Vertical speed

[David Reel(Guest)]

Does anyone know why my vertical speed would indicate a 250 fpm rate of climb while flying straight and level according to the altimiter? I have a Dynon D10 installed in an RV8A and the backup altimeter and airspeed instruments agree quite closely with the D10.

Dave Reel

 

[dynonsupport]

Not sure I fully understand what you are seeing. It sounds like your Dynon and mechanical airspeed indicator and altimeter agree and are both correct. Is that right? Is it the EFIS which is showing a non-0 vertical speed? When it shows vertical speed, is the altitude actually changing at all? Finally, do you have a mechanical VSI?

 

[dynonsupport]

If you are talking about a mechanical VSI, every one I have ever seen has an adjustment knob that allows you to "zero" the VSI. It's usually behind one of the mounting screw holes. If it's reading 250 in level flight, it should read 250 on the ground as well, so you can just zero it there.

 

[David Reel(Guest)]

I don't have any vertical speed info except the D10. At the time of the reading, the altimeter was not showing any marked change. I think I'd notice 250 fpm on the altimeter, but.... On the ground, the VS reading is 0 on the D10. I'll be checking this on my next flight & will let you know the results.

Dave Reel - RV8A

 

[dynonsupport]

250 ft/min is only 4 feet per second, so you'd have to look at the screen for about 3 seconds to even see a 10 ft change. The VSI and altimiter come from the same sensor in the EFIS, so if your altitude is right, the VSI should be right.

The only other thing I can think of to check is the clock in the EFIS. If it's running fast for some reason, then VSI will be calculated high. Check the clock over an hour or so and make sure it is within a few seconds.