Imperial vs. US gallons.

[Archaeopteryx]

I seem to have found a problem with my Comanche's fuel calculations. The Payload and Fuel Manager offers the choice between Imperial and Metric. Unfortunately, it is not using Imperial gallons, it is using US gallons which are 20% smaller. As the manual says on p.53 main tanks are 60 US gals., which is about 360lbs. 60 Imperial gallons would be 432lbs. This doesn't cause a problem when flying the basic plane, because the pilot's notes pop-up and the fuel flow gauge all use the same gallons, but when the Flight1 GTN750 is installed the fuel planning utility gets wrong info. It seems to believe the aircraft is actually using Imperial gallons, so it converts the GPH figure to US gallons, thus basing all its calculations on a fuel flow 20% too high.
For example: My Comanche's Payload and Fuel Manager was showing 57gals, 342lbs. Pilot's Notes and the fuel flow gauge showed 3.5gals/13 liters per hour. GTN750 showed fuel flow as 5.1gals/hour, which would only be correct if it was converting UK to US gallons.

I've looked through me other A2A aircraft manuals and this seems to be the same for all of them.

Bob Millar

[Lewis - A2A]

Hello,

we use our own advanced payload simulation which will mean systems using the platforms default simplified system will not work correctly.

thanks,
Lewis