On Wed, 19 Nov 2003 14:00:26 -0500, Andrew Gideon
wrote:

Ron Natalie wrote:

An IA must sign off the 337, which is required of any major alteration.
An STC
provides authority to make the major alteration. A minor alteration
requires neither a 337 nor an STC.

It sounds from the above like an STC is required before any major alteration
because it "provides authority to make the major alteration". Is that
right?

A lot seems to hinge on the distinction between "major" and "minor"
alterations. What is the difference? Given a particular change (ie.
replacing a panel overlay, or adding instrument lights), how does one know
into which category the change falls?

- Andrew

What is *required* before a major alteration is approved data. How
you obtain that can vary, STC, Field Approval, etc....

Well, technically, you don't really need it until the work is
inspected.......BUT..... Trust me, though, you want the approved data
*before* beginning *any* work.