[gladiator68]

Hi Guys,

I am planning on mounting my ADHRS box from GRT (only 3 wires) behind the baggage area attached to the F-787 stiffner web at top of aft fuse, behind F-708 bulkhead. It is about 16 in from harness cables. I mounted on wing tip it would be about as close to the more massive aileron counterweight. This saves me from running another conduit in wing separate from the pos/nav/landing light wiring. Anyone see any issues with this position?

Thanks.

 

[skirting_virga]

FWIW, I have a Sport EX which has integrated/internal ADAHRS. I pushed one of the buttons extra hard while on autopilot recently. The flex of the panel made it think I pitched up, and the autopilot pitched down. It's sensitive.

I've heard of people mounting it to the sub panel with good results. I'm sure your location is probably also viable.

 

[Canadian_JOY]

Hi Guys,

I am planning on mounting my ADHRS box from GRT (only 3 wires) behind the baggage area attached to the F-787 stiffner web at top of aft fuse, behind F-708 bulkhead. It is about 16 in from harness cables. I mounted on wing tip it would be about as close to the more massive aileron counterweight. This saves me from running another conduit in wing separate from the pos/nav/landing light wiring. Anyone see any issues with this position?

Thanks.

Ummm... I think you may mean "magnetometer" - the newer GRT digital magnetometers are a 3 wire connection, power, ground and RS232 out to the EFIS display unit.

 

[Scott Hersha]

Ummm... I think you may mean "magnetometer" - the newer GRT digital magnetometers are a 3 wire connection, power, ground and RS232 out to the EFIS display unit.

Agree. I’m not aware of an external GRT AHRS unit. On two of my builds, the wingtip location for the magnetometer (if that’s what you’re referring to) has worked well. The magnetometer is far enough from the aileron counterweight to not cause a problem. All wires to the wingtip run through the same conduit.

 

[Dugaru]

Agree. I’m not aware of an external GRT AHRS unit. On two of my builds, the wingtip location for the magnetometer (if that’s what you’re referring to) has worked well. The magnetometer is far enough from the aileron counterweight to not cause a problem. All wires to the wingtip run through the same conduit.

Just as a data point, my Horizon EX actually has an external AHRS because it was upgraded from a WS. And the airplane was basically built around that AHRS location as if it were the pharaoh’s tomb. I think you’re right that no current units have an external one.

 

[lr172]

Ummm... I think you may mean "magnetometer" - the newer GRT digital magnetometers are a 3 wire connection, power, ground and RS232 out to the EFIS display unit.

He may be installing an older model. From the HXr and back, they used a standalone ADHRS.

Mine is mounted on one of the longitudinal ribs going to the firewall. Very stable there.

 

[skirting_virga]

He may be installing an older model. From the HXr and back, they used a standalone ADHRS.

I was wondering the same thing...

I can't speak to the appropriateness of the intended location but my experience has been that rigidity is of the highest importance. Walt recently mentioned subpanel mounting for Garmin ADAHRS and that seems ideal to me, but I'm also aware that some people like to mount closer to the static ports.

 

[Ironflight]

I agree with the folks that think the OP is talking about his Magnetometer - and the mid-fuselage location has always worked for me. ADAHRS really should ideally be as close to the center of rotation (in all axes) of the airplane as it can be (to avoid translation effects in rotational motion), but it is more important to mount it to something very rigid. The sub-panel is good (if it’s stiff enough). In my -8, thje GRT ADAHRS are mounted to a platform I built between the sub-panel and the main panel support - very rigid.

I like fuselage magnetometers over wingtip mounts becasue they are easier to wire and test in the shop (before wings are installed). But once the airplane is built, it makes no difference, and the wingtip position works fine for most folks.