineering is more than convolution integrals and differential equations.

[scottfromiowa]

I ALWAYS take a bag of tools with me. And because I work on the plane with my mechanic so much I know what tools I'll need for the jobs I may encounter. Knowing your airplane can save you time, especially if you're at an airport with nobody at all! With the places I go, I need to be capable of figuring this stuff out!

Like mountain tops...

[scottfromiowa]

Hope you tipped your savior well...

[cleatus99]

Had similar problem with buddies maule, got hard to start so he replaced the starter with a new lightweight starter... After a month it was back to barely starting.... Well I was helping him look at it, he replaced the master relay before I got there... He went to start it up, barely was cranking.... Then smoke puffs out from under the instrument panel.... He reached up underneath it and yelled cause throttle, mixture cables were hot.... His P- leads had melted too.... I took a long jumper cable clipped it to the engine, and the negative on the battery.... It spun around like a turbine... The voltmeter showed resistance between the engine and the fuselage.... We scraped paint off ground strap attachment areas to engine block, put some no-ox on them... Replaced p-leads, and it started like it never had....