Jim Burns wrote:
One option is to simply get a mechanical dual tach and connect both tach
cables to the single tach but I don't know of a dual recording tach that
has dual hour meters. Anybody?

This may be a totally goofy idea, but here goes. Install the mechanical
dual tach in the panel as above. Then get two Hobbs meters and wire one
to each engine. (I know Hobbs meter time is not tach hour meter time,
but play along.) Now, since you probably don't need to look at the
Hobbs meters every couple of minutes during your flight, you can stick
them in whatever available space you have behind the panel. (An LCD
Hobbs meter is only about 1"x2"x2".) You don't have to mount them so
that the numbers are normally visible; you just have to mount them so
that the numbers are visible when you want them.

If you have enough room, you can mount them on a hinged plate or flap
that can be swung down to read the meters and then swung back up out of
the way. Maybe install a captive thumbscrew or Dzus fastener to hold
the plate in the "stowed" position. Alternatively, mount the meters
without a hinge or flap, and mount small mirrors (like a mechanic's
inspection mirror, or a dental mirror) to bring the numbers out to
where you can see them. As long as you use an even number of mirrors,
you can read the numbers. The mirror closest to your eye probably needs
to be adjustable/removable/coverable, as it might reflect sunlight into
your face in certain situations.

If you believe that there's just no kill like an overkill, mount the
meters behind the panel as above, but also include a small LED or lamp
for illumination, a cheap webcam, and a small single-board computer with
video capture, OCR software, and audio output. Wire the output into an
aux input on your headphone system and wire a pushbutton to the board;
when you push the button it says something like "left engine three six
two point five hours, right engine three six one point seven hours" into
the audio system.

Matt Roberds