On Thursday, May 16, 2019 at 7:58:33 AM UTC-7, Tango Eight wrote:
On Thursday, May 16, 2019 at 12:49:42 AM UTC-4, Darryl Ramm wrote:
On Wednesday, May 15, 2019 at 8:20:19 PM UTC-7, son_of_flubber wrote:
On Wednesday, May 15, 2019 at 7:49:31 PM UTC-4, Dan Marotta wrote:
For a Standard category glider it was a big pain to install and get the
documentation correct and approved.Â*

For me, the documentation was trivial. I made a logbook entry and got a PAPR https://adsbperformance.faa.gov/paprrequest.aspx (recommended but not required) The TT22 antenna got moved to a more optimal position further back in the fuselage, so I had got a fresh transponder compliance check (which was due anyways). My avionics tech looked over the installation that I did.


It was also very expensive

The TN72 including an interior mount antenna cost ~$400. I also bought a custom length antenna wire for the XPND for a few bucks. Craggy made the interconnect cable for me. I had a fun 5-6 hours doing the install. The transponder was installed by the previous owner.


WAAS GPS box is very large, nearly double the size of the XPND remote box.

The TN72 GPS box is smaller than the XPND remote box.Â*


Fortunately, there's plenty of room behind the Stemme's panel for the
hardware.Â*

No room left behind my panel, so I mounted a piece of plywood vertically behind my headrest on the turtle deck, and mounted the boxes to it. Provisions made to ensure air circulation. Space occupied is 2.5 inches front to back, 4" vertical, and full width of the turtle deck. Radio & vario speakers and a 'dashcam' are mounted to the same piece of plywood. I still have room on the turtledeck for a compression stuffsack of rain/cold/etc. gear, food, water for landouts.


I haven't had a "close encounter" since installing a
transponder about 7 years ago.Â*

As noted in my post above, one month after my install, I had one confirmed 'problem averted' with a GA airplane that could only 'see me' on their ADS-B-in screen. Better visibility to GA airplanes is the big win.

It's fantastic you both installed 1090ES out, and the point that a TN72 install is pretty easy is a great one... if anybody has a Trig transponder adding a TN72 should be easy.

But now what are you guys comparing? Dan was talking about a 2020 Compliant (aka SIL=3) ADS-B Out install in a type certificated glider, so the need for the fancier TSO-C145c TN70 GPS with it's extra space and cost (compared to a TN72 GPS).

Now that's being compared to a 2020 Compliant install in an experimental glider right? Hence the TN72, smaller size, lower cost and slightly easier process (no 337 submitted).

It's unfortunate that the ADS-B out install is different between a type certified and experimental glider, frustrating, it makes no justifiable sense and the extra cost/small hassle increase may affect adoption and overall safety. But that is how it is. We know it's more expensive, but the process to do this has some extra paperwork but should just not be daunting, and the install should not be technically challenging. Any A&P should be able to do that (should not need to be an IA)... obviously you want somebody who you trust to work on a gliders.

And a reminder you can use a TN72 in a type certified glider to do TABS (aka SIL=1) but not 2020 Compliance (SIL=3), that gets you everything except visibility to ATC via ADS-B (they still see you via SSR within SSR coverage) and does not get you any 2020 Airspace flight privileges (the remaining airspace that the glider/engine powered generator... exemption does not cover). You can also use the TN72 to do TABS if you have a TT21 but not TT22 in an experiential glider (2020 compliance requires a TT22).

Has anyone tried to get AOPA to do some advocacy for saner requirements for VFR only aircraft in general and standard airworthiness gliders in particular? There's no downside... even the FAA might have to admit that.

Evan Ludeman

The fat lady may have left the barn already, with 2020 being so close.

I had hoped that some organizations might look at this with an STC approach similar to the STC that use non-TSO instruments flight instruments in type certified aircraft. Both AOPA and EAA have been involved in those efforts..

e.g. https://www.aopa.org/news-and-media/...ilities-abound

https://www.flyingmag.com/non-certif...fied-airplanes (asks does not answer the ADS-B Question)

Larger avionics manufactures who manufacture existing TSO-C145c GPS sources may have a financially disincentive to not help here. It is 2020 regulations driving ADS-B Out demand, not a free market. Avionics manufacturers in the flight instruments and autopilot upgrade market are more incented to jump onto the non-TSO STCs and compete to win panel upgrade business in a more competitive open market environment. The glider community is pretty lucky that Trig has been focused where they are, and been just nice folks like helping the FAA develop the TABS TSO-C199 standard on one hand, working with Peregrine to get the TN70 STC available to glider A&Ps etc. Maybe being an OEM customer (not OEM) of GPS technology and a desire to sell more of their transponders provided some financial alignment for them.

In the parallel universe of UAT even uAvionix has gone the TSO route for their devices for install in type certified aircraft, and that's with having to develop STCs for actual installs anyhow. (they brag about how many aircraft are on their AML STC list for devices... actually being on the AML list becomes more of an issue once you get to more complex GA installs and IFR aircraft panels, and may be in part to placate GA repair shop concerns about say replacing a wing-tip or tail-light with a non-OEM device). I suspect it was quicker for uAvionix to just comply, develop the TSO and install STC than to try to develop a whole new STC approach for a non-TSO-C145c GPS source.