For the pro mechanics… What regulation prevents me from putting a Vetterman exhaust on a standard category Cub? Why wouldn’t it qualify as a minor alteration? What about adding a crankcase vacuum on my Cessna? It doesn’t seem to be a major alteration by definition of major, so why can’t I add one as a minor? I read on other sites how guys continue to think cowl louvers on a Cessna require an STC when it qualifies as a minor by FAA definition. Is there a regulation that limits such alterations other than the definitions of major and minor? Is it solely up to the IA who returns the plane to service?
Question on Regulations
- Thread starter stewartb
- Start date
wireweinie
FOUNDER
Palmer, AK
This is from FAR 43, Appendix A, definition of major alterations
(xii) Changes to the basic design of the fuel, oil, cooling, heating, cabin pressurization, electrical, hydraulic, de-icing, or exhaust systems.
You'd have to get past that line in any argument.
Web
(xii) Changes to the basic design of the fuel, oil, cooling, heating, cabin pressurization, electrical, hydraulic, de-icing, or exhaust systems.
You'd have to get past that line in any argument.
Web
Ken Robbins
Registered User
Petaluma, CA & Kasilof, AK
Still learning after 40 years as an IA, I take the approach that everything is major until I can prove it to be minor. This is my own mental starting point and as it was said "It's all up the the IA's interpretation.......until it isn't" and I had a poster child experience on that front. Installed a small composite fairing to clean up a P-210 cowl exhaust opening that had been butchered by well meaning folks trying to get a new tailpipe installed. An incident happened unrelated to the fairing and I was taken to task due to the fairing being STC'd to a different model aircraft to aid in cooling. I received counseling on my responsibilities as an IA and sent on my way. The discussion focused (my part) on the FAA major/minor flow chart. All roads led to minor but they said the chart is good until it isn't. The fact remained that the fairing was called a cooling aid.
I get along fine with the FAA and push back constantly when I don't agree but in this case, attorneys would have cast me a fortune and they were avoiding any talk of violation. Long and short was, I saved the owner from replacing an expensive cowl panel job and cost myself a bunch in lost shop time and aggravation.
You also have to factor in the local interpretations of your FSDO, like it or not.
Ken
I get along fine with the FAA and push back constantly when I don't agree but in this case, attorneys would have cast me a fortune and they were avoiding any talk of violation. Long and short was, I saved the owner from replacing an expensive cowl panel job and cost myself a bunch in lost shop time and aggravation.
You also have to factor in the local interpretations of your FSDO, like it or not.
Ken
And 14CFR 1.1 and 21.93 (major change in type design). Then go to AC 43-210A and use the flow chart there. Pretty much covers all the bases. I’ve taken to using the flow chart and anything that someone might question actually list the answer to each question that I applied. If ever questioned the response is that I used the regulations and FAA provided guidance to make the “minor alteration” determination. You would be surprised at how much stuff that FAA has insisted was a Mojor Alteration in the past when actually using the guidance is really minor alterations. Another option is to ask a DER to provide an 8110-3 for approved data. The DER handbook explicitly prohibits the issuance of an 8110-3 for minor repairs or minor alterations. If the DER says no, ask him to send an email. Now you have documentation from a DER that says it is a m8nor.
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frequent_flyer
Registered User
Arizona, USA
Where does FAA define "basic design". It must mean something other than "design" or the word "basic" contributes nothing to the requirement.
The term "basic design" is used in FAA_Order_8110.37F.pdf but is not defined there.
I assume that "basic design" is less implementation specific than "detailed design". If that's the case then how implementation specific is FAA "basic design" when used to determine whether an alteration has been made.
The term "basic design" is used in FAA_Order_8110.37F.pdf but is not defined there.
I assume that "basic design" is less implementation specific than "detailed design". If that's the case then how implementation specific is FAA "basic design" when used to determine whether an alteration has been made.
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hotrod180
FRIEND
Port Townsend, WA
Formandfunction
MEMBER
Precedence plays a part sometimes. If a minor modification has been stc'd the paper trail labels it major. Kinda like the visors that should be minor but faa considers major single handedly on a stc.
And I’d argue louvers are not a basic design change. Air goes in the top, comes out the bottom; adding a little more exit area doesn’t seem like a basic design change, but that’s just me…
cubdrvr
SPONSOR
YKN(mother city of the dakotas)
Not sure I understand. If there is an STC for a portable GPS mount will that require an STC for any mount? Or no other mount can be installed since there is an STC for one?
