Just trying to get more than a couple of brains on this one, I have a capable A&P on it but would love to have your input.

Belts/Wires/etc check good beneath the light of an L.E.D. moon. After about 15 cycles spaced out a while, it was noted that about 50% of the time when the Alt is switched on, it shows good charge for 30sec-2min and then quits abruptly. The other 50% it shows nothing. Speculation is that the voltage regulator may be kaput. Engine has about 230hr since new and I assume the alternator has the same.

Plane is parked at a semi-remote field so the more ideas we have and things to bring with to increase the odds of fixing it in one shot, the better.

Thanks in advance,
SD

Can he wire a light or a meter between the field post of the alt and Neg. Test static by turning on the master, you should have 12V at the field post of the Alt to neg, if not ck the power going to the Reg. there should be 12VDC from master buss, if there is power to the Reg and none @ the field post the reg is bad Running test: if while running the light goes out or the volt meter that is hooked to the Alt field and negative, drops way down or to zero the voltage reg is likely, if the light or voltage stays high then the alt is at fault, use great care when tightening the alt belt DO NOT over tighten it !
Depending on which alt you have, early franklin 55A check the tag on the side, had an AD note on the due to the rear bearing, when they fail they will hammer the acc. drive there is a direct replacement 60 A alternator from Kelly Aerospace Susan should have the part number.
Call if I can help, Joe 760 832 2736

I wanted to add to my last post, there should be two field posts on the back of your alternator, at least on my Presto lite there is one side goes to negative/chassis ground and the other to the Reg, lift the Reg lead and check OHMs across the field of the alt. I think it should be about 14 ohms if it’s much higher than that either the brushes are worn out or the field has gone south. Is the alternator oily? If it is the brushes may be hung up or worn out. Look at where the case halves contact the stator look for black dust, if there is black dust it’s likely that the Alternator case bolts have loosened up and the alternator has shaken its self to pieces, it’s likely the stator windings are shorting to the case or have broken off.

Thanks a Ton Joe, I've passed this thread along to the attending A&P. I'll definitely update as things unfold.

SD

I have no advice about how to fix the problem but question if I may. Why not just finish the flight without the alternator? I don't know where he was going or anything about the aircraft systems but first thought to me is he should have been able to get it to a non-towered field that would be much closer than 300 miles. I recently listened to Mike Busch's webinar "AOG: When You Aircraft Brakes Away from Home" and the gist I got was that you don't put the plane in an unfamiliar shop unless you have zero options. What am I missing that made the pilot stop the flight or was he just being cautious?

Whee that's a very valid question. In this particular case, as the ferried bird and chase plane approached with the intent of going over top of a class B darkness was falling. The power (used sparingly to this point) was switched on so as to have lights and transponder. Prior to getting on top of the B the battery gave up and all the lights, transponder, engine inst, fuel indicators etc went away. At this point the very prudent decision was made to knock it off and regroup on the ground. Home plate for the ferry crew was just over an hour and a half away via chase plane so rather than sleep in some dump that close to home they went home and slept in their own beds, can't say that I blame them.

My understanding of the current plan is to do just what you mentioned, put a good charge on the battery in order to get it started (nobody wants to hand prop this one) and be able to monitor engine inst and fuel periodically, get it home and do proper repairs.

If he is planing on doing that, remove the belt from the alternator, if the alt. is failing from a bad bearing you don't want to trash your acc, drive.
Accessory drive failures on Franklins have been known to cause sudden engine stoppage.

Good point. Will do.

SD

Thanks for the response SD. I would have done the same with night approaching and needing to cross class B.

WELL,,,, WE ARE WAITING, is it home yet? What was wrong, what does the new bird look like?

172heavy wrote:WELL,,,, WE ARE WAITING

Ha! You and me both. You probably more patiently though

The ferry crew's schedule was hammered until today so they went up early this morning with the intention of charging the battery, removing the alternator belt, and boogieing home. Assuming all went well and they were able to get it restarted at the required intermediate fuel stop, this bird ought to be showing up any time, I'm at my hagar chewing my nails as we speak

I try to be a "no news is good news" type of guy so the fact that I haven't been informed of any further delay is good. Rest assured though, it has taken a lot of restraint to not be blowing up my ferry pilot's phone.

