jcarlyle wrote:
Eric, with respect Chip is correct. I found the FARs to be very
confusing on this subject. After some research, though, I'm pretty
sure that the following interpretation is correct:
For VFR operations the applicable paragraphs are 91.413, and Part 43
Appendices E and F. You start with 91.413(a). This requires that every
two years you must have transponder electrical checks done in
accordance with 43 Appendix F. As you'll see, if you have a Mode S
transponder there are a lot more checks, so it is more expensive.
This part I've always accepted.
Again for VFR, if you've just installed (or done some maintenance) on
a transponder that will be used in VFR operations, you then must
follow 91.413(b). This leads you to 43 Appendix E paragraphs (c) and
(a), which together require the static system to be leak tested,
followed by doing an altitude correspondance test between the
altimeter and the transponder in which they must agree to within 125
feet. Notice this gets you out of paragraphs (b) and (d), which are
rigorous altimeter checks and record keeping, which makes the testing
cheaper for VFR.
This was the confusing one, but after going around in circles in the
CFRs for at least 30 minutes, I have to agree with you. It's confusing
because 43 Appendix E references 91.411, which is clearly IFR only. It
took a while to realize 91.413(b) points just to 43 Appendix E (c), not
to the entire 43 Appendix E. And, then (c) points back to (a)! Cheez, it
takes a flow chart to keep things straight.
It would be clear if they copied 43 E (a) and 43 E (c) and made those
paragraphs part of 91.413(b), instead of forcing you to go from section
to section, but they don't do that.
Now I'm puzzled that the regs insist on IFR quality data correspondence
for the initial installation, but with no checks after that as long as
you don't change anything.
--
Eric Greenwell - Washington State, USA
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* "A Guide to Self-launching Sailplane Operation" at
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