If improperly done....What are we including with this statement on the major-minor determination? 1

[KirbyWan]

Howdy all,

So I've been wondering about this for years and have no good understanding. One of the determinations for major minor is:

IF INPROPERLY DONE, WOULD THIS ACTION APPECIABLY AFFECT AIRWORTHINESS?

I just don't get this question. If improperly done...anything could fall under this category. What are they including? Are there examples that could sum up what we should be considering? Is this some vague catch-all? Is there an FAA explanation? I tried to search, but I get swamped in references to major-minor that don't address this specific question.

Thanks all,

-Kirby

Kirby Wilkerson

Remember, first define the problem, then solve it.

 

[rb1957]

I guess I'd read it as "if improperly manufactured, and improperly inspected (so something poorly built escaped the factory) then would/could the likely effects/consequences be catastrophic" but in the mindset of CPR and major/minor I'd add "and would the later airworthiness standard reduce the chance of this happening, or reduce the consequences".

wow, such a question ! I guess if service history pushed for the later reg then there's a case to pick it up ?

"Hoffen wir mal, dass alles gut geht !"
General Paulus, Nov 1942, outside Stalingrad after the launch of Operation Uranus.

 

[IRstuff]

If improperly done...anything could fall under this category.

As with the original equipment, it has to be something that would cause the aircraft to not, or no longer, fly, or more importantly, bring the passengers back to the ground alive.

TTFN (ta ta for now)
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[WKTaylor]

I asked this same question of 'old gray hair engineers'... they almost to a man answered... Each design is different... so the answer is imbedded in this counter question...

Is 'IT' built per the drawing, maintained by the manuals and flown by the book?? Then, by definition it is... or is not... and do not necessarily compare every aircraft to some 'mythical standards'.

I have learned this concept too over +45-Yr career... AND IT CAN BE challenging and MADDENING. For instance old Boeings do not resemble new Boeings... and likewise older and newer Lockheed and Douglass aircraft differ vastly from each other... and standards were very different.

Regards, Wil Taylor
o Trust - But Verify!
o For those who believe, no proof is required; for those who cannot believe, no proof is possible. [variation, Stuart Chase]
o Unfortunately, in science what You 'believe' is irrelevant. ["Orion", HBA forum]
o Only fools and charlatans know everything and understand everything." -Anton Chekhov

 

[RoarkS]

Majors are listed in

FAR 43 appendix A.
(a) Major Alterations
(b) Major repairs

If it's not listed it's a minor.

 

[MNLiaison]

Kirby,

2001 ARAC Committee discussion of origin and possible meaning of 'improperly done' and 'appreciably affect'. See link.

Aviation Rulemaking Advisory Committee, Air Carrier/General Aviation Maintenance Issue Area Clarification of Major/Minor Repairs or Alteration Working Group Task 1 – 14, CFR Chapter 1

Regards

 

[KirbyWan]

MNLiaison,

Thank you! That is exactly what I was looking for. That's a great discussion of why the wording is as it is and suggestions for clarifying.

-Kirby

Kirby Wilkerson

Remember, first define the problem, then solve it.

 

[WKTaylor]

Interesting question.

I'm considering reformulating/asking my folks to think about this in relation to the work we do on the antique [waaaaaay-post-production] jets in our care... and then ask the other team, who work on new production jets... the same question.

The antique jets seem to have a higher tolerance for various forms of 'damage' and system issues... whereas the new production aircraft are designed with 'lower margins' and strict 'damage' and system operating limits.

Regards, Wil Taylor
o Trust - But Verify!
o For those who believe, no proof is required; for those who cannot believe, no proof is possible. [variation, Stuart Chase]
o Unfortunately, in science what You 'believe' is irrelevant. ["Orion", HBA forum]
o Only fools and charlatans know everything and understand everything." -Anton Chekhov

 

[debodine]

RoarkS is spot on for 14 CFR Part 43, Maintenance. However, for those of us in the Transport Category type design/alteration world, 14 CFR Section 21.93 says this:

"...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...'."

It matters a lot whether you are in the "restore/maintain airworthiness" world or the "change the type design" world.

