Is a Compass Correction card required equipment?

C5Engineer · #1 09-13-2009, 11:41 AM

I just rebuilt a non RV experimental from the ground up and I had my first conditional yesterday. I had a question I was hoping you guys could help me out with. It has a compass in it that has a flat face, similar to a gyro only it's just a mag compass that can be adjusted. The A&P checked that it swung. He also told me I needed to have a correction card for it. According to FAR's that I read a compass is not even required equipment for an Experimental that is Day VFR only BUT the operating limitations can state otherwise as always. Because of some circumstances that is a whole another story I have to re apply for my AW cert and I'm meeting with a DAR on Wed for that process. I want it to go as smoothly as possible. My field DOES NOT have a compass rose so doing up a card would kind of be a pain that I don't want to mess with if I don't have to.

Any advice on the subject so make my DAR visit go as smoothly as possible?

Quick shot of my panel to show the compass. It's in the center on top of the glare shield

Vlad · #2 09-13-2009, 11:50 AM

Joey,
Welcome to RV World! Check this thread http://www.vansairforce.com/communit...rd+requirement you may find it useful.

C5Engineer · #3 09-13-2009, 12:57 PM

Thanks for the link I should have searched..I'm a moderator on a large forum and know better but I only have basically one day left to do any final tweaking on my plane before the DAR comes out so I'm a getting a bit ancy.....i.e. lazy for looking for info

After reading that thread and several others on other forums it's still grey area. I think I'll at least print one out and have it available in case he wants to see it but I'm not going to stress over having one posted and filled out.

On a side note..great forum. I've always been fascinated with RV's but unfortunately WAY out of my price range. I'm an enlisted guy in the Airforce and play money is tight sometimes. I rescued an Avid Flyer out of a barn and have been slowly rebuilding it over the past 4 years. My meeting with the DAR wed is my last step in having it legally ready to fly. What a great feeling of accomplishment!

Here's a shot of it on her first taxi in nearly 15 years

pierre smith · #4 09-13-2009, 02:20 PM

...you can taxi a little bit on the heading you want and then look at what the compass indicates and use the GPS as your compass rose. It's what I did for my Air Tractor's correction card.

Regards,

Ironflight · #5 09-13-2009, 03:36 PM

When I had my DAR inspection, I saw the face of my DAR light up when he saw the Compass Correction card. "Wow - you even have one! Most people don't, and if you have a compass, you should!" When I sheepishly pointed out that it was still blank, his response was "that's OK, it just needs a card - i don't know if it's accurate!"

And neither will anyone else.....I'd do Pierre's GPS line to establish north, and fill out your card.

Paul

Sam Buchanan · #6 09-13-2009, 04:29 PM

Quote:

Originally Posted by C5Engineer

Because of some circumstances that is a whole another story I have to re apply for my AW cert and I'm meeting with a DAR on Wed for that process. I want it to go as smoothly as possible. My field DOES NOT have a compass rose so doing up a card would kind of be a pain that I don't want to mess with if I don't have to.

Any advice on the subject so make my DAR visit go as smoothly as possible?

Put the card in the plane and fill in some numbers according to best estimation (use a Boy Scout compass as a rose). How will the DAR know how accurately the card reflects the actual performance of the compass?

If you are day VFR and have a GPS you will most likely never use the vertical card compass anyway.

Enjoy your new plane!

L.Adamson · #7 09-13-2009, 04:37 PM

Quote:

Originally Posted by Sam Buchanan

If you are day VFR and have a GPS you will most likely never use the vertical card compass anyway.

I use it all the time! The plane is on GPS controlled auto-pilot, and I use the compass to adjust my constantly precessing six pac directional gyro. Just something to do...

L.Adamson --- RV6A

Kevin Horton · #8 09-13-2009, 05:07 PM

Quote:

Originally Posted by pierre smith

...you can taxi a little bit on the heading you want and then look at what the compass indicates and use the GPS as your compass rose. It's what I did for my Air Tractor's correction card.

This procedure will work in some places, but it won't work everywhere. The GPS determines true track and current position. It then looks up the predicted magnetic variation for the current position and converts true track to magnetic track. The problem is that the GPS's internal model of magnetic variation has a fairly coarse resolution. If there are any local magnetic anomalies they won't be accounted for in the predicted magnetic variation.

Here is an example of the problem - In my day job, I see some of the in-service issues reported by operators of some aircraft types. One popular regional jet has had many reports of compass anomalies when the crew checks the heading on the runway at some airports. This aircraft has a fairly low wing, with the flux valves in the wing tips, and an Attitude and Heading Reference System that responds quite quickly to changes in the local magnetic lines of flux. It turns out that there is a lot of scrap steel in the fill that was placed below many ramps and runways, causing local magnetic anomalies, which is affecting the accuracy of the compass system of this regional jet at some airports. Other aircraft types, with flux valves higher off the ground, aren't affected nearly as much.

noelf · #9 09-13-2009, 05:48 PM

...and my take-away was the inclusion of the compass correction card was at the "whim" of whatever DAR or FAA Airworthiness Inspector you happen to get. If the card is not present, then you may (or may not) have an issue with the inspector. If it is there, then you are covered. It does not need to be filled out, just present.

C5Engineer · #10 09-13-2009, 06:37 PM

Great discussion. I got tired of all the speculation so I just called the DAR that will be inspecting my plane and asked him. He said do you know the equipment requirements for an experimental? I said yes I do I looked them up and he said then you know you don't even need a compass let alone a card. Guess that answers it at least for me. As you guys know every A&P and every DAR is different. Thanks for help.