Glide computer in certified glider

On Saturday, May 12, 2018 at 3:10:57 PM UTC-7, 2G wrote:
On Thursday, May 10, 2018 at 11:35:08 PM UTC-7, Bob Kuykendall wrote:
On Thursday, May 10, 2018 at 7:48:12 PM UTC-7, 2G wrote:
So, you think I am full of ****...

I wouldn't have put it in so few words.

If you do call the FAA for guidance, they will likely refer you Advisory Circular AC 43-210A (https://www.faa.gov/documentLibrary/...AC_43-210A.pdf) “Standardized Procedures for Obtaining Approval of Data Used in the Performance of Major Repairs and Major Alterations.� This covers what constitutes a minor repair:

“3.2.2 Determine the Repair or Alteration Classification. Determine if the repair/alteration is a minor change in type design (as defined in 14 CFR part 21, § 21.93) to the product’s type design; and if so, is it a major or a minor repair/alteration. To determine if a repair/alteration is major or minor, refer to part 43 appendix A. Figure 3-2, Determination of Major or Minor Alteration or Repair, is a flowchart of the field approval evaluation process based on part 43 appendix A.�

The regulation referenced, 14 CFR part 21, § 21.93, explicitly defines what constitutes a minor repair (https://www.law.cornell.edu/cfr/text/14/21.93):

"(a) In addition to changes in type design specified in paragraph (b) of this section, changes in type design are classified as minor and major. A “minor change� is one that has no appreciable effect on the weight, balance, structural strength, reliability, operational characteristics, or other characteristics affecting the airworthiness of the product. All other changes are “major changes� (except as provided in paragraph (b) of this section)."

The addition of instrument not required for certification constitutes a minor alteration (unless it affects the performance of required instrumentation) and meets the above criteria. An FAA airframe inspector are available to answer any questions concerning these regulations. My experience with FAA inspectors is they are really trying to make compliance as easy as possible and are not trying to make your life miserable.

Tom

That definition of minor change leaves very wide latitude for minor changes.. Also great latitude for judgement about what is considered a minor change..