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.

 

[WKTaylor]

mfgenggear...

100% MIL derived Acft are certified thru DoD ONLY... starting with MIL-HDBK-516C AIRWORTHINESS CERTIFICATION CRITERIA.

MIL-Derivatives, that intend to use available civilian/commercial 'spares and services' MUST have joint FAA/DoD certification... which mandates maintenance/repairs/parts/etc in conformance with FAA approval for the unmodified part of the aircraft. For the MIL aspects of the SAME Acft, certification per MIL-HDBK-516 applies. I never wanted to be on those teams. EVER.

/NOTES1/
At some point... when the scale of 'original' aircraft parts are modified/altered 'beyond civilian compatibility', then DoD often assumes 100% of the certification and 100% of the logistics.
ON RARE OCCASIONS, certain FMS aircraft operators, insist on Civil Certification of a purely MIL Acft design type. What a pain... especially for a 65-YO USAF KC-135 Acft.

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

 

[mfgenggear]

Thanks for that clarification, like I said I been out of the loop, and forgetting things. Decas back thewas very involved

 

[debodine]

This may be a gross over-simplification, and I am open to correction by my peers. Admittedly my experience is in Part 25 Transport aircraft certification, so I am weaker in other Parts of the regulations. As I understand the issues about alterations and repairs, both major and minor, here is how I keep them straight in my mind.

Under 14 CFR Part 43
Alteration (Major and Minor)
Repair (Major and Minor)
No change to Type Design


Under 14 CFR Part 21 (certification for aircraft/products for Transport Category Part 25)
Type Design (Type Certificate)
Changes to Type Design (Amended Type Certificate, Supplemental Type Certificate, Amended Supplemental Type Certificate).

At least the above has been my experience in our organization.

 

[mfgenggear]

Has any one written a procedure on the specification given by by our fellow engineers.
Which generally would be a quality engineers
Responsibility. And incorporated into AS/ISO 9100
Certification. This is what General Dynamics was getting gaged for not following the procedure
For the specifications.

 

[WKTaylor]

Note RE The aircraft I work on.

+10-years ago the SRM T.O.s for my 'primary aircraft' were entirely reorganized, since the 5-base documents had each gotten too big and were disorganized. They decided that individual T.O.s would be written along major structural elements: [general structural practices, procedures, corrosion prevention, etc; fuselage; wings; stabilizers; landing gear attachment structure; APU system; engine pylons-cowlings-fitting; MAJOR/depot/complex structure repairs; Interiors [flooring, seats, insulation, paneling, toilet, etc].

Prior to the re-write I strongly recommended that each T.O. be broken-down to three major subdivisions... all primary/flight-critical structure [up front]; and all secondary structure [towards the back]; and all complex depot [non-field-level] repairs. Essentially 3-books in-one-book. This three-tier T.O. layout would have eliminated all DOUBT regarding 'structure type/criticality' when reading the document, IE: primary/major; secondary/minor; interface between the two; and Depot level major/complex Repairs. NOPE never happened... We still have engineers, planners, mechanics and QA confused/at-odds about what is flight critical; and what is 'NOT'.

The ONLY clue card that is really out there regarding all of this 'primary/major' and 'secondary/minor'... fly/no-fly... are detailed illustrations/part-listings for the aircraft-specific structural/mechanical/electrical repair document related to Aircraft Battle Damage Assessment and Repair [ABDAR]... ferry flights.

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

 

[mfgenggear]

Will
Lol we know a toilet is not critical well maybe if can't use the john.
But seriously.
I just saw a video the CEO of Boeing was being investigated by congress. For falsifying certifications. I know when I produce an aircraft gear for a critical systems. Let say PT6 engine gear box. We have a stack of paper work. Documenting every detail of Tha part.
Raw material to the finish product. With 100% mechanical inspection on critical dimensions.
Non destructive, heat treat certification all based on the specification on the drawings and the
Standard procedures based on as/iso9100.
And more to many to mention.
All get serialized.and parts marked.
And is put of flight worthiness.
In my day was critical flight safety .

 

[mfgenggear]

Will
I know an aircraft is way more complex and is not a simple as my example. And I over simplified.
I was very anal of parts that were flight critical. And I was very serious .
I had a 100% track record.

 

[kontiki99]

When I was in A&P school, back in the late 70's, and we talked about airworthiness the instructors told us that the FAA had never defined it. The word airworthiness has always been used in the recommended log sign off for an annual though. Over the years I kept an eye out for a definition and ultimately a definition showed up in CFR Title 14, FAR 3.5. I went back through the federal register and checked and it was published there sometime in 2005. I suspect there are advisory circulars on this.

To paraphrase 3.5, it's got to be in the approved configuration and maintained according to to prescribed maintenance program.

I see this being the configuration as defined by the TC, STCs, without any unapproved major alterations and repairs with properly maintained maintenance records.





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