Any Rans S-6 owners here?

A student bought a Rans S-6ES with a Rotax 912 and standard wing. I flew with his instructor for insurance requirements and he has been giving the owner dual in it since.

It was time for the first condition inspection and while in the shop compared the weight and balance to the build manuals.

The builder stated on the original application that the airplane had an empty weight of 733 lbs.
He set the gross weight at 1320 (LSA limit).

But in the kit manual I see a couple gross weights for the various engines with various wings.

For the Rotax 912ULS version with standard wing it lists a gross weight of 1010 LBS.

The owner called Randy Schlitter who was the original designer and he said it's fine you can operate up to 1500 lbs. He said that he designed the airplane for that as the gross weigh limit then LSA was adopted for less.

This seems very strange to me because the S-6 was designed well before LSA existed. April 1990 was when the ES version with the Rotax 912 was released. All of the build manual airspeeds and rough air penetration speed of 70 mph etc would be based on 1010 LBS if there was any engineering. IF operating as a standard experimental AB 500 lbs is a HUGE difference on a little light 2 place airplane. They just don't have those kind of margins built it looking at the size of the fittings and construction compared to regular airplanes in the same weight class.

Something does not seem right.

Isn’t that an Experimental, Charlie? Experimental Amateur Built.

With EABs, the builder can choose whatever gross weight they want and that becomes the official weight. They are they “Manufacturer”.

Somewhere I have a blurb from Richard Van Grunsven about “The Margin”. It’s great. He discusses engineering principles and how the engineer adds a “margin” for safety and how the builder should leave that margin in place bc it belongs to the Engineer. Hasn’t stopped guys who are building VANs aircraft from choosing their own GW however.

Found it..

Agreed the "Margin" should be there. Yes it is totally legal. Builder picked the gross weight.
But sadly the wing spars don't care about legality........

The build manual has 1010 lbs. No mention of anything beyond that.

I have a customer support question email into Rans so hopefully I'lll get some better info.

I suspect you will get a very conservative answer from Rans. They were the only kit maker in this class that was loathe to publicly agree to a slightly higher gross on floats.

So true. Nor does the tail care about legality.

The thing that seems to be reeling this practice in - at least with RV’s - is concern for liability. Peeps have realized that since they are the manufacturer, they are the ones on the hook if they sell the airplane and someone overloads and crashes it.

There is no preservation like self-preservation.

In my current role I get to cover this question very frequently.

The bottom line is the designer is the only person who can correctly answer questions about safe gross weight for the aircraft.

If the designer starts out very conservative in their estimates they may eventually increase the aircraft gross weight based on in-service experience. Sometimes the gross weight increase comes solely by dint of the designer finally having enough cash to carry out real loading tests. I know of one aircraft which received a very significant increase in gross weight because the designer finally TESTED the wing rather then going with conservative engineering estimates.

At the end of the day, Rans will have to answer the question, giving due consideration to the vintage of the kit from which the aircraft was built. Whatever their answer is becomes a safety recommendation in light of US regulations with respect to assignment of gross weight by the "builder". Still, I would hope that kit manufacturer's safety recommendation should carry a lot of weight (pun intended) in terms of how the aircraft is operated.

(Gross Weight limits for Amateur-Built aircraft in Canada don't come with the same "assign any gross weight you choose" freedom that is available in the USA - I'm mentioning this solely as a reminder to any Canadian builders who might stumble upon this thread in the future.)

I got a reply from Rans.

Charlie,

Randy is the one that would know! So, I'd say it's okay. I think that's what everyone else uses as well.

Thank you,

Michele “Shelly” Schlitter
Vice President | Sales Director

RANS Designs, Inc.
4600 US HWY 183 Alt
Hays, KS 67601
http://www.rans.com | http://shoprans.com

Technical Support Disclaimer: Technical advice or information provided by any personnel of RANS Designs Inc. in any form is to be considered reference advice or information and may require further validation by the builder, client, or end user. RANS Designs Inc. will not be held responsible for any loss or damage as a result of our advice or information supplied in any form.



