Is the 1320 STC Dead?

I’m not sure, but I think the upgrade is outlined in TCDS 787 meaning no approval is required, just a 337 is submitted. Maybe an expert here can tell us the procedure. It was very common in the past, before the 2004 sport pilot rules gave it the kiss of death.

The only possible drawback I can see is getting an approval from the local FSDO. From what I've been hearing there are some that are loath to approve 337s.

Yeah, I don’t get it. Everybody was all over the 1320 STC but I don’t see as much interest in the upgrade. I guess part of it is cultural - for 20 years “415D” was a red flag - a sport pilot couldn’t fly it. But now they are an option. My 415C had all the upgrades necessary to become a D but the paperwork had never been filed and the elevator travel was still 13°. If I still owned it I would think hard about filing the paperwork.

I brought this up over a year ago on one of the Facebook groups and didn't really get much input or excitement about it. At some point I'll likely go ahead with the C to D conversion, given how often I'm looking for weight-saving options (like the EarthX battery STC).

One thing I'm watching at the moment is if there is more demand for a C or D, or if it affects [eventual] resell value or interest. There's a very good chance I'm just over thinking it, so it's just a matter of time.

I brought this up at the last convention and was surprised by the lack of excitement about this. Since MOSAIC now lets someone flying as a sport pilot legally fly an Ercoupe 415D, why wouldn’t I convert my C to a D and get 80 additional pounds?

Consider this:

1320 STC - I have to make sure the orifices in the oleos are correct. I must have the ¾” trim tab. My elevator up travel must be limited to 9°. When all is done, my new gross weight is 1320 pounds. 

Upgraded to D - I have to make sure the orifices in the oleos are correct. I must have the ¾” trim tab. My elevator up travel must be limited to 9°. AND the sheet metal directly over the cowl tank must be stainless steel. When all is done, my new gross weight is 1400 pounds. 

So the pro of upgrading to a D is an additional 80 pounds of legal gross weight and the con is the cost of replacing the skin over the cowl tank with stainless steel. 

The con of the STC is its cost. The conversion to a D model is by 337.

Which method would you choose to add the needed pounds to the legal weight? I’d go D conversion without a doubt. And now when shopping for a plane I would definitely consider D models - even prefer them!

If there is a good reason to go the STC route that I’ve overlooked, please let me know! And I know that 9° of up elevator requires faster landings. You can always go with a split elevator. But the limitation applies to both of these solutions, so it doesn’t matter.