"Thomas Borchert" wrote in message
...

Hmm. I remember differently.


So what do you remember?



How do you explain GPS IFR enroute
certification, which is available for some panel-mounts?


I assume you're referring to TSO C-129a. It exists, but it's mere existence
does not prohibit the use of equipment that hasn't been demonstrated to meet
the standard.

TSOs are not regulations, they are Technical Standard Orders. TSOs are not
binding unless there is an FAR that requires the TSO to be complied with, so
says FAR 21.601. There are TSOs in existence that cover the "approval" of a
great many things, but you don't have to use "approved" equipment in any
operation unless required to do so by the FARs. What FAR requires
compliance with TSO-C129a?


PART 21--CERTIFICATION PROCEDURES FOR PRODUCTS AND PARTS


Subpart O--Technical Standard Order Authorizations


Sec. 21.601 Applicability.


[snip]


(b) For the purpose of this subpart--


[snip]


(4) An article manufactured under a TSO authorization, an FAA letter of
acceptance as described in §21.603(b), or an appliance manufactured under a
letter of TSO design approval described in §21.617 is an approved article or
appliance for the purpose of meeting the regulations of this chapter that
require the article to be approved.