We can't rely on the pump's CB to trip (a fast-acting fuse i
And the non-technical assuming continuesas as happy as before. . Why
cant's we rely on the pump's CB?
>inappropriate for an inductive device). If a failed regulator were to
>supply 7 amps to the pump after the OV trips, it can take up to one hour
>to trip the recommended 5A breaker.
>
Asumming a failed regulater feeds 7 A to the pump? Or where, in which
documentation did you find this 7 A exactly? Let me guess: You assumed it.
>If the OV unit works in such a situation the remaining pump will ensure the
>engine continues to run.
>
Without OV unit, the redundancy is there, because we have a feed from
either the generator, the battery or both for ---both--- pumps. This is
original Rotax design for a fact.
Up to the next assumption, now with some added religion from pope Bob:
>after take-off. There is no guarantee that a small aircraft battery (13 -
>17Ahr) will be able to hold the battery voltage down to acceptable levels.
>If there was I am sure that Bob Nuckolls would have limited his design to
>
I am very interested to see the numbers, again. What is the chance that
a regulator, or this particular regulator will fail in the first place?
MTBF please! While assuming, why don't we assume there is some kind of
kill-dead system in the regulator itself? In a worst case scenario, what
will be the extra charge on the battery, after the pump(s), aviaonics,
lights, strobes ect have taken there share? And please don't come up
with an assumption, these things are measurable! What is the maximum
safe charging load for the battery in low and high ambients? This should
be in your batteryies' documentation. What is the time for the battery
to loose it's stabilising effect, if the regulator fails, if the fusable
link does not blow, and if it really gets the full available charge? Do
not assume please, but test it. What is the time remaining after that
before the pump(s) would fail? Anybody did this?
>just avionics protection. Total electrical failure from a single failure
>with the existing system can happen and is critical to engines with just
>
Eh? Which scenario is this again? The assuming scenario that a failing
regulator will cause a total failure?
>electrical fuel pumps. By seperating the two sources of power quickly any
>single failure is unlikely to cause engine shutdown.
>
The separation is there, in the original Rotax circuit. If i really have
to be religious, because the facts are missing, i personally prefer to
go with the opinion of the manufacturer. After all, they might have done
some real testing and have some real data available :-) And i still will
have to believe their single crankshaft will not fail me....
>it clear to those using the existing Rotax 914 electrical system that there
>is a single electrical failure that can cause engine shutdown. If we are
>
No, there is not, not until somebody turns up facts. There are
assumptions. Lots of them.
>input. How the individual goes about this is up to them but the expertise of
>Bob Nuckolls sounds like a good starting point to me.
>
What about the expertise of the manufacurer?
Jos Okhuijsen
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