Inquiry: Rans S-6ES 912 ULS standard wing gross weight
Message: Hello I am a mechanic performing a condition inspection on a S-6ES with 912ULS. The build manual shows a gross weight of 1010 lbs with the standard wing. The original builder used 1320 for a gross weight. It does have the black jury struts with the rear diagonal brace. The owner (not the builder) called spoke with Randy. He said it was ok for 1320 lbs but I just wanted to be sure. Thank You.

This is why I hate the experimental and LSA industry. A 30% gross weight increase is a HUGE change and this is the simplest of questions to try to verify it.

NO cares given or attempt to provide information.

This is a stock configuration long established design by a company that makes also SLSA Light Sport airplanes. All I need is some type of letter or reference to show the gross weight is allowable with the design of the airplane to cover my rear signing off the condition inspection.
The RANS website info shows 1320 lbs for the S-6ES. They do list it for the ELS but that is the current light sport version. But no idea if that is S/N specific or some other type of mod needed.





Thanks Michele.
Is there any service letter or bulletin I can reference to put with the airplanes logs showing 1320 lbs Gross weight is acceptable for the structure.
Thanks

Charlie

On Jan 27, 2025, at 10:36 AM, Michele Schlitter <michele@rans.com> wrote:
No, not that I'm aware of.


Michele “Shelly” Schlitter
Vice President | Sales Director



RANS Designs, Inc.
4600 US HWY 183 Alt
Hays, KS 67601
http://www.rans.com | http://shoprans.com

Technical Support Disclaimer: Technical advice or information provided by any personnel of RANS Designs Inc. in any form is to be considered reference advice or information and may require further validation by the builder, client, or end user. RANS Designs Inc. will not be held responsible for any loss or damage as a result of our advice or information supplied in any form.

Looks like you need to speak with Randy.
Michelle is just sales and doesn't understand your issue is my bet.

Yes that is the next to try.

As far as the laws of man - that question was already answered when the airworthiness certificate was granted. The builder declared a gross weight and the DAR at the time agreed.

As far as the laws of physics, it's a grey area. If you are not comfortable with it, don't do it.

But it's not in the purview of the condition inspection to modify the max gross weight or operating imitations.

Yes I understand my responsibility as the mechanic and the owner but since he is not the builder only a Student pilot and this is his first airplane I'm questioning how this is correct. Wings fall off or stay on is not determined by legality. Owner is a big guy . 18 gallons fuel and instructor doing instruction things.

I was burned by this type of thing before with an X-Air Hanuman. I bought the kit which was supposed to have 1320 gross weight. I Built the airplane and once flying I started to question some things. Like Stainless steel attach fittings for the wing struts. I finally got in touch with the designer in France and the importer Bill Magrini had lied. The gross weight was really 1179 lbs. My kit was shipped air freight on Air France flight so it was not an old one sitting in the US.

They still have gross weight confusion

Then the British did a static test on them where the airplane was flipped over and static tested instead of just testing the wing with strut bolted to a beam on the hangar wall. The fuselage cockpit cage collapsed below gross weight in compression from the strut loads!

The designer finally admitted to me that they made kit changes in India (Randkar was the company) but could not get permission to test fly. So they made the changes and waited for unknowing builder feedback of if the changes were successful or not.

Between this and the long history of Kitfox mods and other LSAs and ultralights we have tried I'm very suspect of the engineering on every one.

I think I'm at a loss here. Are you performing condition inspection or are you performing design recertification?

Since when condition inspection involves reviewing and questioning weight and speed limits set forth by the manufacturer of the airframe (aka the builder)?

Are you also retesting and validating speed markings on the AI? Are you checking stall horn activation at proper speed?

As far as the laws of man - that question was already answered when the airworthiness certificate was granted. The builder declared a gross weight and the DAR at the time agreed.

As far as the laws of physics, it's a grey area. If you are not comfortable with it, don't do it.

But it's not in the purview of the condition inspection to modify the max gross weight or operating imitations.