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Designer approval

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p.mulwitz(at)worldnet.att
Guest

Posted: Thu Jul 20, 2006 2:06 pm Post subject: Designer approval

Hi Randy,



I think the truth is somewhere between the two extremes of requiring 

designer approval and not requiring it.  I believe kit builders are 

indeed the manufacturers of their planes and have final say on all 

things.  On the other hand, when building a kit plane or scratch 

building to some other designer's prints it makes sense to ask the 

designer if changes you are making will keep the overall result 

within the designed limits.  This may not be necessary for little 

changes like the ordinary procedures for fixing small errors, but 

when it comes to major structural changes like splicing a spar then 

it makes a lot of sense to get designer review of the change.



In the end it is the builder who will live or die with the results of 

changes.  I guess that means it is optional to seek approval, but 

prudent in some cases.



Best regards,



Paul

XL fuselage



 	  Quote: 	
		  Hummm.. I had no idea with kit built planes that you had to have the 

designer's approval... When I asked a while back about bolt torque 

specs, I was told that I was the manufacturer and could build/torque 

them anyway I wanted...

So, I'm assuming any deviation in plans should have to have the 

original designer's approval??



Just curious....


	


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randy(at)shadycreekoutlaw
Guest

Posted: Thu Jul 20, 2006 3:27 pm Post subject: Designer approval

Hi Paul,



Let me back up here a bit...  I think some people on the list took my 

remarks as a challenge..etc.  I was in a round about way asking a question 

about FAR approval, since I've not crossed that bridge yet and hope to in 

the future...not so distant I hope.  I just wasn't aware that for a 

deviation from plans, that your plane, might get "turned down" on inspection 

just for "not being by the plans", regardless of whether or not the change 

was aircraft worthy or not.



I have been under the impression that if you referred to the FAA 

publication, Acceptable Methods Techniques, and Practices: AIRCRAFT 

INSPECTION AND REPAIR AC 43.13-1B, that you should be able to "design" 

design your own changes, modifications, additions, subtractions..etc., 

without disapproval from the FAR...  That was the point/question I was 

trying to arise...



Thanks and peace everyone,



Randy



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zodierocket(at)hsfx.ca
Guest

Posted: Thu Jul 20, 2006 4:13 pm Post subject: Designer approval

Randy, please remember I am a Canadian and deal with cdn rules. There

are two points to get straight in this post, designer and manufacturer.

You are in fact the manufacturer of a Zenair design plane.If you wish it

to remain a Zenair design ( Chris Heintz) then you need approval for all

structural modifications. IF you do not get signed confirmation of a

structural change from Chris then you are now a designer and must

consider your plane a new model and must provide all testing showing

structural integrity and must submit all design forms to the proper

authorities. Now comes the real fun, a plane designed by Zenair ( Chris

Heintz) can be easily insured. I'm betting that a Randy design will have

difficulties and excessive expenses involved. For the rest please note,

that only a plane built to Zenair's designs, or modifications signed off

by the designer can be legally insured as a Zenair product. This is an

out that insurance companies can use in order to not have a payout, they

will even call in an inspector with explicit instructions to look for

modifications. Cosmetic changes are not applicable to the above

statement only structural, I believe Chris blesses making the plane your

own, just don't change his design. 



cdngoose

Zodiac 601XL C-GOXL, CH701 just started

www.ch601.org / www.ch701.com / www.Osprey2.com



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randy(at)shadycreekoutlaw
Guest

Posted: Thu Jul 20, 2006 4:47 pm Post subject: Designer approval

Ah ha!  That's the answer to my question: "Cosmetic changes are not 

applicable to the above

statement only structural"



Thanks,



Randy

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randy(at)shadycreekoutlaw
Guest

Posted: Thu Jul 20, 2006 4:47 pm Post subject: Designer approval

Ah ha!  That's the answer to my question: "Cosmetic changes are not 

applicable to the above

statement only structural"



Thanks,



Randy

Do Not Archive



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p.mulwitz(at)worldnet.att
Guest

Posted: Thu Jul 20, 2006 7:41 pm Post subject: Designer approval

Hi  Randy,



I am not an expert on interpretation of FARs, but I do have an idea 

that might be interesting for this line of conversation.



