Bi-annual transponder check

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Gone Flyin

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Gone Flyin
What is the bi-annual mode c transponder check supposed to include?

That is, what is the technician testing for when he hooks up his box to your plane and what must be the result for each test (parameter wise) to give you a re-certification for another two years?

Thanks
 
I don't know the parameters. They need to verify the power output, I think, and that all of the modes and buttons work. It needs to output the altitude as well. That is a VFR Cert. For an IFR Cert, they need to verify that your altimeters are correct up to a high altitude (20,000' usually) with a certain amount of allowed error. Then they make sure there are no significant leaks in your static system.
 
I think that's what bi-annual means. Twice a year would be semi-annual, wouldn't it?

...Edit - According to the dictionary it should be biennial for every other year. It also says that semiannual would mean every 6 months normally, but biannual means every 6 months according to the Google dictionary.
 
Jesse Saint said:
I don't know the parameters. They need to verify the power output, I think, and that all of the modes and buttons work. It needs to output the altitude as well. That is a VFR Cert. For an IFR Cert, they need to verify that your altimeters are correct up to a high altitude (20,000' usually) with a certain amount of allowed error. Then they make sure there are no significant leaks in your static system.
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When mine was done for VFR they verified the altimeter, tested for leaks, transponder power output, and that the transmitted frequencies were correct. They did a great job.
 
Gone Flyin said:
What is the bi-annual mode c transponder check supposed to include?

That is, what is the technician testing for when he hooks up his box to your plane and what must be the result for each test (parameter wise) to give you a re-certification for another two years?
Click to expand...
Here is an overview of the whole process:

 
It also depends on which sort of transponder you have. If you've got a mode S, it's more involved.

In addition to the transponder itself, your encoder has its own tests. If you're going to fly IFR, then you also have to have the altimeter checked.

The latter is the most time consuming as it involves bringing the altimeter up and down through its range testing both accuracy and response as you go.
 
I'm due for my 24 month transponder check. Should I be able to remove my transponder and take it to an avionics repair station for the test?
I'm reading FAR Part 43 Appendix F, and it says that the requires tests "may be conducted using a bench check". I've contacted a couple of avionics shops in my area, and they are telling me that I would need to bring them the plane. I'm just curious if anyone has been able to just take their transponder in for the tests.
 
Tom Braeunig said:
I'm due for my 24 month transponder check. Should I be able to remove my transponder and take it to an avionics repair station for the test?
I'm reading FAR Part 43 Appendix F, and it says that the requires tests "may be conducted using a bench check". I've contacted a couple of avionics shops in my area, and they are telling me that I would need to bring them the plane. I'm just curious if anyone has been able to just take their transponder in for the tests.
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If you have mode C or Mode S (ie an altitude encoder) they need that also, and since they have to test via the pitot/static system you can't simply mail it in.. they have to test the entire system.

For a non-encoding xpndr, they can bench test it as there are no external devices to test... Just check the power, freq and data stream.
 
Tom Braeunig said:
I'm due for my 24 month transponder check. Should I be able to remove my transponder and take it to an avionics repair station for the test?
I'm reading FAR Part 43 Appendix F, and it says that the requires tests "may be conducted using a bench check". I've contacted a couple of avionics shops in my area, and they are telling me that I would need to bring them the plane. I'm just curious if anyone has been able to just take their transponder in for the tests.
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Who is going to re-install the transponder?

Part 43, appendix A, C preventive maintenance 31 "excluding automatic flight control systems, transponders"
 
You can't do all the required tests on a mode S transponder on the bench. The test procedure spelled out in the regs specifically requires you to have it connected to the aircraft antenna.
 
Agree with previous posts. A transponder check done properly also verifies the antenna is connected properly. The only time I had a transponder test done on the bench was after purchasing a used transponder before installing it in the aircraft.
 
Tom Braeunig said:
I'm due for my 24 month transponder check. Should I be able to remove my transponder and take it to an avionics repair station for the test?
Click to expand...
Tom Braeunig said:
they are telling me that I would need to bring them the plane.
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No. While you can have part of the 24mo test complied with by sending your xspndr to a shop you still need the aircraft for the complete test and signature. Part 91.413(b) is where that comes in. Technically any xspndr removed/installed requires a minimum of one data point/altitude verified via a correspondence check after installation or mx regardless of type. Plus, you'll need a CRS to perform said correspondence test unless you're a 135/121 ops or an OEM.
 
