REFLECTOR:Hour meter hook-up

[Wayne Lanza]

  An earlier post asked about ideas for connecting an hour (Hobbs) meter.
Here are a couple of schemes that we have used at the factory.

  We have connected the hobbs on RG aircraft to the gear system that will
turn on the meter when the gear is up. If you want to do it this way 
and you
are using the pre wired RG system, here's how to do it. Connect the (+)
terminal of the Hobbs to the +12 volt bus (a 1 Amp inline fuse is fine 
here).
Connect the (-) terminal of the Hobbs to the unused terminal on either 
the
nose or main gear 'UP' micro switch. The switch will then complete the
ground circuit when the gear is raised and the Hobbs will run.

  If you are using an electronic ignition, you can connect the Hobbs in
parallel so that it will run when the ignition is hot.

  The least used way is to use an oil pressure sensing switch that closes
with pressure that is Tee'd with the oil pressure sender. If you decide 
to
go this route, use the switch to make ground for the Hobbs. We like to
switch ground vs 12 volts in cases like this so that we aren't running a
protected +12 wire back & forth in the airplane...The pressure switch is
available from 'Spruce, find it with the Hobbs meter stuff.

  We don't use the airspeed switch because if properly adjusted it won't
activate until you're at about 90Kts (as per the factory).

Hope this helps-
Regards,
Wayne Lanza

P.S. We have been pretty busy getting the Firefly ready for Gus McLead's
        polar circumnavigation attempt. If things go as planned he might 
leave
        by this tuesday 12/20. The plane is flying again thanks to a 
generous
        donation by Lycoming of 6 new cylinders. Most mechanical issues 
are
        complete, the tanks are ready (320 additional gallons!!!) and I 
am about
        finished with the electrical mods. A quick trip to the radio 
shop for final
        avionics check out and we should be good to go. If this is of 
interest, you
        can follow his progress by going to -  http://www.GusMcLeod.com.