REFLECTOR:Alternator Woes.

[Scott Derrick]

Dennis,

The two that failed on my plane were flat and about 10 inches long and 
slightly curved.  I had to cut it down to about 6 inches and drill a new 
hole for the bolt that attaches it to the case. That's not where it 
cracked. Both cases it cracked where it is slotted for tension adjustment.

The junk yard bracket I got for free is angled like an "L" for strength 
and made of much harder steel. I had to grind off the end a little where 
it connects to the case, It had a locating tab on it that interfered.

You can find these cheapos at autozone, checkers, etc....

Scott

Dennis Martin wrote:
> Hi Scott,
> 
> I bought my alternator adjusting bracket out of Summit catalog.  It's 
> also chromed.  I wonder how I can tell if it's crappy metal.  My friend 
> Dennis Miller had to mill it a little to make it adjustable, so that 
> weakened it.
> 
> Thanks for sharing important information.  If it would fit, I bought a 
> super heavy duty alternator.  Aluminum case, weighs just under 8 lbs and 
> delivers 110 Amps.  It's a Denso, but beefed up by aftermarket tech 
> company.  I've forgotten the brand, but if anyone wants to know, I'll 
> get you the web site.
> 
> All the best,
> 
> Dennis Martin
> V-6 Chevy almost ready to roar
> 
> 
>> My alternator has been a constant pain in the ass since I bought the 
>> plane.
>>
>> 1.)  Bolt came out that holds the adjusting arm bracket to the case. 
>> Why?  It was not safety wired, no hole on the bolt head. It went 
>> through the prop on the way out, no major damage.
>>
>> 2.) The adjusting bracket cracked after 75 hours. This is the long 
>> bracket with the slot in it.  I replaced it with another of same make 
>> thinking it must have had a flaw.  No damage to plane.
>>
>> 3.) The new adjusting bracket cracked after 45 hours. This bracket is 
>> a universal replacement chromed bracket.  It was crap.  Poor grade of 
>> steel and chromed on top of that which weakened it even further. I 
>> questioned replacing it when I did it but didn't trust my instincts. I 
>> scavenged a junk yard for a good quality bracket. No damage to plane.
>>
>> 5.) After installing new bracket alternator still wiggled. The 
>> multiple mounting failures had caused the lower pivot mounts to wear 
>> elongation's in the mounting holes.  I reamed them out on the mount 
>> and alternator installed 7/16 shoulder bolts.
>>
>> 4.) The alternator failed.  Disassembled it and decided that this 
>> particular unit had seen 300,000 miles of service before installation 
>> on my airplane. Didn't know what the unit had come off of and my local 
>> alternator shop found a new replacement.  No damge to plane.
>>
>> 5.) One of the 7/16 shoulder bolts failed.  It was mislabeled in the 
>> store as a high alloy steel, it was garden variety.  I probably over 
>> torque'd it thinking it was a better bolt but it should never have 
>> been used in that application anyway.  It went through the prop on the 
>> way out and wholloped my Catto prop real good in 4 places(nut and 3 
>> washers).  My A&P buddy thinks it happened on the ground and the 
>> fourth whap near the tip was one of the pieces bouncing back up into 
>> the prop.  I'm replacing the  failed and remaining bolts with true 
>> 7/16 grade 8 bolts.  Also repairing prop.
>>
>> All these failures can be attributed to "Pilot Error" in my opinion.
>>
>> No safety wire on a bolt.
>> Using inferior bracket.
>> Using junk yard alternator of unknown age.
>> Using substandard hardware.
>>
>> Scott
>>
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