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I had a similar problem with the B&C 60 Amp
alternator on my Glasair. After a year of trouble free operation, the
alternator started intermittently go off-line, tripping the field
breaker. My first "alternator out" event was over water at night. It took
two months to finally figure it out. It turned out to be a poor connection
of the field wire in the push-on connector on the back of the
alternator. These are the blade type connectors inside a plastic housing.
Every time I unplugged/plugged it to check the connection, it would wipe the
connection clean and it would work for a few weeks which is why it was so hard
to diagnose.
There are three blade type connectors in the
alternators receptacle housing. Only one connection is used for the field
wire. Note however that two of the wire connector tabs in the
alternator housing are internally connected together and they can both be
connected to the field wire for redundancy.
I had made two mistakes when installing the alternator
connections: 1) I used only one connector in the plastic plug housing so
the entire plug was not very stable in the alternator receptacle. 2) I
soldered the wires to the female spade connectors in the plug after crimping
them.
Soldering was a BAD idea. It annealed (softened) the
female spade connector so it didn't have a firm grip on the male counterpart in
the alternator receptacle. Utilizing only one of the connectors in the plug
allowed the entire make plug assy to wobble in the alternator female
housing. This combination resulted in a loose connection that would arc,
increase the connection resistance reducing the alternator output which the
regulator would compensate for by increasing the field
voltage/current until the field breaker would trip.
I solved the problem by installing all 3 new
connectors (crimped only) in the plug housing to stabilize the connector plug
when it is plugged into the alternator. One of the connectors wasn't connected
to any wire - it is only used to help stabilize the plug assy. I also wired
the two field connectors in the male plug together with a jumper wire for
redundancy. I don't recall which of the two of the connectors are
internally connected inside the alternator but B&C can tell you or you can
just measure with an ohmmeter. When I installed the male plug assy into
the alternator receptacle, I put a bead of silicone around the plug to further
stabilize the connector and eliminate any movement between the two. I also put a
dab of silicone around the wires where they go into the male plastic receptacle
to provide additional stability.
I've had no problems in 6 years/700 hours since
re-doing the alternator connection.
Hope this helps.
Neal Garvin
Glasair SIIS-RG N15F 820 hrs - 7
yrs
I've had an electrical problem happen for the
second time now and wanted to float it by the LML to see if its happened to
anyone else.
I have a B&C 14 volt, 60 amp alternator as well
as one of their voltage regulators. They were trouble free for about
two years until about 5 weeks ago when I went to go fly and couldn't get my
alternator to come on line. It was an uncharacteristically cold and damp
day when this happened (my plane is hangared, so it wasn't wet). After an
hour of fruitless troubleshooting, I had to cancel my flight and head for
the airlines to get where I was going.
A few days later on a nice sunny day,
I pulled off the cowl and ran through B&C's troubleshooting checklist before
calling their tech support to report that everything appeared normal. The
technician I spoke to had me do a couple of other things, then told me it should
work. I pulled the plane out, started it up and my alternator came on
normally.
I've flown several times since then
with no problems, but today when I went to go slip the surly bonds,
it happened again. Once again, it's cool, damp weather and has been
raining for several days. I don't know if that's coincidental or not, but
this time, I'm waiting for a warm dry day and will try to start up again without
doing a thing and see if it works.
I'm wondering if anyone else has had
this sort of thing happen with their B&C alternator and/or voltage regulator
or if there's something obvious I may be overlooking.
Thanks,
Skip Slater
N540ES
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