So in the maintenance domain, it is only major if it is listed as major. In the type design change domain, if you can't justify fitting it into the minor category, it's major.

Somewhat like insurance policies. If it isn't listed as excluded, it's included. OR if it isn't listed as included, it's excluded.

 

[mfgenggear]

That in my opinion is a complex and not as simple as it seem

A major could or can be a repair. That alters the certification.

Minor could be or can be a rework that
Restore a part that is not a repair
And meets the original certified design.

In my line of work designers can make design changes that does not affect fit, form or function. And can be a minor change.

If a design changes the configuration
It may or may not require FAA approvals and recertification.

 

[mfgenggear]

In my case gear boxes have so many hour of run time cycles, with out incidents.
And are certified by the FAA.
And if there is a major change then recertification is required.

If a part has an issue it has to be determined at MRB, if it affects fit form or function. If does it can be scrap.

 

[mfgenggear]

An other example if improperly done and is a major change. Would be an illegal repair.

 

[RoarkS]

"rework" is a manufacturing term. Go check out my MRB cage.
To restore XXX to its original design is a repair. Talk to a 145.
If you have MFG or PMA, you can restore it and throw all the paper work out and make it a new part (if you have that approved procedure)

I agree with Debodine... I'm redesigning an STC. There is a material change that ACO is requiring a new material burn test. **if** it wasn't for that "Operational characteristic" it would have been a minor change we would have just done a drawing revision.

PER: § 21.93 Classification of changes in type design.

(a) In addition to changes in type design specified in paragraph (b) of this section, changes in type design are classified as minor and major. 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).

PER FAR 1.1
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.

Major repair means a repair:

(1) That, if improperly done, 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.

Yeah... it's kind of a catch all but check this out...

Then Go see Order 8300.16A 5b

The use of the terms “major” and “minor” are sometimes inappropriately
applied or misunderstood. A major change in type design can be approved only by an ACO or an
ODA holder with Supplemental Type Certificate (STC) or type certificate (TC) authorization.

A major alteration requires the use of FAA-approved technical data. Minor alterations only
require data that is acceptable to the FAA. During an evaluation, an anticipated major alteration
may be subsequently classified as a major change in type design, and thus would require
application for an amended TC or STC.

And finally... Look at it from the perspective as an enforcement action from the FAA. They have to use the "Major Repair and Alteration Data
Approval Job Aid" published through the AFS-300 office. Go find what you need.

 

[mfgenggear]

Rhetorical question.
Part is inspected, the part is out of tolerance.
Question can it be reworked , yes
Mrb engineering disposition is
Return for rework to engineering drawing..

Partt is is inspected, and is out of tolerance.
Can it be rework to engineering drawing, no
MRB engineering deposition. Scrap.

I worked in an mrb crib for general dynamics for f16 and atlas program
Rework is not a manufacturing term.

 

[mfgenggear]

Major and minor changes can apply to many different application for different products other than aircraft.

 

[RoarkS]

But you were the manufacturer. You were unable to rework the part... it's no longer a part per GD part definitions.

"rework" is not a FAA term. It is only internally defined by a manufacturer or PMA holder per their approved QMS.

EDIT: True. The catch all there is "article". But I assume we're talking about FAA regulated things using their FARs.

 

[mfgenggear]

PMA is a FAA approved after market part.
Correct.
If the part does not meet the engineering drawing. PMA has engineering deposition.

Now as far as general dynamics it depended on government contract.
For example the F16 required FAA approval for major changes. GD Engineering has to submit the EO for their approva.if it was a major change. Minor change did not require FAA approval.
Atlas program was a commercial and GD had full atonement.

There was government contracts GD had autonomy and did not require FAA approval

 

[mfgenggear]

And yes I degrees, it was an internal difinition

 

[SWComposites]

Why would the FAA be involved with the F16? The FAA has been involved with military derivatives of commercial aircraft, such as the 767 tanker.

 

[mfgenggear]

Because if it was FAA certified part, back then may not be current. Also back the when they were called decass, were very involved. They are are called some thing else now. They giving GD warnings not following procedures. Standard sop as written.