>
> I agree we want guaranteed and/or redundant power supply to at least one
914 fuel pump, but I can't find actual data to class the reg as very poor,
though. There are anecdotal reports, but FAA's Service Difficulty
Reports -- as as voluntary program it's a database of anecdotal reports
also -- shows no alternator/regulator failures. It does cite other
problems, many familiar in Rotax service bulletins.
>
Hi all,
I've directly heard of several such failures. I recently took some pictures
of the internals of a failed rectifier/regulator. With a fellow pilot and
electric engineering researcher, we are performing some tests on a Rotax
alternator and rectifier/regulator.
Below is a copy of a message on the Aeroelectric List some weeks ago. The
subject was Rotax rectifier/regulator reliability.
Regards,
Gilles
>What is the problem with the original rectifier/regulator from Rotax?
The standard rectifier regulator supplied with Rotax 912/914
engines is, I believe, made by Ducati. Ducati makes a whole
raft of ignition and power generation products for small engines
where the largest markets are for all manner of recreational
vehicles . . . a tiny portion of which is aircraft.
If you do a websearch on ducati "voltage regulator" and rotax
you get a bunch of hits. Far too many of those posted articles
talk about making the Ducati part last with most
of the "fixes" going to keeping the part cool.
My experience with Ducati parts suggests poor attention to
design with respect to keeping internal parts of the regulator
within their best operating temperature range. B&C's "heavy
duty" regulator was nothing more that the standard circuit
with robust, well heat-sinked parts.
Do some research on the web and I think you'll get a sense
of how much trouble folks are having with what should be
a no-brainer.
It would be a step forward to simply improve the thermal
design of the current design. If I understand what Gilles'
friend is attempting, we should be able to replace high-voltage-
drop rectifiers with low-voltage-drop power field effect
transistors. It's a much more complicated design but promises
to offer much higher efficiency -AND- ultimately higher current
carrying capacity. 18-20A is pushing the practical limits for
the current design.
Bob . . .
|