The International Cessna^® 170 Association

Does anyone have a drawing showing the wiring for the Ford alternator conversion on O300's? Had mine overhauled last week, but after reinstalling it there is no output. Need to see a diagram to be sure each wire is correctly hooked to the proper post on the alternator. Alternator has three posts that each get one or more wires. Each was tagged as they were removed. One of the outer shields that was attached to a ring lug along with another braided shield broke, but was reattached. I may have grounded out a ring lug to the alternator case or maybe I did something else wrong so I need to have this layman's drawing so I can chase out the vrs wires.

Cessna had a Service Kit available for this conversion SK172-22M back in the day. Actually parts for the service kit are still available but extremely cost prohibitive. The SK covers the complete installation and has a wiring diagram for the Ford alternator conversion. However in comparing this wiring diagram to later Cessna 172 and 150s that came stock with the gear driven Ford alternator there is no major difference. I have both wiring Diagrams available I could fax to you. If you are a member of the Cessna Pilots association you can get a complete copy of this Service kit from them. And as they will tell you these SK’s are copy written and are only for use by?

For informational purposes SK172-22M serial number affectivity is 17247747 thru 17254892. I used this Service kit document recently as the basis for a field approval. Which went through with out a major hitch. The local FSDO did not consider this Service kit as approved data for the serial numbers of aircraft that it covers even though it states that it is in the document. Why? because it was never incorporated in to the manuals for those aircraft and it was never actually approved by the FAA.

Jim

dear Pokey,

I too have the Service Kit drawings available for fax.


Suspect that these kits were installed with a wide variance from the kit drawings. Perhaps you can create your own "AS BUILT" drawing for your particular aircraft. It can inform now and save future "research time"

Will follow your post closely since I just turned up w same situation. New alternator, no out put.

What master switch is installed in your a/c.?

regards

gradyb

Grady, my master switch, as far as I know, is the stock Cessna 172 (1956) switch. If you want to fax the data I will gladly accept it.

fx 817-297-9818

thks

Frank I'll fax you the drawing I used tonight when I get home if I can remember I have 2-3 variation of the schematic --1 required 2 amp and the other like a 7 amp? your old master will work with no problems. If I forget call me. also have the 100 series service manual that has all of them 150-172 etc. ron

Ron, my alternator is one of those Continental Red Seal units mfg'd by FOMOCO & is a 60 amp unit. I will appreciate you faxing the diagram. I just hope I have a simple problem and haven't screwed up the alternator. Paid a guy $350 for repairs last Sat!!!

Gotta get this thing fixed for the trip to Cabool, Dwight, Dearborn, etc.

thanks,

Frank

Hmmm. Think I smell a possible warranty claim.

Frank,

The trouble with your alternator is that you are too close to George. Whenever my plane gets within 150 miles of George the alternator starts acting up. It happened at Wilmington and at Tehacahpi. At least he is not going to be at Detroit

Harold
N92CP

frank I forgot. I'll tell connie --she's on her way here-- to remind me. You didn't here this from me but any automotive alternator repair shop can test it and repair it for you. It's a standard fomoco series and a very good regulator is the automotive one from the auto parts store. its has no moving parts (can't think of the word). If they complain tell them it's for an airboat!!! Ron

Yea Ron, the previous 2 times I had work done on the alternator and starter I used a small town auto-electric shop. He did the work well and the charge each time was MUCH less than this "certified shop'" charge, but alas that small shop owner "went West" recently and I was trying to "do the right thing" by using an approved shop. I don't think the faa approved shop overcharged me, but it would have been less expensive at an automotive shop. Next time! Funny thing was I pulled the alternator off 8-10 yrs ago, had the auto shop fix it, put it back on using a little permatex, hooked up the wiring and it worked fine until I pulled it again at engine major OH. Didn't know at the time you were supposed to pull the tach drive & replace the one piece gasket. Guess I was just lucky!

One other thing Ron, "don't run off and leave Paul & I just because I made that Coon Ass comment ":lol: I'll buy you a beer or whatever.

And Harold, you may be right about George, I don't know, but if I don't have any luck Sat AM I am going to call George & see if he is an alternator fixer!

The REST of the story.....
Harold landed at one of the airports during the poker run and his alternator quit. He saw me land some time later to get my poker hand....and he complained that his alternator had been acting up for MONTHS....and now it finally died. He didn't know what the problem was. (Harold was flying again within 10 minutes, but I wasn't anywhere near when it had failed.)
Go ahead, Harold. You opened this can of worms.

The George curse struck again on the California poker flight and he had to make radio transmissions for me into one of the airports. He put his evil eye on it there and it again started working. Actually, it had momentary failures several times enroute to Tehachapi. It completely failed about a month after I got home and I had to have a complete new alternator.

George, does your schedule still have you unable to attend Dearborn. Everybody will miss you.

Harold
N92CP

I want to thank those who sent suggestions and/or vrs diagrams to assist me with my problem. I don't like to admit to messing up, but I did While reinstalling my alternator and reattaching the multitude of wires, even though I had carefully marked each group by alternator post (where they were connected), one of the cable shields that was attached to ground on alternator broke-----apparently was about to do so when removed---and I attached it to the incorrect post (field) which resulted in a direct short and burned up a wire in the voltage regulator. Someone who was a bunch smarter than me checked out the system and discovered the problem, corrected it and soldered a repair wire where the one burned in two in the regulator. Now it works fine although the orginal reason for pulling the dang thing off--whine in radio when transmitting with engine under 2000 rpm's, is still there. Now I need a new voltage regulator. I was given one that came off a Cessna 206 when the owner converted to a solid state one, but don't know if it will work with my set up or not. I seem to remember the one on ole pokey had two coils in it and the one from the 206 (also with alternator) has but one. Will have it in the plane just in case, but will need to do some research to determine whether it can be used or not. I think the one on the plane actually was from an automotive supply house & has worked well for many yrs.

I'm also doing a generator to alternator conversion on an O300C. Does anyone happen to have the SK172-22M instructions available as a pdf file for email or fax? I want to check over the wiring schematic.
Appreciate the help.


Chris

Please be advised that the only difference between an automotive alternator and one used for aircraft is the "diode" set up.
The aeronautical diode clips are more heavy duty having what appear to be larger diodes and heavier wire. A friend of mine,
who runs an automotive electrical repair and overhaul shop, says he is unable to buy the heavier aeronautical diode clips.
They will only sell them to FAA approved repair stations. However, I don't recall ever seeing any burned up diode clips and I
know that there a lot of the automotive parts flying.