ADS-B - Encoder not working

[ateamer]

I have a mixed panel - older Dynon D6 and the rest is round instruments, with a GTX335 sending ADS-B Out. Lately the Dynon has been not coming on, or intermittently working. It wasn’t a concern because I only fly day VFR and there is a backup airspeed and altimeter.

And then I noticed the message on the transponder that pressure altitude is missing. Turns out that the encoder is in the Dynon. It appears that the problem is the wire bundle connector on the back of the instrument and I have an appointment with an avionics shop.

But until they can get me in, the plane is grounded and it’s frustrating. Reading 91.225(f), ADS-B has to be on at all times no matter where. 91.227(d)(3) requires pressure altitude to be broadcast. Am I getting that right? Can’t fly outside rule airspace with ADS-B not sending pressure altitude, and can’t just turn it off.

 

[unsafervguy]

I have a mixed panel - older Dynon D6 and the rest is round instruments, with a GTX335 sending ADS-B Out. Lately the Dynon has been not coming on, or intermittently working. It wasn’t a concern because I only fly day VFR and there is a backup airspeed and altimeter.

And then I noticed the message on the transponder that pressure altitude is missing. Turns out that the encoder is in the Dynon. It appears that the problem is the wire bundle connector on the back of the instrument and I have an appointment with an avionics shop.

But until they can get me in, the plane is grounded and it’s frustrating. Reading 91.225(f), ADS-B has to be on at all times no matter where. 91.227(d)(3) requires pressure altitude to be broadcast. Am I getting that right? Can’t fly outside rule airspace with ADS-B not sending pressure altitude, and can’t just turn it off.

you are correct. adsb, if installed must be on and operable at all times. it cannot just be labeled inop and logged and away you go. the only legal way is to remove the system, complete all paperwork for the removal, including 337's to document the removal of equipment that was installed with a 337 and then a return to service and stay out of rules airspace.

 

[FORANE]

Pull the D6 install manual and look at the pinout for the harness. Locate the 2 arinc wires that supply altitude encoder data to your transponder. I would do the same for arinc in on the transponder harness. You will likely find a bad crimp on one of the pins. Pulling the harness will be the most difficult part of the job. That's why some experimental guys are going to fully removable panels.

 

[ateamer]

Pull the D6 install manual and look at the pinout for the harness. Locate the 2 arinc wires that supply altitude encoder data to your transponder. I would do the same for arinc in on the transponder harness. You will likely find a bad crimp on one of the pins. Pulling the harness will be the most difficult part of the job. That's why some experimental guys are going to fully removable panels.

I didn’t go into more detail in the OP, but it’s most likely the power pin (top left). The plane goes in this week for them to fix it. I don’t have the skill or tools to fix it myself. Hmm, maybe I should buy some parts and tools and learn.

It is a bit of a pain getting to the plug. I have an RV-8A. Access is through a panel in the forward baggage compartment. If I ever put in a new panel, it’s going to be hinged across the bottom with big enough service loops in the wiring to just unscrew the the top and fold the whole thing down.

 

[WDD]

Some day - wouldn't it be nice - if all the components just plugged into each other with a UCB C connection. Never going to happen......

 

[asicer]

Some day - wouldn't it be nice - if all the components just plugged into each other with a UCB C connection. Never going to happen......

I wouldn't doubt that it will happen... Right before USB-D is released.

 

[John Collins]

you are correct. adsb, if installed must be on and operable at all times. it cannot just be labeled inop and logged and away you go. the only legal way is to remove the system, complete all paperwork for the removal, including 337's to document the removal of equipment that was installed with a 337 and then a return to service and stay out of rules airspace.

The regulation says you have to operate it at all times, it does not say you have to remove it. Operating an ADS-B Out system without an input will still broadcast the information it does have, just that in this case the altitude will be missing or noted as unavailable.

 

[unsafervguy]

The regulation says you have to operate it at all times, it does not say you have to remove it. Operating an ADS-B Out system without an input will still broadcast the information it does have, just that in this case the altitude will be missing or noted as unavailable.

no. from 91.225:
§ 91.225 Automatic Dependent Surveillance-Broadcast (ADS-B) Out equipment and use.
(a) After January 1, 2020, unless otherwise authorized by ATC, no person may operate an aircraft in Class A airspace unless the aircraft has equipment installed that -

(1) Meets the performance requirements in TSO-C166b, Extended Squitter Automatic Dependent Surveillance-Broadcast (ADS-B) and Traffic Information Service-Broadcast (TIS-B) Equipment Operating on the Radio Frequency of 1090 Megahertz (MHz); and

(2) Meets the requirements of § 91.227.

(b) After January 1, 2020, except as prohibited in paragraph (i)(2) of this section or unless otherwise authorized by ATC, no person may operate an aircraft below 18,000 feet MSL and in airspace described in paragraph (d) of this section unless the aircraft has equipment installed that -

(1) Meets the performance requirements in -


(i) TSO-C166b; or


(ii) TSO-C154c, Universal Access Transceiver (UAT) Automatic Dependent Surveillance-Broadcast (ADS-B) Equipment Operating on the Frequency of 978 MHz;


(2) Meets the requirements of § 91.227.

91.227 calls out the standards it must meet.
if it does not meet 91.227 then it is inoperative. also from 91.225:
(f) Except as prohibited in paragraph (i)(2) of this section, each person operating an aircraft equipped with ADS-B Out must operate this equipment in the transmit mode at all times unless -
(g) Requests for ATC authorized deviations from the requirements of this section must be made to the ATC facility having jurisdiction over the concerned airspace within the time periods specified as follows:

(1) For operation of an aircraft with an inoperative ADS-B Out, to the airport of ultimate destination, including any intermediate stops, or to proceed to a place where suitable repairs can be made or both, the request may be made at any time.

(2) For operation of an aircraft that is not equipped with ADS-B Out, the request must be made at least 1 hour before the proposed operation.

so, if it is installed it must work, meeting all of the requirements of the tso and all parameters. if it is not working you can request a exemption from atc to get it to a place to fix it or your final destination. thats the way the fars are written.
if any part of the system does not meet tso, then you can get a exemption to fly it to your destination, or to a place to get it fixed. otherwise, you must remove it and do the paperwork. there is no "inoping" it and flying around.

i would suggest you read this: https://sapt.faa.gov/faq.php#do_need_adapt
especially questions 3,4, 11

 

[GeorgeC]

I wish I'd known all that when I had to get my 335's antenna replaced, I just called ATC and worked it out with them and flew to the shop and got it fixed