The International Cessna^® 170 Association

With all of the discussion on other threads and the fact that I need to make a few installations on customer airplanes concerning GPS installations I started to think that there must be some new guidance on GPS installations. I quit working for a major FBO on December 1st 2003. A new advisory was issued concerning GPS installations dated December 22nd 2003. AC 20-138A replaces the previous AC 20 –138 which is now void. The new AC provides guidance on determining whether an installation is a major or minor installation. I just finished reading it and if it make things no clearer than MUD don’t be surprised. I stopped down to my local avionics shop yesterday to discuss whether these installations are now considered minor or major. They are divided by paragraph 8 & 9 of the new AC. One of our local Seattle FSDO inspectors as I understand it (this is second hand info) is making things more difficult as I understand it because he believes the new AC to be in error. As the radio shop guy explained it most FSDO's now consider VFR installations to be minor and IFR installations to be major but may not require a field approval.

The new advisory circular can be viewed at http://www.airweb.faa.gov/Regulatory_an ... enFrameSet
This will take you to the portion of the FAA web sight where most Advisory circulars can be viewed on line. Most of them are PDF files so you will have to look it up when you get to the web site.

there is another Advisory Circular out that specifically addresses GPS installations. they have declared most to be minor alterations. IFR ones are a gray area, and ones for spray planes are not minor. don't have the AC # in front of me.

I didn't read your post very good. that is the one on GPS-Brian

Brian & Metal Master. this is the new AC that I spoke off changing the GPS installations.

Got to love the FSDO guys who think an AC or Reg. is in error if it differs from their opinion.

Yes this is the Advisory Circular. Chapter 9 specifically covers VFR installations. I called the local FSDO because I wanted to install an external antenna for a hand held GPS and was told it would only require a logbook entry. This link should take you directly to the 70 page AC. The other link in my previous posting will take you to a file where you can find other current AC’s which also make interesting reading if one only had the time. I have tested this and it does take me to the AC.

http://www.airweb.faa.gov/Regulatory_an ... 0-138A.pdf

When I had my IFR installation done, We have a 337 for the installation.
I redone the complete panel with breakers and other goodies.
John