How about connecting it to the radio power line?
So that is then a radio hobbs in fact.
We normally always start the engine first and then a while after switch radios
on.
Radios off and then engine quit vice versa.
That is a rule for radio safe.
During engine tests and trial runs we do not wanna maybe count engine hours at
all.
When there is an intention to fly, radios are always on I assume.
Bad side: during radio tests only you count also engine hours.
But, how often you do make radio tests only (w/o engine running)?
In my case in the hobbsmeter there are 202,9 hours logged and in the logbook
there
are 154,1 pure flight hrs.
The difference between those numbers are mostly because taxiing and those
exciting
early taxi tests (and radio on!).
Other possibilities: hobbs is on when gyros and/or FMS are on.
If I had liked to count only pure flight hours I would have connected it to the
main gears retracted position micro switch. In the other hand; at least GPS and
autopilot (Trio) are logging pure flight hours so that was not an option for
me.
That is real flying when the gear(s) is(are) up, is not it? Unfortunately only
possible for monos...;)
To service my engine I use flight hours (with high revs) - not engine hours.
That
is a fair play!
Raimo from Finland
OH-XRT grounded for an annual service and some extra which will make it even
heavier
again.
----- Original Message -----
From: "Frans Veldman" <frans@privatepilots.nl>
Sent: Tuesday, January 19, 2010 4:03 AM
Subject: Re: Europa-List: Re: Oil Pressure Switch for engine hourmeter
>
> On 01/18/2010 09:25 PM, Rowland Carson wrote:
>
> > One end of the warning lamp is connected to the C terminal of the
> > regulator (also commoned with R & +B) so that better be at 12V when the
> > donkey is running. The other side of the lamp goes to the L terminal
> > which presumably is normally floating, open circuit (or even +12V?) but
> > drops to 0V when things go pear-shaped.
>
> Well, you don't have to connect the lamp to the C terminal, any 12V
> connection would be fine. I have mine connected behind the master
> switch, and behind the panel fuse. The only wire going to the alternator
> controller is the L wire, which doesn't need a fuse at all.
>
> About the hobbs: Connect the + of the hobbs to the L wire (either end
> would be fine, but the end near the bulb would be practical). Connect
> the - of the hobbs to ground.
> This will cause the hobbs to run as soon as the master switch is on,
> unless the bulb lights up. So, it will effectively count the engine hours.
>
> That's really all there is to it. No need for oil pressure switches or
> other gadgets.
>
> > The diagram calls out a 30A slo-blo fuse to protect the 12AWG wire
> > leaving the C, R, +B terminals. However, there is NO protection for the
> > 20AWG wire leaving the same spot and going through the firewall to the
> > alternator warning lamp.
>
> No, because you are supposed to connect it behind the fuse. The 12AWG
> wire is connected to the C terminal, so instead of connecting the lamp
> to the C terminal directly, you could as well use the other end of the
> 12AWG wire. 12 Volts is 12 Volts after all. ;-) In fact, any 12 V line
> would serve the same purpose.
> You should indeed not connect any unfused wire to the C,R or B terminals!
>
> Hope this is clear now.
>
> Frans
>
>
>
>
>
>
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