24 MO transponder check req?

[bret]

Going through the Dynon manual I came across this, so do I still need this check for the AW inspection?


In most transponder systems, a calibration is normally carried out every 24 months, as part of the altimeter checks on the aircraft. The maximum allowed difference between the primary altimeter and the altitude encoder is 125 feet in ETSO C88a and TSO C88b. The primary altimeter in SkyView and the altitude encoder are the same device (SV-ADAHRS-200/201). It is therefore impossible for the encoder and the primary altimeter to exceed 125 feet of altitude difference. They will always be exactly the same as each other, thereby meeting the TSO requirements. Therefore, no altitude encoder calibration is possible or necessary.

[BobTurner]

Yes it needs to be done. Other things (transmits correct squawk code, transmitter power output, ...) are also checked.

[sf3543]

Technically, a txp check is not required for the aircraft to be considered airworthy. It is required; however, if you plan to fly in controlled airspace that requires a txp, such as the thirty mile veil around the DFW class b space, etc.

[rv7charlie]

Not to split too fine a hair, but isn't it true that while you can operate the a/c (in permitted airspace) without the xp check, you can't legally operate the transponder itself?

[Infidel]

Originally Posted by rv7charlie

Not to split too fine a hair, but isn't it true that while you can operate the a/c (in permitted airspace) without the xp check, you can't legally operate the transponder itself?

Yes, that's my understanding.

[PCHunt]

IMHO, somewhere in the FAR's it is stated that if you have a transponder installed, you are required to use it. Even if you are in airspace that doesn't require a transponder.

[jcaplins]

Originally Posted by PCHunt

IMHO, somewhere in the FAR's it is stated that if you have a transponder installed, you are required to use it. Even if you are in airspace that doesn't require a transponder.

Yes. But you can placard the transponder as inop, and fly without it turned on.

[BobTurner]

Originally Posted by PCHunt

IMHO, somewhere in the FAR's it is stated that if you have a transponder installed, you are required to use it. Even if you are in airspace that doesn't require a transponder.

The FAR you're thinking of says you must use it if it is installed and inspected biennially. If not inspected within the past 24 months, it must be placarded "inoperable", and not used. Then the rules for no transponder aircraft apply.

[rv7charlie]

If it's not been signed off, or the 24 months has run, it's 'inop', therefore not legally installed. Sort of.

Seriously, that specific scenario was discussed during a FAAST briefing, and the FAA safety guy said that as long as you observe the airspace limits, it's legal to fly the plane.

Charlie

[BobTurner]

Originally Posted by jcaplins

Yes. But you can placard the transponder as inop, and fly without it turned on.

Careful - the FARs require you to operate any operable transponder which has been inspected in the past 24 months. There is no provision to put an inop sticker on it just because you don't want to use it. It really has to be broken or out of compliance with the 24 month inspection.

A few years ago instrument applicants were showing up for instrument flight practical tests with an ADF placarded "inop", as students apparently didn't like NDB approaches. The FAA told examiners to demand proof, like aircraft logbooks signed by an A&P stating the ADF was really not working, and that they had 'disabled' the radio in question.