What’s the deal with these transponder/altimeter certifications?
Do I need them?
How often are they required?
What happens if my aircraft won’t pass?

I get asked these questions on an almost daily basis so here are the answers:

Per FAR 91.411,

(a) No person may operate an airplane, or helicopter, in controlled airspace under IFR unless —

1. Within the preceding 24 calendar months, each static pressure system, each altimeter instrument, and each automatic pressure altitude reporting system has been tested and inspected and found to comply with appendix E of part 43 of this chapter;
2. Except for the use of system drain and alternate static pressure valves, following any opening and closing of the static pressure system, that system has been tested and inspected and found to comply with paragraph (a), appendices E and F, of part 43 of this chapter; and
3. Following installation or maintenance on the automatic pressure altitude reporting system of the ATC transponder where data correspondence error could be introduced, the integrated system has been tested, inspected, and found to comply with paragraph (c), appendix E, of part 43 of this chapter.
   

And Per FAR 91.413,

1. No persons may use an ATC transponder that is specified in 91.215(a), 121.345(c), or §135.143(c) of this chapter unless, within the preceding 24 calendar months, the ATC transponder has been tested and inspected and found to comply with appendix F of part 43 of this chapter; and
2. Following any installation or maintenance on an ATC transponder where data correspondence error could be introduced, the integrated system has been tested, inspected, and found to comply with paragraph (c), appendix E, of part 43 of this chapter.

So what does this mean? You cannot fly IFR unless your altimeters, encoders and static systems have been tested within the past 24 months and you must have your transponder checked every 24 months or following any type of maintenance that would affect the accuracy of your altimeter or transponder.

I’ve heard some IA’s who think the annual is not complete until either of these tests have been done or the aircraft is not airworthy unless they are done, well it’s not so. You just can’t fly IFR or turn on your transponder! If your aircraft won’t pass either certification, Direct Avionics can handle the repairs needed to get your aircraft certified.