owner produced parts

[Capt. Geoffrey Thorpe]

http://www.straightdope.com/columns...-many-angels-could-dance-on-the-head-of-a-pin

 

[peter-h]

Are there any absolutely prohibited owner produced parts?

For example could you make your own crankshaft?

Your own VHF radio?

 

[JHW]

Are there any absolutely prohibited owner produced parts?

For example could you make your own crankshaft?

Your own VHF radio?

for certain, commonly available parts line AN hardware etc are a no-no. But a radio ? Sure, in fact there used to be someone (maybe still is) selling kits to build your own audio panel / MB receiver and other avioics

 

[Tom-D]

for certain, commonly available parts line AN hardware etc are a no-no. But a radio ? Sure, in fact there used to be someone (maybe still is) selling kits to build your own audio panel / MB receiver and other avioics

You are talking about RST, he is alive and well here on the page. I had 6 of his head sets and they were great.

 

[kontiki]

Show me the rule????

At an airline certain policy manuals are approved by the FAA as the certificate holder's means of complying with part 121 rules.

There is no FAR rule that explicitly says how owner/operator parts are marked, but we do have rules in the policy manual that is approved by the FAA, that dictate how parts we manufacture here are marked.

Thats why I described the environment I was talking about. There are some differences.

Notwithstanding that, I believe if you manufacture a rib for a Cessna 172 and marked it with a Cessna P/N you would probably have just manufactured a bogus part.

 

[Tom-D]

At an airline certain policy manuals are approved by the FAA as the certificate holder's means of complying with part 121 rules.

There is no FAR rule that explicitly says how owner/operator parts are marked, but we do have rules in the policy manual that is approved by the FAA, that dictate how parts we manufacture here are marked.

Thats why I described the environment I was talking about. There are some differences.

Notwithstanding that, I believe if you manufacture a rib for a Cessna 172 and marked it with a Cessna P/N you would probably have just manufactured a bogus part.

You got that right. the rest is a personal opinion.

 

[kontiki]

You got that right. the rest is a personal opinion.

I don't know if your Ahaa! moment is anything more than what you read into my post.

And to be honest, I don't really know if there is an FAR that dictates how parts are marked. It's really irellevant when I'm working under 121 policy.

When you work under an operators certificate and the certificate holder's compliance policy manual is approved by the FAA, and the policy (and FARs) require you to follow the policy, then violation of the policy is usually interpreted as a legal fitness problem.

There are places in CFR Title 14, that do define parts manufacturing rules. It's been a while since I have looked them. If I think of it, I'll check my notes tonight. Most of the parts manufacturing issues I've seen involve STCs (the STC holder being the OEM) and getting PMA assist from a MIDO for another party to manufacture the mod kits.

Again, WORKING IN A PART 121 environment we can actually farm out the manufracture of parts WE(?) make to companies that have been audited to meet QA standards to manufacture on our behalf as if the work was done in one of our on site shops.

So some specially approved vendors can make our parts like it was done on site, but a part 145 repair station fixing our airplanes that does not have that special approval can make repair parts, but cannot make parts identified in an STC mod kit because they they are not one of those specially approved vendors.

Like all of this stuff, it's not universally black or white across the spectrum. A lot of what you can do is determined by what part of the FARs you work under.

Too may people try to formulate broad one size fits all models for how things are done in aviation. Move from one area or part of the FARs to another and the underlying assumptions do change.

This is before the influence of opinionated interpretations come in.

 

[Tom-D]

I don't know if your Ahaa! moment is anything more than what you read into my post.

And to be honest, I don't really know if there is an FAR that dictates how parts are marked. It's really irellevant when I'm working under 121 policy.

When you work under an operators certificate and the certificate holder's compliance policy manual is approved by the FAA, and the policy (and FARs) require you to follow the policy, then violation of the policy is usually interpreted as a legal fitness problem.

There are places in CFR Title 14, that do define parts manufacturing rules. It's been a while since I have looked them. If I think of it, I'll check my notes tonight. Most of the parts manufacturing issues I've seen involve STCs (the STC holder being the OEM) and getting PMA assist from a MIDO for another party to manufacture the mod kits.

Again, WORKING IN A PART 121 environment we can actually farm out the manufracture of parts WE(?) make to companies that have been audited to meet QA standards to manufacture on our behalf as if the work was done in one of our on site shops.

So some specially approved vendors can make our parts like it was done on site, but a part 145 repair station fixing our airplanes that does not have that special approval can make repair parts, but cannot make parts identified in an STC mod kit because they they are not one of those specially approved vendors.

Like all of this stuff, it's not universally black or white across the spectrum. A lot of what you can do is determined by what part of the FARs you work under.

