EFIS D10 heading errors

beechman35

New Member
Joined
Apr 16, 2007
Messages
4
Hi,
I really need some serious technical assistance with this one. We recently installed a D10 system with remote mag sensor and temp probe as a backup in a 1967 Cessna 210. We installed the mag sensor just aft of the main gear wheel wells with the temp probe under the belly about 4 feet aft of the gear bay. We carried out the heading system cal and all appeared ok and errors within limits. We then flew the aircraft and saw heading errors of up to 30 degrees. We worked it out that the main gear legs were magnetised for whatever reason, so, pulled the legs, demagnetised them, test flew again. No difference. Still 30 degree errors. We then moved the sensor right down the tail making sure we were clear of beacon wiring and nav light wiring. Ground cal looked good, still errors in the air. We then moved the sensor out into the R/H wing tip area, about 3 feet inboard of the tip and moved the temp sensor to under the R/H wing to fuse fairing. Ground cal good, errors of up to 20 degrees airbourne, AND indicated temperature errors which change in magnitude and direction on a day by day basis, but mostly positive, so this also upsets the TAS indication. All connections have been checked for security, looms checked for any damage, even rewired the sensor back to the D10 and the temp probe, still no joy.
PLEASE...... I need any ideas as to whats going on. My customer is going to kill me if we cant fix it and as you could imagine, I am sick of the ongoing cost to us for installing it and moving stuff to try and fix.
 

dynonsupport

Dynon Technical Support
Staff member
Joined
Mar 23, 2005
Messages
13,226
The first thing we always ask in these situations:

Are you sure the unit is using the remote compass? The easy way to check is to put something magnetic near the EFIS. If the heading moves, it's not using the remote compass.

Also, is this a D10 or a D10A? Does the compass match as well? The compass needs to be an EDC-D10 for a D10, and a EDC-D10A for a D10A.
 

beechman35

New Member
Joined
Apr 16, 2007
Messages
4
Hi again,
The system is a D10A and we checked what you asked. There is no deviation when a magnet is moved near the panel mounted unit, but when placed near the remote sensor, the compass card moves accordingly. Also, for a further test, the ambient temperature did match the OAT gauge at +17 C and increased when the probe was held for a minute or so. All appers to be normal as long as the aircraft is on the ground. It only appears to be erratic when in flight. Has there been any reports of vibration errors with the remote sensor?
Any help would be great.
Thanks again
 

fabjab

New Member
Joined
Apr 4, 2005
Messages
100
Location
George, South Africa
I can only comment on the OAT location based on my experience. I originally had the OAT probe installed under the tail section, just forward of the horizontal stabiliser. The effect of the exhaust gasses even about 4m behind the exhausts was at least 5C. This also changes with the relative airflow (AoA, sideslip).

I ended up moving the probe to the sidewall of the cabin, in the shade of the wing (high wing) and have had consistant and correct temperatures since then.

Based on a previous question to Dynon, they do not correct for frictional heating of the probe, so maybe in the wingroot fairing would be a good idea, although this would lead to inflated readings while on the ground (and also inflated density alt display)

Blue skies,

Carl.
 

beechman35

New Member
Joined
Apr 16, 2007
Messages
4
Thanks Carl,
Yes, we thought the same with the elevated OAT readings when we had the probe in the belly, thats one of the reasons why we went for the wing root. The errors we get in flight can be anything up to +20C . Last flight we were at 9500 feet and were indicating +29C and the reading was flickering. I still think its down to a vibration problem in the remote Mag unit.....
Over to all reading..
Thanks again
Rob
 

dynonsupport

Dynon Technical Support
Staff member
Joined
Mar 23, 2005
Messages
13,226
We've never seen vibration issues with the EDC.

Do you have the panel tilt set on your EFIS? Changing this will mess up your cal, and it needs to be set before you cal the unit.

Also do you have the tilt of the EDC the same as the tilt of the EFIS? If not correct, this will cause serious issues as the attitude changes.
 

beechman35

New Member
Joined
Apr 16, 2007
Messages
4
Hi,
Angles are the same between the units. When on the ground, we are sitting slightly tail low compared to in flight and this may have some bearing on the errors noted on the compass system, but does not answer the errors we see intermittently on the temperature. Have checked the system again this morning and the temp looks fine. We are doing an engine change at the moment and will be doing runs soon, so will look for any errors again then and report further.
thanks for the input so far
regards
Rob
 
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