front alternator inop

JeffAxel · #1 09-15-09, 09:21 PM

I can rotate the fan freely with my finger, I am guessing the drive coupler is shot. Any reasonably priced source for these?? Aside from a lot of cussing, any secrets to share regarding getting that thing out of there?? Gonna be sure the alternator is ok before reinstalling........thanks

skymstr02 · #2 09-16-09, 07:51 AM

There are two different types of couplings, the older having two rubber bumpers and a cup shaped retainer. The newer being a one piece design. The newer style are repairable at a cost some where around $500 (two year ago price).

If you have the older style, please be aware that any loose pieces can fall into the engine (not good) if they are not retrieved as the alternator is withdrawn from the mount pad. Keep a mechanics magnet handy for this evolution.

Go ahead and remove the battery and battery box, and any air hoses (SCAT) out of the way before you begin. Be careful from man handling the wires on the back of the alternator, remove them before you start and tag their location.

Your mechanic can give any other tips that he has as far as what he wants since he will have to return the aircraft to service after the task is completed.

stackj · #3 09-16-09, 10:48 AM

From the Skymaster Maintenance Manual.

After opening files - Click on the open image to see more clearly.

skymstr02 · #4 09-16-09, 01:39 PM

I've removed my fair share of front and rear alternators, and have never had to disconnect a fuel line or cowl torque shaft to remove the unit. A little creative twisting and turning, and the alternator will come out just fine.

PierreR · #5 09-16-09, 10:03 PM

I did experience a total front engine failure 40 minutes into a flight right after having the front alternator replaced. All of a sudden the engine feathered on me, the fuel flow dropped to 7 gph, the rpms dropped to 1000 and the oil pressure read zero. A few of those parts you talk about dropped straight into the oil pump.

Conditions were full winter at 11,000 feet on top a solid overcast. Flew 40 miles to the nearest repair facility. Was 10 pm at night. Wish we had the internet 20 year ago.

stackj · #6 09-16-09, 11:05 PM

I have never removed the fuel line either. I do find that moving the torque tube saves some four letter words for later use.

JeffAxel · #7 09-19-09, 10:45 PM

it turned out to be a sheared drive coupling, the new style. Now the question.....why did it shear?? It only had 400 hours on it. The alternator is fine, as is the engine. Can someone give me the contact info for a place that repairs these things if that is possible?? BTW only removed the battery, oil filter and the cooling hose to the alternator, took 2 hours or so to get the alternator out.