Did you takeoff yet?
Did you leave yet?
Is everything going ok?
Did you takeoff yet?

God help me the first time one of my kids goes on a long cross country trip.

SD

Just when I thought all hope was lost, as I stood shooting the breeze with a hangar neighbor, wistfully staring at final. Hey, Theres a yellow plane, "Sure would be cool if that was a Stinson" "wait a minute, thats a LongEZ following it, they took a LongEZ to go get her, son of a..... There she is"

I took video of the landing but like a jerk I stopped recording before the ol girl taxied up to the hangar. I'm kicking myself for that because this thing sounds BAD ASS idling, somewhere between 72 Camaro with a lumpy cam and cold Harley.

The flight home from the several day intermediate stop went well with the alternator belt disconnected. Time to figure out what thats all about. Joe I'll likely pick your brain a little further before all's said and done.

Theres still LOTS of looking in holes and touching and fooling with things as the bird showed up just as it was time to get home to my family, I was able to chock it, ohh and aahhh for a few minutes, and come to the conclusion that whenever bigger tires are appropriate, I'll have to find a different hangar because this one will be too short :-/



I'll sleep differently tonight.
SD

I like it!

Looks great!

Plane looks great!

Straydog wrote:

I'll sleep differently tonight.
SD

That is a great-looking airplane! Somehow this is the first yellow Stinson 108 I've seen. Very nice!

Glad to see its home safe, I saw it for sale on BS and lusted after it my self. Got lots to share with you and your A&P or IA about the Franklin,
I feel like Joe COOL when I taxi in, went to a QB event several months ago, after taxing to a tie down, I commented to my friend that we had the coolest sounding re sip at the airport, just as I said it a P 51 blasted off, OK the second coolest.
PS: My hanger is set up on treated 4X4 s to accommodate a 210.

Thanks a ton for the kind words fellas, I'm pretty well beside myself about it. There are a few gripes to work off but it's exactly the plane I've wanted for years. I'll try to do a proper new ride write up tonight w/ all the vital stats & some more pics.

SD

I've had two experiences I had with an alternator going tits up (as in, just flat-ass quit). Both times, it turned out to be broken wires at the alternator connections. In both cases, the wire had corroded right where it went into a crimp-on ring connector. It was pretty obvious in one case (pulled on the wire and out it came), the other one not so much. The wire didn't pull out, but after I pulled the alt off to be checked out (putting out 50+ amps on the bench, thank you very much), I noticed when reinstalling it that the ring on the end of the field wire could turn 360 degrees plus on the wire with no resistance. Cut it off, crimped on a new one, and wallah! back to 13.8 volts output again.
I guess the moral of this story is to check (and re-check) the simple shit first.

Well the holidays and all the travel, eating, travel, and some more eating have once again given way to life as usual so I'm now back on task to get this alternator thing squared away.

The ol' Prestolite alternator went to a local alternator/starter shop today to be bench tested, the result......deader than a popcorn fart. Good news in that the issue has been identified, now how to get it rectified. I'm told there's a shop in Van Nuys called Aero Accessories that can rebuild it but it was after closing time by the time I was given their name and I doubt they're open weekends so I gotta wait to see if that's a viable option.

Is it worthwhile to have this old one rebuilt for ~$200(speculation) or is it not worth the hassle and I should just replace it altogether?

If I choose to replace, my options as I understand are; find one with the same part No. ALH-5106S or find one STC'd for this motor? I'm a bit confused about this since I've looked over the TCDS for this engine (E9EA) and don't see a particular alternator specified. Can someone clear this up for me?

172heavy I did note your advice about the direct replacement from Kelly and will get in touch w/ Susan as soon as I can.

Thanks in advance
SD