installing a transponder in a vintage aircraft
I have a 1942 Taylorcraft L2 that has no electrical system. I would like to install a transponder so that I can keep it at a class C airport. Having a panel or permanently mounted radio would also be nice.
The type certificate specifies three specific batteries, none of which seem to be made today. A wind generator is also specified in the type certificate. I have that model of wind generator but not the mounting equipment for it.
Before I contact the FSDO I thought that I would ask these questions here:
1. Can I install a battery other than the one specified in the type certificate? (I am thinking of an Odessy PC 680 or similar) If so, do I file a 337?
2. Assuming that the transponder will be TSO'd can I install it with a 337? I will probably go with a microair or similar small transponder with a low current draw.
Is there anything else that I should know? I want to identify all the "gotcha's" before I start this project.
10 years ago I did the same thing. I put a Garmin SL60 COM/GPS/ICS, Garmin GTX327 and Basic Aircraft Products wind generator in a J-3 Cub. The inspector required that I have provisions to monitor the battery health, so I put in an Electronics International Volt/Amp meter. I also installed a solar recharge system to keep the battery topped off.
You will need to make a ground plane for the XPDR antenna. I used a circular piece of aluminum the radius of which was equal to the height of the XPDR antenna. It was pollytacked in place and I used ground strap to the airframe.
I use a 12V 12A Sealed Lead Acid Battery. It is not aviation certified. I asked my FSDO before hand and they said "43.13" - On my 337 I referenced it for the installation and they did not question my choice of battery. 2 years later I did a similar installation with a friend and he used a 12 V/7 A Sealed Lead Acid battery and they did not question that battery either.
The inspector had 2 comments on the installation: I needed to put the standard "GPS IS NOT APPROVED FOR IFR" placard in view of the pilot and he recommended that I drill a hole in the side of the wind alternator to install a hard mounted fuse, rather than the inline fuse I used. He was right on both counts. I can send you a complete package on my installation with copies of the 337's
Cub electrical panel 1.jpg
Last edited by firstname.lastname@example.org; 09-22-2011 at 09:53 PM.
Pete, thanks for your response. If you have the paperwork you filed in electronic form it would be great if you could email it to me. I am sending you and email.
Transponder installation in vintage aircraft.
I installed a Terra Transponder (TRT-250) in my 1941 Interstate S-1A Cadet which has no electrical system. The Terra installation Manual said that any power supply from 4 to 24 volts was useable, so my power supply is a 12 volt battery. I am an A&P and I.A. and did it on a 337 Form and received a Field Approval from my local FSDO.
I accomplished this installation in the early 1990's. I could send a copy of my 337 if you want.
ok - send me your address and I will mail it - the drawings are on 11x17 paper.
Could you please send me a copy of your drawings for the instalation of a radio and transponder in a Taylorcraft D-12
9390 Tulane Rd.
Vintage A/C Transponder installs
Originally Posted by N12tj
I am trying to get together a design very similar to what you have described except that I plan on going with the Odyssey SJ16 battery which is a near ident equal to the PC680 but has an FAA granted PMA for its usage in aircraft. Mine is to be for an Aeronca Chief but I am going to go around the wind turbine in the belief that for the very small current draw of the new minaturized transponders, the dry mat batteries will provide sufficient power for much longer than the nominal flight durations of this kind of aircraft (IMHO) This approach has been utilized in high performance gliders successfully. It is my understanding that you(we) will require the assistance of an IA to qualify the installation. This is a maybe. I intend to use one anyway. There will be a requirement for a 337. Check out FAA Advisory Circular 43.9-1F which essentially walks you through the necessary steps to prepare the 337. It is available online. This approach means, of course, that I will have to recharge the dry mat batt at some interval. I hope to be able to do this with a trickle charger such as I currently use on my garden tractors and ATV, all of which are 12V systems. Please let me know if you make any significant discoveries as you go along particularly in the areas of acceptable SOC systems and recharge of dry mats. You may do so by posting here or, if you wish, make direct contact with me at email@example.com. Good Luck with your project.
Thanks for sending that information. My current plan is to use some of the most recent technology, to include a low drain transponder, perhaps the Trig model which also supports ADSB squiter out, and a small low drain radio. Trig is developing one that is supposed to be out on Jan 13 and available through aircraft spruce as well as other outlets. Mr. Weiskoph was kind enough to send me a copy of his 337 for a similar installation that is pictured in a post above. I plan to use his basic plan.
I have put off this project for some time but plan on working on this issue withing the next few months. I would be interested in what you learn on your project as well.
My former PMI from the Renton, WA FSDO, has told me that an only an A&P with an Inspection Authorization (or other FAA Designees DAR, DER, etc) may sign block 7 Approval for Return to Service of a Form 337, so if I am right, the comments above suggesting use of an IA for a 337 is optional, are incorrect.
-Joel Marketello, A&P, IA
To All reading this thread. DO NOT READ MY 11/29/2012 AS IMPLYING A 337 COULD BE SIGNED OFF BY ANYONE OTHER THAN A PERSON ACCEPTABLE TO THE FAA ! I only meant to say that some portion of the work necessary to complete the installation could be performed under the guidance of a certified A&P or IA with his blessing. There is no question that the equipment and installation must fully comply with the applicable regulations of the FAR. I apologize for any misunderstanding my phrasing may have caused. N12tj, I will be happy to share with you any further information I become aware of in this regard.