What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

Annuals, broken parts, and assistance request

airguy

Unrepentant fanboy
Sponsor
I'm currently in the process of conducting my annual inspection and installing the SDS EM5 engine management hardware, and associated with that I needed to pull the flywheel to drill and tap it for trigger magnets. To pull the flywheel I need to loosen the alternator belt first, and as soon as I took a look at the alternator, before I even loosened the first bolt I knew something wasn't right. The belt angle was wrong and the alternator was obviously not hanging correctly, and as soon as I started to loosen the first bolt the problem was obvious.

opq.jpg


And the bolt that was holding it also caught some wear, it was obviously working for some time. 560 hours since new, 193 hours since last annual, and I know I had the alternator off for that annual.

opC.jpg


This is the short bracket and bolt that holds the Plane Power 60-amp alternator to the Skytech starter, I'll obviously need to order new examples of each, and thus the question here. Can anyone tell me the appropriate part numbers for these? I put in a question on the Plane Power website but do not have a response yet.

Sidenote - this is why we do GOOD annuals, and not just a paper exercise! If you don't put a wrench on the part before putting a checkmark on the paper, you didn't do anything worth doing.
 
Last edited:
I just googled 'plane power installation sheet' and came up to a page listing all the pdf sheets. There are part#s on them.
& B&C is another option...
 
Last edited:
Do yourself a favor and get a B&C now.

I recognize that there is a level of heartburn that exists with several folks with Plane Power - but this is a bracket problem, not an alternator problem. Are you saying PP makes low-quality mounting hardware?
 
It took a bit of Google-Fu and about 30 minutes online with a parts distributor but I got the part properly identified and ordered - only $12 plus shipping, a rarity in the aviation parts world that truly surprised me.

Looking at the picture,I’d think the bolt wasn’t tight. Was there a tube spacer between the case bracket forks?

No, this bolts directly to the right hand side of the alternator when viewed from the front of the airplane, and extends from there to the left hand side of the starter, the "A" mounting tab on the Skytech 149NL series. There are no spacers other than a few washers. The broken piece is the starter end of the bracket.
 
I've seen this type of wear caused by the bolt not being tight enough. The reason it was not tight enough was the use of a drilled bolt with a castellated nut. Torquing properly is a chore because often you could not get to the next castellation point without being too tight and one back ended up too loose. My solution is use a non drilled bolt and a high temperature self locking nut.
 
Check carefully when installing the new bracket that it sits flat at each end, & if some washers might be needed to make it sit flat. Not sitting flat would cause bolts to not torque properly and create spot stress points that could break off the end.

I'd also suggest installing a new belt during reassembly.
 
Part #'s

Bolt -- AN7-42A
Bracket -- 10-1002

and for future reference, you need 450 - 500 inch lbs. of torque on that bolt...
 
Without implying anything, can I ask why you had the alternator off last annual? This seems like one of those MIFs that Mike Busch talks about so much that we need to be extra-careful to avoid when doing MX?
 
Isn't the solution for a castellated nut that won't "line up" a different washer stack?

Maybe even a custom thickness washer?

FWIW
 
Without implying anything, can I ask why you had the alternator off last annual? This seems like one of those MIFs that Mike Busch talks about so much that we need to be extra-careful to avoid when doing MX?


If I remember correctly, I didn't actually pull it off - I loosened it to remove the belt to look for wear on the belt, and spin the pulley to listen to the bearings and make sure all was well.

It's entirely possible I didn't get enough torque on it when it went back together. Most of my major mistakes require a divorce attorney, this one just needed a new bracket.
 
If I remember correctly, I didn't actually pull it off - I loosened it to remove the belt to look for wear on the belt, and spin the pulley to listen to the bearings and make sure all was well.

It's entirely possible I didn't get enough torque on it when it went back together. Most of my major mistakes require a divorce attorney, this one just needed a new bracket.

That's not a bad idea (checking the belt and bearings, not the divorce :)), but I wonder if there's a way to do it without loosening the alternator bracket...from way way WAY back in my youth, I recall that when working on autos one could put a belt on or take it off by putting a screwdriver or some other pry bar underneath the belt and rotating the alternator or whatever, to "roll" the belt on or off...might something like that technique work here? Dunno, maybe a bad idea in an aircraft installation, but it worked on the buckets of bolts we had to keep running to get to classes in college :).
 
Ditch Plane Power

and get a B&C.

I had something similar (wear issues) happen with my first Plane Power. So I replaced it with a new one.

I didn't blame Plane Power for incorrect torque.

But, the second one lasted only 200 hours and failed due to only charging at 1/2 capacity. I'm now flying on a Plane Power with internal parts from a 9 year old Plane Power (better quality then) and a case from a 200 hour Plane Power.

Condition inspection soon.. B&C for me!
 
Back
Top