Too may people try to formulate broad one size fits all models for how things are done in aviation. Move from one area or part of the FARs to another and the underlying assumptions do change.

This is before the influence of opinionated interpretations come in.

 

[VanDy]

Show me the rule????

There is no 'rule' but there is guidance in the form of AC43-213, that says there is no rule, does this answer the question?

​

(4)​

​

[FONT=Times New Roman,Times New Roman][FONT=Times New Roman,Times New Roman]Maintenance providers, including owners and operators, fabricating aircraft parts to be consumed during maintenance and alteration should clearly identify those articles with an additional permanent and legible marking. [/FONT][/FONT]
[FONT=Times New Roman,Times New Roman][FONT=Times New Roman,Times New Roman][/FONT][/FONT]​

it also states in the beginning of the AC

​

2. APPLICABILITY.
a. Audience. [FONT=Times New Roman,Times New Roman][FONT=Times New Roman,Times New Roman]This AC provides guidance to all persons performing maintenance, alteration, and fabrication, including the fabrication of owner- or operator-produced parts.
[/FONT][/FONT]
b. Not Mandatory or Regulatory. [FONT=Times New Roman,Times New Roman][FONT=Times New Roman,Times New Roman]This guidance is neither mandatory nor regulatory in nature and does not constitute a regulation. It describes acceptable means, but not the only means, for marking and re-marking parts, identifying major repairs, major alterations, and fabrication, including the fabrication of owner- or operator-produced parts. Terms such as "should," "may," and "must" are used only in the sense of ensuring applicability of this particular method of compliance. While these guidelines are not mandatory, they are derived from extensive Federal Aviation Administration (FAA) and industry experience in determining successful compliance with the applicable regulations. [/FONT][/FONT]

​

​

found this little tid bit interesting as well. I didn't look so far to see what the 'current legal rulings' were though. It reads to me that if it looks like a part, smells like a part, and fits like a part

(1) In accordance with current legal rulings, operators that do not have their own FAA-approved maintenance programs may still determine that an article is in an airworthy condition in the absence of identification data. This would normally require an inspection by a person authorized to perform maintenance or preventive maintenance under § 43.3.
(2) If the owner or operator elects to re-identify a part or to have additional identification information added to its parts during maintenance, it should accomplish this in accordance with the manufacturer’s manual or the maintenance provider’s procedures

and this little note at the bottom.

​

NOTE: A certificate holder who desires to sell his or her fabricated parts separately (i.e., outside the course of performing maintenance or an alteration) must obtain a PMA (refer to part 21).

 

[Tom-D]

Quote:
(1) In accordance with current legal rulings, operators that do not have their own FAA-approved maintenance programs may still determine that an article is in an airworthy condition in the absence of identification data.

Who would be required to have their own "FAA approved maintenance Program"

Part 91 operators ??

Good piece of home work by the way.

 

[Tom-D]

Where would I gain approval to manufacture a fuselage skin for a C-170? They have no maintenance manual, or a structural repair manual.

 

[VanDy]

Quote:
(1) In accordance with current legal rulings, operators that do not have their own FAA-approved maintenance programs may still determine that an article is in an airworthy condition in the absence of identification data.

Who would be required to have their own "FAA approved maintenance Program"

Part 91 operators ??

Good piece of home work by the way.

wouldn't part 91 operators fall under the 'do not have their own FAA-approved maint...' but i did a little more thourough reading and agree with you, although it did sound good!
that was

 

[Tom-D]

wouldn't part 91 operators fall under the 'do not have their own FAA-approved maint...' but i did a little more thourough reading and agree with you, although it did sound good!
that was

yes. Part 91 operators are governed by 91,401

 

[VanDy]

Where would I gain approval to manufacture a fuselage skin for a C-170? They have no maintenance manual, or a structural repair manual.

if no other guidelines, AC43-13 considers it a repair.

e. Repair of Damaged Skin.​

​

In cases
where metal skin is damaged extensively, repair
by replacing an entire sheet panel from
one structural member to the next. The repair
seams are to lie along stiffening members,
bulkheads, etc.; and each seam must be made
exactly the same in regard to rivet size, splicing,
and rivet pattern as the manufactured
seams at the edges of the original sheet. If the
two manufactured seams are different, the
stronger one will be copied. (See figure 4-16​

for typical acceptable methods of repairs.)

 

[kontiki]

Tom,

CFR Title 14 PART 21— is entitled (are you ready) CERTIFICATION PROCEDURES FOR PRODUCTS AND PARTS

You will be a better man after reading all of this. Have fun.

 

[peter-h]

if no other guidelines, AC43-13 considers it a repair.

