REFLECTOR: Engine Monitors

[mhadley1@juno.com (Martin A Hadley)]

I have been asked for my opinion of a particular model of engine monitor.
I would like to address my remarks to all of the "self-contained" engine
monitor systems, i.e. Audio Visual AV-10, Rocky Mountain Instruments
microMONITOR, Vision Micro Systems VM-800 and 1000 series systems, and
similar systems. I know that at least one of these systems has a long and
outstanding track record for time between failure. I think these types of
systems are the greatest thing to happen in the aviation market, right up
to the point where they fail in flight. And they do fail. (Murphy's Law
says it'll happen in IFR conditions.) If the sole flat panel display on
any of these units goes out, that equals no display of anything that was
displayed on the unit before the failure. RPM, Man. Press, oil
press/temp, fuel press/temp/flow, EGT, CHT, volts, amps, all of it! If
the power to the central 'brains' of these things fails for any reason,
the otherwise functional display becomes blank.

My opinion?

If you install one of these systems, at least install a totally
independent backup oil pressure gauge. In the event of a system failure,
you can hear if the engine is running, maybe not how fast, but you will
know if you have rpm. If the engine is running, it surely has fuel. But
if you are loosing or have lost oil pressure, you won't know that until
the engine starts to knock. At least armed with real time information
that  the engine is running, fuel in the tanks, and you have good oil
pressure, plus the fact that you have experienced no major engine
problems during the trip or since you last made a repair to the engine,
should give you some peace of mind until you can find a place to safely
land, remove the failed system, and send it back to the vendor to get it
repaired. 

I'd just as soon continue on my trip with a failed single gauge in my
engine instrument cluster. That is why I like VDO, JPI, Westach,
Mitchell, etc. I guess it is that "all of my eggs in one basket"
syndrome.  

BTW...Available from AC Spruce is a small Mitchell oil pressure gauge
that I have installed in several panels using the above mentioned self
contained systems. It is 1.5 inches square and costs under $200.

Safe and Speedy Construction!

Martin 

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