Bell206 said:
No. While you can have part of the 24mo test complied with by sending your xspndr to a shop you still need the aircraft for the complete test and signature. Part 91.413(b) is where that comes in. Technically any xspndr removed/installed requires a minimum of one data point/altitude verified via a correspondence check after installation or mx regardless of type. Plus, you'll need a CRS to perform said correspondence test unless you're a 135/121 ops or an OEM.
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Further the Appendix F places more requirements and as CapnGeoff points out, playing with transponders is NOT an owner maintenance item anyhow.
 
Daleandee said:
When mine was done for VFR they verified the altimeter, tested for leaks, transponder power output, and that the transmitted frequencies were correct. They did a great job.
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As I recall on my VFR transponder check. They walked by the hanger with a box, set it next to the glider had me power up the transponder. I don't recall what settings they had me select but it was not very much. Got a photo of the dataplate on the the transponder. Closed picked up the box and kept walking. They were done in probably under 5 minutes. I picked up a signed sticker at the office (after giving them $100 IIRC) about an hour later.

Brian
 
The mode S check isn't much more than that. The test unit simulates the interrogations and evaluates the responses. If you have an encoder however, there should have been more to it than that.
 
brcase said:
As I recall on my VFR transponder check. They walked by the hanger with a box, set it next to the glider had me power up the transponder. I don't recall what settings they had me select but it was not very much. Got a photo of the dataplate on the the transponder. Closed picked up the box and kept walking. They were done in probably under 5 minutes. I picked up a signed sticker at the office (after giving them $100 IIRC) about an hour later.

Brian
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Seems strange to say but I've had a transponder check for VFR much like what you have described. But the last one, done at the same facility, involved them removing the pitot and connecting to my pitot and static lines to check the system. They had someone else in the plane operating the transponder and reading the altimeter. It passed with flying colors.

I wondered why they did it differently than before but there were a few of what appeared to be newbies working with the guy doing the check so maybe it was for them to learn something. Costs was the same so I wasn't going to complain about them giving it the once over at the same cost.
 
flyingron said:
Further the Appendix F places more requirements
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Of course, but the point I was making was even outside of a 413 check a function check is still technically required when a transponder is slide out of the rack and reinstalled to include by an AP. T
flyingron said:
If you have an encoder
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FYI: the encoder tests are actually under 411 and Appx E and not 413 which is just checking the radio side. 91.217 deals with encoders but has no time limit. So long as the installed encoder is not replaced or a new encoder is not installed, a VFR 413 transponder check does not require pumping up the encoder.
 
Daleandee said:
Seems strange to say but I've had a transponder check for VFR much like what you have described. But the last one, done at the same facility, involved them removing the pitot and connecting to my pitot and static lines to check the system. They had someone else in the plane operating the transponder and reading the altimeter. It passed with flying colors.

I wondered why they did it differently than before but there were a few of what appeared to be newbies working with the guy doing the check so maybe it was for them to learn something. Costs was the same so I wasn't going to complain about them giving it the once over at the same cost.
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How much was it?
 
mandm said:
How much was it?
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It was done 11/20 and IIRC it was $125.00. Due again later this year and I hope to use the same shop so we'll see how it's done this time.
 
Daleandee said:
Seems strange to say but I've had a transponder check for VFR much like what you have described. But the last one, done at the same facility, involved them removing the pitot and connecting to my pitot and static lines to check the system. They had someone else in the plane operating the transponder and reading the altimeter. It passed with flying colors.

I wondered why they did it differently than before but there were a few of what appeared to be newbies working with the guy doing the check so maybe it was for them to learn something. Costs was the same so I wasn't going to complain about them giving it the once over at the same cost.
Click to expand...

If they messed with the Pitot or static it sounds to me like they were performing at least part of an IFR check. Like you said, it might have been for training. so you may have got a free pitot static check even if it wasn't legally logged that way.
Brian
 
Daleandee said:
It was done 11/20 and IIRC it was $125.00. Due again later this year and I hope to use the same shop so we'll see how it's done this time.
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Yeah I was told a pitot static check runs $600 plus any issues identified (fixing a static leak, new transponder, etc)
 
brcase said:
If they messed with the Pitot or static it sounds to me like they were performing at least part of an IFR check. Like you said, it might have been for training. so you may have got a free pitot static check even if it wasn't legally logged that way.
Brian
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Again, there's nothing on the pitot system that needs looking at IFR or VFR. The checks are purely on the static side (altimeter, encoder, and their connection to the ambient air).
 
mandm said:
Yeah I was told a pitot static check runs $600 plus any issues identified (fixing a static leak, new transponder, etc)
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Our last one on the C340 with dual pitot static systems, altimeters, encoders and transponders was $775. February of 2021, done in our hangar, DFW area. No repairs needed. The guy had everything he needed including a small GPU.
 
They do IFR pitot static, transponder checks here for $300...at your hangar.
 
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