Transponder in No Electrical System T-Craft

[Forrest Barber]

Re: Transponder in No Electrical System T-Craft

The standard ELT "tray" fits quite well. I would watch putting it into a "glove" box. No ventilation, they are very easy to overheat. Radio too, check for cooling air around most radio stacks. Sorry i ahve been off for 5 days. Got booted off my own web site. Had to get a new password, no I did not "log out " either. It was a learning experience.

[DanBrown]

Re: Transponder in No Electrical System T-Craft

After some months of frustration, I flew to Lancaster, PA (LNS) yesterday where the helpful folks at Lancaster Avionics got an OK from the Harrisburg FSDO to test my portable box for a bi-annual transponder check and enter it in my log. Simple and quick. A photo of the box is attached. It straps in front of the seat, and runs the transponder and encoder for 7 hours on a 5 amp-hour radio shack sealed gel cell battery. Charging is through the cigeratte lighter socket on the side. The antenna is mounted under the fusalage and easily plugs in to the transponder. The whole unit weighs about 7 pounds.

Neither the Baltimore or Dulles FSDO would let a shop do the test without a field approval (which they wouldn't consider granting). At least one FAA office considers the safety value of an airplane with a working transponder flying in a high density traffic area outweighs the strict following of someones guidelines.

Many thanks for all the suggestions from the tribe.

[d.grimm]

Re: Transponder in No Electrical System T-Craft

Dan,
This is really neat. Let me get this straight. The transponder/encoder is all in this box and the FAA signed off on it. Do you have some more info like, prices,
contact names, type of equipment, how long the transponder works on a single charge.
Dave

[DanBrown]

Re: Transponder in No Electrical System T-Craft

I put the box together using an Aluminum chassis from www.newark.com, standard analog volt and ammeters, switches, fuse holders and closed gel cell battery from Radio Shack, a Microair transponder and Trans-Cal encoder from Aircraft Spruce.
The combination draws about .4 amps, which runs 7 hours on a charge -- the encoder stops working when the battery voltage drops to 10.5.
There was no field approval needed -- just a logbook entry that the transponder installed meets the requiements of FAR-91-413 and FAR 43 Appendix F.

[Forrest Barber]

Re: Transponder in No Electrical System T-Craft

PLEASE send all this information direct to me at the Foundation, we have done this before, BUT other FSDO's would not accept.
Lets see copies of log entries and box and parts , etc.... thank you Forrest I have copied this thread to a file too! [email protected]
atta boy

[DanBrown]

Re: Transponder in No Electrical System T-Craft

Forrest,

Thanks for the comments.

I'll put together more information in the next couple of weeks and post it on the forum. The key is finding a electronics shop that has done similar installations in the past on gliders or baloons, and who has good relations with their FSDO, and then going there for the checkout.

[Forrest Barber]

Re: Transponder in No Electrical System T-Craft

That is how it is done, have enough acceptable data to present to the FSDO PMI and get approval before doing it!! thank u for the effort, this is needed.

[Hank Jarrett]

Re: Transponder in No Electrical System T-Craft

Years ago I sent a letter to Jim Weir asking about doing a set of plans to make a portable Transponder and his response was something like most guy out there aren't smart enough or skilled enough to build one. At the time, this rocket scientist was a little insulted by that, but since I had PLENTY of other projects around I never pushed it (doesn't hurt that I'm NO electronics guy and know I COULDN'T do it alone).
What is the interest level out there in bulk buying the parts and passing out kits for these little beauties. I KNOW I could put one together and probably so could the rest of us (maybe people who fly Taylorcrafts are just smarter than Jim's average reader). Any idea what your total parts investment was? If we commit to that much and can get a break on the prices of parts by buying in bulk we might end up with a really good deal on 15 or 20 kits.
Anybody else interested? I promise to finish the 4 part windshield before I put my kit together (see windshield thread).
Hank

[Larry Lyons]

Re: Transponder in No Electrical System T-Craft

Although I have no need of a transponder, this is just to good of an idea to pass up. YES; of course I am interested in a kit or what ever you end up with. Larry

[astjp2]

Re: Transponder in No Electrical System T-Craft

I use a 7 Ah sealed lead acid battery that the FAA has approved for radio installation in my aircraft, I have a Microair 760 and an PS engineering 1000 intercom, I can fly for a week with out haveing to recharge the battery, I also stated that a spare batter would be in the aircraft in the event that became too low in flight. I mounted in the factory stated location infront of the seat in a billet aluminum tray and held down with 4each AN3-long enough bolts. It requires no vent and I use a cigarette lighter adapter to charge it through. You can get a 11Ah battery that is a little taller but you will need some real long bolts. I could probably dig up my fieild approval, 337 if it needed.
Tim

[OldBits2]

Re: Transponder in No Electrical System T-Craft

Hmmm,

Been associated with an IA & AP who has done this many times with simple references to AC43.13-1b AND -2a. His take is that if you install equipment that is FAA-TSOed, installed per the manufacturer' data, and per various specific AC 43.13 references, you are using approved data, and there is no 'field approval' required from the FAA.

Said he got that information in standards meetings with Washington FAA types. Has been filling out 337's like that and doing the signoffs for years with NO repercussions or problems. He is doing a radio/transponder/encoder for a Luscombe right now and says he is using those guidelines. Same as installation in a glider.....

FWIW, the Encoder must be hard plumbed AND TESTED in a correlationand static system test of that airplane. Therefore you can have a portable radio, but not a portable transponder with an encoder.

More info call Doug at 602-790-7240

[DanBrown]

Re: Transponder in No Electrical System T-Craft

My understanding is that the complete static system check is required for IFR certification of the installation. For VFR flying, the older Tcrafts were certified without a static system, so that the encoder can be open to the cabin air -- which allows for a protable installation.

[Forrest Barber]

Re: Transponder in No Electrical System T-Craft

Here in CLE FSDO area, they have approved many "portable" installations for hot air ballon & glider. Self contained & battery powered. Yes they have to be certified to a particular aircraft. WE are going to do one this Spring.

[Hank Jarrett]

Re: Transponder in No Electrical System T-Craft

We need a design so we can kit these things! All the "low and slow" guys I have talked to think the idea is great for those occasional flights through the FAA Black Holes".
Hank

[rdwater]

Re: Transponder in No Electrical System T-Craft

Jim Weir sells kit transponders/encoders (and lots of other things) at very reasonalbe prices. See:

http://www.rst-engr.com/index.html

He also has information about getting these homebuilt electronics packages approved into certified aircraft. See here:

http://www.rst-engr.com/rst/support/APNOTE_01.pdf

I haven't done it, but am looking into it.

Bob