I don't think the FAA inspectors are in the business of determining 

how safe your airplane might or not be.  That is, in the case of an 

experimental - Amateur Built airworthiness certificate.  I have been 

led to believe the general idea behind the inspection for this kind 

of certificate is more about the paper work than the airplane.  They 

want to know you really built the plane or at that least it wasn't 

built by professional mechanics.  This is not much of an issue for a 

Zodiac or 701 but can be more of an issue when you get to really high 

performance expensive planes.  They also want to make sure all the 

paper work is properly filled out and then they must issue 

appropriate flight restrictions for your new plane.  The working 

assumption is you can kill yourself any way you want, but the 

government is  here to protect the general population from your crazy 

idea of flying an airplane you built in your garage.  After you have 

flown off the 40 hours over no-mans-land then they will let you fly 

it around as if it were a safe airplane.



The exception to this rule seems to be the E-LSA category of 

airworthiness certificate that takes effect after January 31, 

2008.  I haven't studied the wording of the FARs but the general idea 

is it must be exactly like the S-LSA it is patterned after.  In this 

case, I don't know how they determine whether or not there are 

deviations from the design but you aren't supposed to make any.  Of 

course, nobody knows how this will be implemented since it won't be 

done for a couple of years yet.



I hope this helps a little.



Paul

XL fuselage



 	  Quote: 	
		  Hi Paul,



Let me back up here a bit...  I think some people on the list took 

my remarks as a challenge..etc.  I was in a round about way asking a 

question about FAR approval, since I've not crossed that bridge yet 

and hope to in the future...not so distant I hope.  I just wasn't 

aware that for a deviation from plans, that your plane, might get 

"turned down" on inspection just for "not being by the plans", 

regardless of whether or not the change was aircraft worthy or not.



I have been under the impression that if you referred to the FAA 

publication, Acceptable Methods Techniques, and Practices: AIRCRAFT 

INSPECTION AND REPAIR AC 43.13-1B, that you should be able to 

"design" design your own changes, modifications, additions, 

subtractions..etc., without disapproval from the FAR...  That was 

the point/question I was trying to arise...



Thanks and peace everyone,



Randy


	


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steveadams

Joined: 10 Jan 2006
Posts: 191

Posted: Fri Jul 21, 2006 11:31 am Post subject: Re: Designer approval

Unless you specifically point it out to the inspector I don't think 99% of them would know if you made even a major change in the design. They are not inspecting the design of your plane (at least in the US), and most will not even look at your drawings. They are ensuring that you built it within the scope of the amateur built category and that the general construction practices meet the standards for acceptable methods and techniques. There is no requirement for Zenair to do the type of structural testing that some have mentioned, let alone any requirement for a builder who modifies the design to do so. With that said, I am not advocating making modifications to the design as I happen to believe that CH is a pretty brilliant man when it comes to aircraft design and I built my plane strictly by the plans.  It's not perfect, no design is. However, I don't think most of us have the knowledge or experience to fully comprehend why he did things the way he did, nor to what extent our proposed modifications will effect the structure and flying characteristics of the aircraft as a whole. It would be smart to consult Zenair when considering making major changes, but it is not required and I doubt they would officially sign off on anything more extensive than fixing a cracked skin or an incorrectly drilled part anyway.

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Float Flyr

Joined: 19 Jul 2006
Posts: 2704
Location: Campbellton, Newfoundland

Posted: Fri Jul 21, 2006 4:37 pm Post subject: Designer approval

In the end it is the builder and his/her passengers who will live or die

with the results of changes and let's not forget the poor folks who might be

on the ground too.

Noel



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_________________
Noel Loveys
Kitfox III-A
Aerocet 1100 Floats

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