231 alternator issue resolved

[jwilkins]

I've been dealing with an alternator issue for the last month. The alternator would not come on line until the engine warmed up for a few minutes, then worked fine the rest of the day. The alternator and coupling are only a couple hundred hours since overhaul.

The shop here in Prescott (Arizona Air Craftsman) made a visual inspection of the connections and checked output a couple weeks ago and the only thing we found was oil dripping on the alternator from a loose oil separator return line. Since it was working by the time I taxied in there wasn't too much else we could do. It was not the typical coupling failure as it would work fine under full load after it warmed up. The symptoms did not really fit the typical failure modes of the coupling or alternator. It was not getting any worse and was very consistent that it would work fine after warming up.

When I got back from the MAPA PPP last week I asked them to figure out what was causing this. Starting out with a cold engine they verified the field voltage was OK but no output for a few minutes, so they pulled the alternator. 

Here's the diagnosis:

Two years ago the previous owner had an A&P replace the alternator drive coupling. The coupling was installed WITHOUT the shaft bushing. Since there was no bushing he decided to crank the castle nut on hard enough to stop the drive coupling from slopping around on the alternator shaft. He also left off the cotter pin since installing it would have required backing off the nut slightly to align the holes. Bottom line; the alternator shaft and drive coupling are destroyed. The woodruff key was destroyed and the keyway in the alternator shaft was damaged from what was left of the woodruff key. When the alternator warmed up the coupling would seize on the shaft and drive the alternator even under full load.

Good news: No parts fell into the engine and the drive gear in the engine is not damaged at all.

I feel really lucky that we caught this without any engine damage. I'm not thrilled about replacing both the alternator and drive coupling, but I am really happy there was no engine damage and no parts fell off into the engine. 

The last oil analysis showed slightly high ferrous content; just enough so they recommended another analysis to check for trending. We thought this might be from the previous owner living in a humid area and not flying much. It is probably an indication of the drive coupling, woodruff key, and alternator shaft wear. 

The guys at Arizona Air Craftsman were great about continuing to diagnosis this in a logical and cost effective manner. I'm very relieved that we continued to look into this without dismissing it or waiting for it to get worse. It wasn't a big deal from an operational standpoint; it just took a couple minutes for the alternator to come on line while the engine was warming up. I could have rationalized letting it go until the annual in a couple months.

Since we didn't want to put a Kelly rebuilt alternator on, I called Dan at Lasar. He is having one rebuilt for us and it should be at the shop on Wednesday.

The point of this long rambling post is that, at least in this case, following up on a situation that is not right, but not a full failure mode yet, prevented what could have turned into major engine damage. If that castle nut had backed off, or fallen  off, the drive gear in the engine could have been damaged. This could have been a very expensive problem. It's not inexpensive to replace the drive coupling and alternator, but it sure is less than it could have been.

Thanks to the people who encouraged me to follow through and get this fixed.

Jim

 

 

 

 

 

 

[kortopates]

Great story on the importance of when something is not right, don't put it off and get to the bottom of it!

[KSMooniac]

Wow!  Thanks for the followup...this will be a great post for the archives as it does emphasize the importance of knowing your plane and chasing faults all the way to resolution when something isn't right.  Good on ya for doing so, even if it hit your checking account a bit.

FYI, I've had some discussions with a couple different Hartzell Engine Technology folks over the last few weeks (they purchased Kelly in late 2010) and they are fully aware of the Kelly reputation and quality issues.  They are actively working to correct things and expand their business, so I hope they are very successful in doing so.  Hopefully it won't be too long before we can buy their products without worry.

[jwilkins]

Quote: KSMooniac

FYI, I've had some discussions with a couple different Hartzell Engine Technology folks over the last few weeks (they purchased Kelly in late 2010) and they are fully aware of the Kelly reputation and quality issues.  They are actively working to correct things and expand their business, so I hope they are very successful in doing so.  Hopefully it won't be too long before we can buy their products without worry.

[KSMooniac]

You've got the best attitude about it, Jim.  You might consider filing a Service Difficulty Report on that previous mechanic.  If he truly did some non-conforming work like that, then it should be elevated IMO.  He was working without a service manual or neglected the instructions...either way that is not acceptable behavior for a licensed mechanic.  The best result is that it just cost you money and not worse...

[jwilkins]

Quote: KSMooniac

You've got the best attitude about it, Jim.  You might consider filing a Service Difficulty Report on that previous mechanic.  If he truly did some non-conforming work like that, then it should be elevated IMO.  He was working without a service manual or neglected the instructions...either way that is not acceptable behavior for a licensed mechanic.  The best result is that it just cost you money and not worse...

[jwilkins]

The plane is back together and working.

I didn't want to put a Kelly alternator on unless I really had no choice, so Dan at Lasar had one of his cores rebuilt at a shop he trusts. The rebuilt alternator arrived at Arizona Air Craftsman Wed afternoon; the guys got it installed, tested, and all back together on Thursday with the rebuilt coupling and alternator. It seems almost funny that the coupling rebuild cost more than the alternator.

While the cowling was off AAC tracked down a fluctuating JPI tach to a bad tach pickup, and a low #1 EGT to a broken probe clamp.

Total down time less than two weeks, and would have been quicker if I had wanted to use a Kelly rebuilt alternator. It's nice to have a good shop on my home field and people like Dan at Lasar to help with parts. Apparently I have been really lucky; I've never needed a part for the C, F , or K that Dan and Lasar could not help with.

Jim

[Txbyker]

If going with a Kelly I would make real sure they have a good quality check.  Here is a pic of my altenator installed in February and failed in April.  The left pic shows the belt deflected out almost coming off the shaft.  The right pic shows the pulley with no lockwasher and nut.  Could have been bad if I did not catch it when I did.  Plane Power was my fix.

 

 

[jwilkins]

The Kelly rebuilds are SUPPOSED to be  better now, the problem is that there are apparently a lot of units in stock which you can't tell when they were rebuilt to make a guess on quality. Not everything can be inspected without a tear down, either. Bad solder joints are not obvious from the outside.

Meanwhile, there are a lot of good rebuild shops around (like the one LASAR uses) where they can rebuild your core. Takes a little longer than getting an off-the-shelf Kelly but today you have a higher probability of getting a good unit.  Dan at Lasar had these replaced on my rebuild: front case, stator, brushes, diodes, bearing and seal. 

Arizona Air Craftsman has a shop that rebuilds alternators for them, too, with excellent service history. They did not have all the parts my core needed. 

Eventually the old stock of Kelly rebuilds will get flushed out and we'll be able to get a good rebuild off the shelf if you need one in a hurry. What I find amusing is that the direct drive coupling has a higher failure rate than the alternators, is recommended to be inspected every 500 hours, and cost more to rebuild than the alternator. I suppose the shear pin used on similr applications is bad because the shear pin coudl create debris, but it sure seems like there should be better solution than a part that has a poor service life, and costs about $2000 new and $700+ to rebuild.

Dan said when people call him to tell him they need a new direct drive alternator before it has been removed a majority of the time the alternator is OK but the drive coupling has failed.

 

 

 

 

 

[jetdriven]

The Plane Power is a Nippondenso alternator like you see on Toyotas and Hondas.   A 1960s Ford alternator can never compare favorably with that no matter who rebuilds it.  

[jwilkins]

Does Plane Power make a direct repacement for the direct drive single alternator installation on the K?

Jim

 

 

 

[jetdriven]

I don't think that they do.   I think you did the right thing, Jim, given your options.   LASAR is as good as they get.