Is there a difference in a VFR and IFR transponder check?

I am trying to get my 24 month transponder check completed. The local avionics guy is telling me his transponder check will be a VFR transponder check. Is there a different 24 month transponder check required if I wanted to fly IFR?

I am not talking about the pitot static check. I realize that too is required for IFR flight. I'm just trying to understand if there are 2 different transponder checks done depending on ifr or vfr.

Does the avionics guy have the ability to give me a VFR only transponder check??

unless something has changed, 91.413 is your transponder check that must be done every 24 months regardless of vfr/ifr. 91.411 must be done for altimeter accuracy and static system check for ifr. they are usually done at the same time when IFR equipped.

Jay

We at SteinAir are an FAR Part 145 Repair Station for transponder and pitot/static testing. The transponder and encoder testing for VFR and IFR are the same. For VFR, only the transponder and encoder is tested, at field elevation. Correlation is also tested to the onboard altimeter(s). This test is required by FAR 91.413, and shows the equipment performance complies with FAR part 43, Appendix F, for VFR flight only.
The IFR test is required by FAR 91.411, and involves testing the pitot/static and altimeter system for compliance with FAR Part 43, Appendix E. This would be in addition to the VFR testing. An aircraft flown under IFR must show compliance with Appendix E and Appendix F of Part 43.
Some avionics shops will tell you they can't do VFR testing but we specifically cleared this with our FSDO when we set up the repair station, so it is their choice if they won't do them.
Even if it is only to be flown VFR, I would do the IFR testing on a newly built aircraft to establish the integrity of the pitot/static system. After that, a leak check after breaking into the system should be sufficient.

Quicky version

In short.... the VFR one is done at field elevation, where the IFR one involves a machine that puts "suck" into the static system.

The involvement of this machine usually adds $100+ to the test.

If you want to make things easier for future IFR testing, add an accessible T fitting to the static line for the machine to hook up to. This way the static ports can simply be taped over for the test. After the test, you can perform a leak test to ensure the static system wasn't compromised by the T fitting.

If you have a Dynon system, make sure the tester knows how to put it into test mode.

That's what I thought. A transponder check is a transponder check is a transponder check. If the transponder/encoder passes the test, It's good for ifr and vfr transponder compliance.

I do realize one would also need a pitot static check to be ifr legal, and I realize the static system ties into the encoder.

From the FAQ page of my site:

What inspections are required for VFR operations?
The aircraft transponder must be certified every 24 months in accordance with the requirements of CFR. 91.413. Transponder testing is accomplished in accordance with Part 43 Appendix F.

Note: For new certifications or if the encoder or altimeter has been replaced, a Data Correspondence Check must be accomplished to ensure the altitude data transmitted to ATC corresponds to within 125 feet of the altimeter normally used to maintain flight altitude per CFR 91.217.

(no difference between VFR and IFR for the transponder itself)

For IFR:
In addition to the 24 month transponder check, if you fly your aircraft IFR, you must comply with the pitot/static test requirements called out in 14 CFR 91.411. As with transponders, this regulation applies to all aircraft, regardless of certification category. These tests include certifying the altimeter and altitude encoder and checking the static system for leaks.

Note: on an unpressurized aircraft there is no legal requirement to do a "Pitot" leak check.

Thanks for you input Walt. I was hoping your would post. I actually went to your website and saw your FAQ section after posting my question here.

What the FARs say -

To be specific and to reference the regulations, here they are -

For IFR flight -

https://www.law.cornell.edu/cfr/text/14/91.411

This calls out two subsections (E and F) of Part 43

This Appendix E calls out the altimeter/altitude reporting testing and accuracy -

https://www.law.cornell.edu/cfr/text/14/appendix-E_to_part_43

Appendix F calls out testing of the transponder itself, with an additional section for Mode S transponders -

https://www.law.cornell.edu/cfr/text/14/appendix-F_to_part_43

BUT if you are VFR only, then this paragraph of Part 91 applies -

https://www.law.cornell.edu/cfr/text/14/91.413

And it only calls out Appendix F above.

So the cost difference is in testing for Appendix F only vs. testing for both Appendix E and F.

That looks like it supports the fact that a transponder check is a transponder check. None of the info listed in 14 CFR Appendix F, nor the 14 CFR 91.413 make any statement about IFR or VFR.

91.413 says the transponder has to be checked every 24 months and in Appendix F is a list of things that your transponder has to be able to perform in order to pass the inspection.

I can see how one could argue both sides on this issue, since in order to be IFR legal, as described in Appendix E, your transponder is tested again during the pitot static check.

Only one side -

blueflyer said:

That looks like it supports the fact that a transponder check is a transponder check. None of the info listed in 14 CFR Appendix F, nor the 14 CFR 91.413 make any statement about IFR or VFR.

91.413 says the transponder has to be checked every 24 months and in Appendix F is a list of things that your transponder has to be able to perform in order to pass the inspection.

I can see how one could argue both sides on this issue, since in order to be IFR legal, as described in Appendix E, your transponder is tested again during the pitot static check.

Click to expand...

Nah... the Appendix sections are only a "how to". There are not two sides if you read carefully.

The Part 91 paragraphs are the actual regulations and they are quite specific for the IFR case.

The first sentence of Appendix F states very clearly that it is a "how to" rather than a regulation -

The ATC transponder tests required by § 91.413 of this chapter may be conducted using a bench check or portable test equipment and must meet the requirements prescribed in paragraphs (a) through (j) of this appendix.

Same with Appendix E -

Each person performing the altimeter system tests and inspections required by § 91.411 shall comply with the following:



The "IFR legal" you mention is not based on Appendix E as you state, but is based on 91.411 (a) (1) which calls out both Appendix E and Appendix F.