|Posted: Mon Apr 15, 2019 6:40 am Post subject: The joys of a Z-14 during an charging system failure
Having just passed 1100 hours on my RV-10, I experienced my 2nd LR3C
voltage regulator failure. Like the first, this turned out to be a
non-event despite some difficulty in problem determination.
I installed a Z-14 dual bus, dual alternator, dual battery electrical
system. Specifically a B&C L-40, a B&C SD-20, (2) Odyssey PC680s, and
(2) LR3c B&C regulators. Dual mags but an electrically hungry panel
with (3) GRT EFISs and the rest of the usual kitchen sink.
The charging system failure occurred during cruise in the normal
configuration; i.e. with both buses running independently and not
linked. I first noticed the voltage slowly drop on bus1. I switched
the cross-link on and off a few times and observed the voltage climb
each time suggesting something on bus1 had failed but bus2 was running fine.
Soon the low voltage light lit so I simply switched the cross link on
and completed the 2 hour leg.
Upon landing and suspecting an LR3c failure, I ran through the problem
determination procedure per B&C. Problem was it all checked out so I
call them and they said it was probably a failed alternator. I sent it
in, they checked it out, the 1100 hour L-40 was just fine so they sent
it back for the cost of postage. I reinstalled it, reset the belt
tension and took a test flight.
All was well on the test flight so a week later I went on a 3 leg
journey to DC, Pgh and return. No problems on the first 2 legs but on
the third leg, bus 1 was out again. It was a non-event relative to
finishing the 1.5 hour leg.
I re-ran the regulator's PD procedure and step 4 failed (no voltage
drop for those following along). Since I had a previously repaired one
on the shelf, I simply swapped it out and was off and flying again.
- The LR3c can 'soft-fail' and can be suspect even if PD checks out.
- The 20amp backup alternator is capable of running my full daytime
cruising load including battery charging. It only comes up short at low
RPMs during ground ops.
- The 40amp main alternator is enough for my fully loaded RV10 and will
keep things running and charging even during low RPM ground ops (I
already knew this).
- The Z-14 provides a great deal of 'dispatch reliability'. I can
finish out a trip and get home safely in most instances even with a
failed regulator or alternator. I feel confident enough to take off
with one side failed if need be, an example being on trips to the
Bahamas as long as battery life will carry me to an airport even with a
2nd charging system failure.
- Don't mount the LR3c on the back of the firewall up under the RV10
panel where it is so *^*&^I%%$$#GD hard to get at for adjustment or
Bill "experiencing the joys of ongoing OBAM aircraft maintenance" Watson
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