"T o d d P a t t i s t" wrote in message
...
[...]
Oddly enough, in reviewing the certification requirements, I found two
paragraphs that my own airplane doesn't appear to meet.

Very interesting.

Well, I had a chance to ask my mechanic about this today. Unfortunately, he
wasn't completely certain about the answer either. However, it *appears*
that it's related to the original type certificate being issued under CAR 3,
rather than FAR 23.

The thing that he couldn't figure out (nor could I) is that on the TC Data
Sheet says (for my airplane type) "Certification Basis: 1. 14 CFR Part 23,
18 December 1964, Amendments 23-1 to and including 23-23, Subparts A, B, D,
E, F, and G." It goes on to also say "2. CAR 3...", but I don't understand
why they would list all the bits of FAR 23 if the type doesn't actually have
to meet the requirements of that Part.

However, it is true that my airplane shares the exact same TCDS number as
the original CAR 3 airplane from which it was derived (in spite of being
about as similar to it as a Cessna 206 is to a Cessna 150). So maybe that's
the answer, regardless of the mention of Part 23 in the TCDS. I have to
admit, it's a bit entertaining reading through the TCDS, seeing the
evolution of the type. Each new version is described as "exactly like the
previous, except...". Some of the exceptions are pretty broad.

It does appear that generally the requirements in question (manual override,
pilot indication) are met by other aircraft with automatic alternate air
induction sources, or at least two of them. The guys at the shop all agreed
that the Piper Navajo and Seneca both have those features to go along with
their automatic alternate air (I don't know firsthand myself...I'm just
taking their word for it).

If there's anyone out there who actually knows something about how aircraft
type certificates are granted who wants to take a look, here's the TCDS:
http://www.airweb.faa.gov/Regulatory_and_Guidance_Library/rgMakeModel.nsf/0/e906cc8a49ec031586256f7e0064e791/$FILE/1a13.pdf

The URL looks suspiciously to me as though it may contain a session ID, and
so it may not be valid by the time anyone else reads this post. But you can
navigate to the sheet by going he
http://www.airweb.faa.gov/Regulatory...e?OpenFrameSet
and then looking up the TCDS direction (it's 1A13, just like the name of the
PDF file in the previous link).

Anyway, fun with type certificates...

Pete