Gross increase with STOL?

JimC · #1 09-03-17, 08:42 PM

If you look at the old Robertson brochures, they claim a GW increase for A-E models. Is this a typo, or do you really get a GW increase? Can someone with one of those models actually confirm the increase?

Some posts on this site claim a 100lb GW increase with a Horton kit, some say there's no increase. Does anyone have the paperwork that shows the real answer?

http://www.337skymaster.com/messages...5&d=1240974251

hharney · #2 09-04-17, 11:43 AM

Jim

It would probably depend on how the STC was submitted. If the STC did not indicate a GW increase and a W&B sheet was not accounted for you would have to go back and re-submit the form 337. May have to get FSDO involved. I can't imagine anyone NOT taking advantage of this but stuff gets through the cracks

I am not aware of any GW increase with the Horton STOL system.

JimC · #3 09-07-17, 08:21 AM

I was wondering if anyone with a Robertson STOL could confirm that they actually did get a GW increase.

JimC · #4 09-28-17, 03:09 PM

I found at least one 337D that most definitely got a GW increase to 4700 lbs with a Robertson STOL. Landing weight was raised to 4465. The brochure only advertises a raise to 4630, but this one somehow got to 4700.

B2C2 · #5 11-22-17, 03:06 PM

I have a Robertson equipped 1969 T337D with the original STC paperwork. the differences in GW increase are for NA vs Turbo models.

NA GW is 4630
Turbo GW is 4700

This is true for all models A-G

for my aircraft all weight above 4500 must be carried as fuel, and max landing weight is 4465.

I can scan and post the full STC if you would like.

Ben

JimC · #6 11-23-17, 10:26 AM

A scanned copy of the STC would be much appreciated.

B2C2 · #7 12-07-17, 01:39 PM

Sorry for the delay. Here's the scanned document. Interestingly, I am apparently missing pages 3 and 4. These presumably cover the A and B models. I don't know why that is. This is what I have in my log books from when I purchased the plane and it starts with the 1967 models. Since mine is a 1969 T337D it is covered by whats in here. I also have the original Installation and Pilots Operating Handbook supplements for the Robertson STC.

B2C2 · #8 12-08-17, 01:30 PM

http://rgl.faa.gov/Regulatory_and_Gu...light=sa1627we

Here's a link to the FAA STC registry page which has the full text as a pdf

Ed Coffman · #9 12-12-17, 07:32 PM

We have a 70 E mode, before the robertson was added it was a 4400 lb max TO weight plane. After the the robertson was incorporated the max TO weight is now 4630.

JimC · #10 12-13-17, 09:22 AM

Ed, what's your empty weight?

Ed Coffman · #11 12-14-17, 10:51 AM

3072 1558 useful

JimC · #12 05-29-20, 11:01 PM

I bought a T337E, I can confirm my gross weight with the R/STOL kit is 4700 lbs (up from 4630lbs.) Landing weight is unchanged at 4400 lbs.

hharney · #13 05-31-20, 08:46 PM

Congrats Jim, glad you found one. Now the fun begins........