Formandfunction
MEMBER
Kinda,yeah. Faa considers anything stc worthy a major modification. Doesn't really matter if it makes sense,they just use paperwork as a concrete definition. I'm sure anyone could find holes and examples all over the place as screwed up as everything is,that's just the way they explained it to me.
Formandfunction
MEMBER
But I did recently use a piper service bulletin to replace aluminum wires with copper and bogart holds a stc on that. So I guess it's ok if piper says so.
EdH
Registered User
Alaska
They have issued STCs for tons of things that are generally considered minor alterations. Rosen Sunvisors are a perfect example. No one would ever consider them a major alteration, except for the fact they come with an STC. I recently installed a McFarlane flap upgrade kit on a 185 that came with an STC, but even the install instructions said it was not necessary and was a logbook entry only.
Generally, they will not issue a field approval if there is a similar STC, and will tell you to get the STC instead.
Like you said, doesn’t matter if it make sense. The FAA isn’t known for their consistency.
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The problem we have with STCs that would otherwise be a minor alteration has to do with parts production. Part 21 specifies that any part known to be sold and to be used on a certified airplane needs to be produced under a PMA. To get PMA, that part needs to have some “approved design”. Since things like sun visors and many other aftermarket things are not part of the Type Certificate, the only way the vendor can get PMA to comply with the 21.9 requirement is to get an STC to provide the “approved design” FAA screwed everyone when they implemented the PMA rule back in the late 1960s. Prior to that there was no need for certification of parts, it was just form, fit and function!
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Basic design of each of the systems identified in 14CFR 43 appendix A could be interpreted to mean the Type Certificated design (the design submitted and approved in the sealed drawing package for the TC which hopefully is represented in the parts catalog for the given model. In the case of the cowling, anything that changes airflow could be considered a change in the basic design of the cooling system. Temper that with the definition in 1.1 for 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.
Changing the airflow changes cooling which could affect Powerplant operation. My vote is for major alteration.
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frequent_flyer
Registered User
Arizona, USA
I though the applicable term for that was "type design" (ref 14 CFR 21.31). If FAA intended "type design" why would they specify "basic design"?
Type design refers to the entire design of the TCd item (aircraft, engine, prop). Basic design in my opinion (for what it’s worth) would apply to only a portion of the TCd design (individual system) or components that aren’t TCd (TSO items). Again, just opinion.
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bob turner
Registered User
Interesting discussion. Lately out here one cannot purchase from manufacturers unless the part has a PMA or TSO.
My impression of 21.9 is that if a person "authorized" by the administrator approves a part, it need not have a PMA/TSO. Our local ACO does not see it that way - although that is the way it reads.
As to the GPS receptacle, it falls under PED guidance, which is fairly liberal. It can be permanent, hooked in to ship's power' and logbook entry.
Did you know that transponders are explicitly by regulation not required to be TSO?
My impression of 21.9 is that if a person "authorized" by the administrator approves a part, it need not have a PMA/TSO. Our local ACO does not see it that way - although that is the way it reads.
As to the GPS receptacle, it falls under PED guidance, which is fairly liberal. It can be permanent, hooked in to ship's power' and logbook entry.
Did you know that transponders are explicitly by regulation not required to be TSO?
And neither are ADSB out transmitters but try installing a non TSO unit on a certified airplane!
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bob turner
Registered User
Yeah - they are sure it is not allowed, but they cannot find a regulation. Jim Weir, of RST, used to go through this. As I understand it, they would make a special trip up to his place in the Sierras (they seem to travel in threes) but when he asked for chapter and verse they went away and never came back.
frequent_flyer
Registered User
Arizona, USA
I thought RST had gone out of business long before the introduction of ADS-B. I built three of the RST Xtal controlled aircraft band transceivers and still have one of them in my "museum".
skywagon8a
MEMBER
SE Mass MA6
This? http://rstengineering.com
I have one of their altitude encoders if anyone wants one. It was working fine when removed.
Steve Pierce
BENEFACTOR
Graham, TX
I have sat across the table from a Justice Department attorney with the FAA by her side who grilled me for almost 8 hours. There are things they can allege and the things they can hang you with, some are just scare tactics. Not much fun. I just try to stay out of those rooms.
