GI275 question

[traumamed]

...but I'm concerned that the pitch down may suggest that I have some kind of airplane rigging problem, or the GI 275 is out of calibraion.

Another vote that it is much more likely the GI-275 just needs to be recalibrated/have the offset readjusted. A true aerodynamic problem that requires you to be 5° nose down in trimmed level flight would manifest other aircraft control issues that should be pretty obvious, not to mention that your airspeeds should be quite a bit off from expected/published numbers.

 

[Ryan Klems]

Sorry for the resurrection of this thread, but it still might be relevant, especially to my issue.

First, yes, I understand that pitch relative to the horizon changes based on airspeed. In fact, these pitch settings are used for various phases of instrument flight.

I recently installed several GI 275s in my 182. When the airplane is trimmed for cruise level flight, the nose shows about 5 degrees below the horizon while VSI shows 0. I can easily rationalize pitch up indications, but I'm concerned that the pitch down may suggest that I have some kind of airplane rigging problem, or the GI 275 is out of calibraion.

This does seem a bit off. If you happened to have a digital inclinometer (or access to one), I'd be curious to check the reading across your level points (not sure what your particular 182 is, but later ones have 2 leveling screws forward of the horizontal stab on the left side of the aircraft, earlier ones use the top of the empennage between the rear window and the vertical fin) and then compare that to what your GI-275s are showing. This would be a quick 5m check to tell you if the GI-275 is grossly miscalibrated.

 

[write-stuff]

This does seem a bit off. If you happened to have a digital inclinometer (or access to one), I'd be curious to check the reading across your level points (not sure what your particular 182 is, but later ones have 2 leveling screws forward of the horizontal stab on the left side of the aircraft, earlier ones use the top of the empennage between the rear window and the vertical fin) and then compare that to what your GI-275s are showing.

Appreciate the comment, Ryan. Parked on level ground, the 275 shows a 5 degree pitch up. In level cruise flight (VSI=0) the 275 shows 5 degrees pitch down. Seems to me to be a pretty huge difference. I have a call in to Garmin support now. We'll see what they say.

 

[Hang 4]

Appreciate the comment, Ryan. Parked on level ground, the 275 shows a 5 degree pitch up. In level cruise flight (VSI=0) the 275 shows 5 degrees pitch down. Seems to me to be a pretty huge difference. I have a call in to Garmin support now. We'll see what they say.

Think that might be your issue right there. Level ground is not the standard, level per the service manual is. Do what Ryan suggests, check level at the level points with a level. (did I say level enough?)

 

[write-stuff]

Think that might be your issue right there. Level ground is not the standard, level per the service manual is. Do what Ryan suggests, check level at the level points with a level. (did I say level enough?)

I can understand the 5 degrees up when parked, but yes, I need to confirm that the shop used the proper level points.

UPDATE: I spoke with a Garmin tech on the phone. He suspected miscalibration as the cause. Back to the shop for investigation.

 

[Mike Gagnon]

Here's the picture:

That looks like 2.5 degrees low, not 5. Still unexpected offset from the horizon I assume - I just wanted to point out that the magnitude isn’t as bad as being said in the text.


Sent from my iPhone using Tapatalk

 

[write-stuff]

That looks like 2.5 degrees low, not 5. Still unexpected offset from the horizon I assume - I just wanted to point out that the magnitude isn’t as bad as being said in the text.

Good catch, Mike. Much appreciated.