On Thu, 18 Dec 2003 18:06:12 -0500, Gene Kearns
wrote:

On Thu, 18 Dec 2003 22:44:22 GMT, Newps wrote:



Gene Kearns wrote:

Frankly, I don't think anything about a transponder rises to the level
of a Major Alteration... ditto radios, intercoms, etc.

A panel mount GPS is a major alteration. The back of the 337 is an
unreadable mess only a government agency could come up with. And mine
was a slide in replacement for a Loran.

W&B issues and possibly IFR issues aside, this might have been,
arguably, preventive maintenance that you could have accomplished,
yourself. FAR Part 43, Appendix A(31)...

After a telephone call to AOPA, I find that I'm not the only one that
has trouble with this. The best they could suggest is that an
installation requiring more or less amperage draw than the last
installation has been considered by some FSDOs a "change to the basic
design of the ...electrical...system. I say, "bovine scatology" and
I'm 99.99% sure my avionics PMI would agree...... but then each FSDO
is its own domain...

Take a look at:

http://www1.faa.gov/asd/internationa...C/AC20-138.pdf

7. AIRWORTHINESS CRITERIA FOR GPS INSTALLATIONS USED AS A SUPPLEMENTAL
NAVIGATION SYSTEM LIMITED TO VISUAL FLIGHT RULES (VFR) ONLY.
a. Application Process. Operators wishing to obtain approval of Class A() GPS equipment limited
to VFR use only may do so via the type certificate (TC), supplemental type certificate (STC), or, for equipment
previously approved via the TC or STC process, data approved by the FAA (responsible Flight Standards
District Office) on FAA Form 337, Major Repair and Alteration. The approval for return to service must be
signed by one of the entities noted in 14 CFR part 43; i.e., repair station, manufacturer, holder of an inspection
authorization, etc.

8. AIRWORTHINESS CRITERIA FOR GPS INSTALLATIONS USED AS A SUPPLEMENTAL
NAVIGATION SYSTEM UNDER INSTRUMENT FLIGHT RULES (IFR).
a. Application Process. Operators wishing to obtain approval of Class A() GPS equipment for IFR
operations may do so via the type certificate (TC) or supplemental type certificate (STC) process. For
equipment produced under TSO-C129 authorization that has previously obtained initial installation approval
via the TC or STC process, approval may also be obtained via data approved by the FAA (responsible Flight
Standards District Office) on FAA Form 337. The approval for return to service must be signed by one of the
entities noted in 14 CFR part 43; i.e., repair station, manufacturer, holder of an inspection authorization, etc.

I wouldn't say it is the only means of "approving" a GPS install, but
it's definitely the one a FSDO is going to wave in your face.

Regards;

TC