Mailing List lml@lancaironline.net Message #8872
From: Jeffrey Skiba <jskiba@ICOSA.NET>
Subject: More IFR GPS questions and 337 forms
Date: Mon, 12 Mar 2001 00:32:15 -0600
To: 'lancair.list@olsusa.com' <lancair.list@olsusa.com>
Cc: Kirk Hammersmith <kirkh@lancair.com>
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Okay I have been reading and re-reading here's what I have found so far in
regards to the GPS IFR "thing":

the AIM section 1-1-21 E states:
e. General Requirements

1. Authorization to conduct any GPS operation under IFR requires that:

(a) GPS navigation equipment used must be approved in accordance with the
requirements specified in Technical Standard Order (TSO) C-129, or
equivalent, and the installation must be done in accordance with Advisory
Circular AC 20-138, Airworthiness Approval of Global Positioning System
(GPS) Navigation Equipment for Use as a VFR and IFR Supplemental Navigation
System, or Advisory Circular AC 20-130A, Airworthiness Approval of
Navigation or Flight Management Systems Integrating Multiple Navigation
Sensors, or equivalent.

Now if we look up AC90-94 (Guidelines for using GPS for IFR flight)

it also states that this equipment SHOULD BE installed in accordance with AC
20-138

Okay So lets look at AC 20-138 in particular section 8:

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.

If we look at this "they" are (in my opinion) referring to T.C. aircraft not
experimental, Why you ask I think this? the TSO-C129 is a TSO for the BOX
(aka garmin 430 etc..) Which Garmin needs for their box to be approved to
install in a T.C. aircraft.

Now look at the next section " approval may also be obtained via data
approved by the FAA (responsible Flight Standards District Office) on FAA
Form 337." Also forms for a T.C. aircraft. now the really important part
"The approval for return to service must be signed by one of the entities
noted in 14 CFR part 43"

Now we look up FAA REG part 43:
it says:
Sec. 43.1  Applicability.

    (a) Except as provided in paragraph (b) of this section, this part
  prescribes rules governing the maintenance, preventive maintenance,
  rebuilding, and alteration of any--
    (1) Aircraft having a U.S. airworthiness certificate;
    (2) Foreign-registered civil aircraft used in common carriage or
carriage
  of mail under the provisions of Part 121, 127, or 135 of this chapter; and
    (3) Airframe, aircraft engines, propellers, appliances, and component
parts
  of such aircraft.
    (b) This part does not apply to any aircraft for which an experimental
  airworthiness certificate has been issued, unless a different kind of
  airworthiness certificate had previously been issued for that aircraft.

****Did everybody get that LAST section "b" : " This part does not apply to
any aircraft for which an experimental airworthiness certificate has been
issued" plus if you look the manufacture of the aircraft is acceptable to
"return to service after install" If I remember correctly We the builders
are considered the manufactures of the aircraft??


Okay, Now I do not mean to anger anybody, all this is just my opinion. I am
also trying to get this straight.




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