What are differences between minor change and major alteration

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dougmen99
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What are differences between minor change and major alteration

Part 21 define “minor change” to type certificate, and Par 1 defined “major alteration”
As far I know all major alteration is minor change to the type certificate. Is it correct?

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AskBob
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You could start a big war on this subject. It has been discussed and debated for as long as I can remember.

Just a few months ago Joe Hertzler wrote a in depth article on the subject. Check it out at:
http://www.amtonline.com/publication/article.jsp?pubId=1&id=1693

dougmen99
dougmen99's picture

It is a realy gook article. The main subject is differentt between a major alteration and a minor alteration.

Now I ask for diferent between Minor change to type design and major alteration.

bob.pasch
bob.pasch's picture

Let's make sure we're talking apples to apples, Doug. Part 21 is Certification Procedures for Products and Parts. Are you sure you're asking the right question? Be specific and tell us which "Part" you're looking at that has a Type Certificate?

dougmen99
dougmen99's picture

Yes, Let me explain a little more the subject

Part 21 define “minor change” as:
A “minor change” is one that has no appreciable effect on the weight, balance, structural strength, reliability, operational characteristics, or other characteristics affecting the airworthiness of the product. All other changes are “major changes” (except as provided in paragraph (b) of this section).

and Par 1 defined “major alteration” as:
Major alteration means an alteration not listed in the aircraft, aircraft engine, or propeller specifications—

(1) That might appreciably affect weight, balance, structural strength, performance, powerplant operation, flight characteristics, or other qualities affecting airworthiness; or

(2) That is not done according to accepted practices or cannot be done by elementary operations.

The question is whether a major alteration is considered a minor or a major change to type design?

n14ky
n14ky's picture

You can have a Major Alteration that is not a "Major Change in Type Design", and you can have a Major Alteration that is a "Major Change in Type Design". It all depends on the scope of the Major Alteration. Like so many things with the FAA, it's clear as mud.

The best tool I've found to help with this is Order 8900.1 Volume 4 Chapter 9 Figure 4-67. Where it drives you is if you have a Major Change in Type Design per 21.93(a) you will need to go the STC route. If it's not, then you have other options for approved data

Hope this helps.

David Schober

Helpful friend (not verified)
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http://www.faa.gov/regulations_policies/rulemaking/committees/documents/...

Page 15

The document is out dated but was the closet's thing I could find.

bob.pasch
bob.pasch's picture

Respectfully Doug, I would disagree with your statement. A "Major Alteration" is defined as an alteration not listed in the aircraft, aircraft engine, or propeller specifications—

(1) That might appreciably affect weight, balance, structural strength, performance, powerplant operation, flight characteristics, or other qualities affecting airworthiness; or

(2) That is not done according to accepted practices or cannot be done by elementary operations.

A “minor change” is one that has no appreciable effect on the weight, balance, structural strength, reliability, operational characteristics, or other characteristics affecting the airworthiness of the product. All other changes are “major changes”

The difference being Major Alteration MIGHT appreciably affect weight, balance, structural strength, performance, powerplant operation etc. whereas the minor change DOES NOT. Just my opinion!

Stacheair1
Stacheair1's picture

There is a very simple answer to this question major / minor alteration and it can be found in CRR 43 Performance rules. And we are not talking original certification under Part 21 that is a whole different subject that engineering would be involved in.

I think you are asking about maintaining the aircraft or article after it has been received and now is being maintained under part 43. This is where the performance rules come in play.

§43.13 Performance rules (general).
(b) Each person maintaining or altering, or performing preventive maintenance, shall do that work in such a manner and use materials of such a quality, that the condition of the aircraft, airframe, aircraft engine, propeller, or appliance worked on will be at least equal to its original or properly altered condition (with regard to aerodynamic function, structural strength, resistance to vibration and deterioration, and other qualities affecting airworthiness).

The bottom line is if you make and alteration “BETTER THAN” or “LESS THAN” the original or properly altered condition it’s a major alteration that is what part 43.13 indicates.

I think you are asking what would a minor alteration be. So if it is a minor alteration it would not be on an FAA form 337 since that is reserved only for major alterations and repairs. So to determine if it is not a major you should start with looking at CFR 43 Appendix A to Part 43—Major Alterations, Major Repairs, and Preventive Maintenance. This will provide a list of major alteration items. So if it is not listed here it “may” but not always be considered a minor. This is where us IA’s have to use our knowledge to make a call in some cases. There is no list of minor alterations so it will be a case by case call after checking CFR 43.13(b) and the appendix list.

AskBob
AskBob's picture

Here is what Cessna Aircraft says about the difference between Major and Minor repairs.

http://www.youtube.com/watch?v=Q18ZexYcQQQ&list=PLC6375F6DCDD364E5

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