Why would 43-13 cover a re-skinning, but not e.g. the fabrication of a bulkhead?

 

[Tom-D]

Each Cessna skin has a part number, they are listed in the Illustrated Parts breakdown.

but in the entry it says " Manufactured in the field from .025" 2024-T3"

there is your authority to make the part.

Later versions of the 100 series cessnas have a structural repair manuals that will give you the same authority.

The AC 43-13 is not authority to build any thing, It is acceptable data to gain field approval for major repairs on aircraft that have no supporting publications or manufacturers support. It does not apply to any aircraft with manufacturers manuals.

 

[peter-h]

It does not apply to any aircraft with manufacturers manuals.

Do you mean that "It does not apply to any aircraft with manufacturers manuals for the particular part"?

I think what you are saying is that re-skinning can "just be done", whereas doing something IAW 43-13 needs a 337 field approval sent off and approved before commencing the work - correct?

Is that true even if the fabricated bulkhead is provably identical to the original?

What if it is a non structural part e.g. a bracket holding some cabling?

 

[Tom-D]

Do you mean that "It does not apply to any aircraft with manufacturers manuals for the particular part"?

I think what you are saying is that re-skinning can "just be done", whereas doing something IAW 43-13 needs a 337 field approval sent off and approved before commencing the work - correct?

Is that true even if the fabricated bulkhead is provably identical to the original?

What if it is a non structural part e.g. a bracket holding some cabling?

If you are working on any aircraft that is not supported by the manufacturer with publications no matter how old it is. the 43-13 can be used as the maintenance manual. Plus it can be used as approved data to gain approval for major repairs to that aircraft.

Example, My 1937 Fairchild had a maintenance manual written and approved by Fairchild in 1937. Thus I could not quote the 43-13 for major repairs.

Many old aircraft have no such manuals, to repair them you can quote the 43-13. in block 8 of the 337.

 

[Tom-D]

I think what you are saying is that re-skinning can "just be done", whereas doing something IAW 43-13 needs a 337 field approval sent off and approved before commencing the work - correct?

Pretty close,,

it really depends upon if we are talking about a major repair, or regular maintenance.

the skin on a 170 can be replaced as a log book entry because we can manufacturer a skin as allowed by the manufacturer, and does not require a field approval as a major repair.

When you make a repair, or replace a part such as a bulkhead where the manufacturer has not given us the authorization to manufacture. Then we must treat that repair as a major repair, and gain authorization by a pre-approved field approval. And then make that part under the guidance of AC43-18.

When you manufacturer that part, you must duplicate it exactly and be able to prove it, because that is what owner produced parts is all about. Duplicating the part exactly, and being able to prove it.

 

[peter-h]

Would such a MM cover every aspect of the aircraft?

For example, my TB20 is "supported" with a MM which covers some aspects, and also Socata publish CMMs (component maintenance manuals) for certain things e.g. landing gear gas struts which, AIUI, would be illegal to service in the field without a CMM.

But no manual will cover everything.

I see 43-13 used for new aircraft e.g. if you install an Avidyne TAS 605 TCAS system which comes with an AML STC, the STC covers the basic system but the antenna installation is covered by 43-13. The resulting 337 is sent to Oklahoma for filing - it is not a "field approval".

 

[Tom-D]

What if it is a non structural part e.g. a bracket holding some cabling?

To me, that is a minor repair, and requires an entry in the maintenance records only.

 

[Tom-D]

Would such a MM cover every aspect of the aircraft?

For example, my TB20 is "supported" with a MM which covers some aspects, and also Socata publish CMMs (component maintenance manuals) for certain things e.g. landing gear gas struts which, AIUI, would be illegal to service in the field without a CMM.

But no manual will cover everything.

I see 43-13 used for new aircraft e.g. if you install an Avidyne TAS 605 TCAS system which comes with an AML STC, the STC covers the basic system but the antenna installation is covered by 43-13. The resulting 337 is sent to Oklahoma for filing - it is not a "field approval".

"Install" is the key word, you are modifying the aircraft, under the rules given us that requires either a field approval, or an STC.

To gain that field approval you can use the data in the 43-13.2b
1. PURPOSE. This advisory circular (AC) contains methods, techniques, and practices acceptable to the Administrator for the inspection and alteration on non-pressurized areas of civil aircraft of 12,500 lbs gross weight or less. This AC is for use by mechanics, repair stations, and other certificated entities. This data generally pertains to minor alterations; however, the alteration data herein may be used as approved data for major alterations when the AC chapter, page, and paragraph are listed in block 8 of FAA Form 337 when the user has determined that it is:
a. Appropriate to the product being altered,
b. Directly applicable to the alteration being made, and
c. Not contrary to manufacturer’s data.