Installation of an Avionics Master Switch - Major or Minor?

[bnt83]

I see no connection between repair data and Certification requirements of new product. FAR 21&23. The forms you mentioned are used by DAR and FSDO to insure the data you are requesting to use is the proper method to do the repair.

Then you lack a fundemental understanding how airplanes and major repair and major alterations are approved. I'm not saying I know and understand it all because I don't.

But I do know that a Cesna 525C with a .5 inch painted band around the opening of an emergency exit would be unairworthy because the airplane was certified to part 23 Amemndements 23-1 through 23-57 (with a pile of extra stuff we won't get into).

The regulation the airplane must conform to is here (right from the TCDS and FARS):

Sec. 23.811

Emergency exit marking.

(a) Each emergency exit and external door in the passenger compartment must be externally marked and readily identifiable from outside the airplane by--
(1) A conspicuous visual identification scheme; and
(2) A permanent decal or placard on or adjacent to the emergency exit which shows the means of opening the emergency exit, including any special instructions, if applicable.
(b) In addition, for commuter category airplanes, these exits and doors must be internally marked with the word "exit" by a sign which has white letters 1 inch high on a red background 2 inches high, be self-illuminated or independently, internally-electrically illuminated, and have a minimum brightness of at least 160 microlamberts. The color may be reversed if the passenger compartment illumination is essentially the same.
[(c) In addition, when certification to the emergency exit provisions of Sec. 23.807(d)(4) is requested, the following apply:
(1) Each emergency exit, its means of access, and its means of opening, must be conspicuously marked;
(2) The identity and location of each emergency exit must be recognizable from a distance equal to the width of the cabin;
(3) Means must be provided to assist occupants in locating the emergency exits in conditions of dense smoke;
(4) The location of the operating handle and instructions for opening each emergency exit from inside the airplane must be shown by marking that is readable from a distance of 30 inches;
(5) Each passenger entry door operating handle must--
(i) Be self-illuminated with an initial brightness of at least 160 microlamberts; or
(ii) Be conspicuously located and well illuminated by the emergency lighting even in conditions of occupant crowding at the door;
(6) Each passenger entry door with a locking mechanism that is released by rotary motion of the handle must be marked--
(i) With a red arrow, with a shaft of at least three-fourths of an inch wide and a head twice the width of the shaft, extending along at least 70 degrees of arc at a radius approximately equal to three-fourths of the handle length;
(ii) So that the center line of the exit handle is within ± one inch of the projected point of the arrow when the handle has reached full travel and has released the locking mechanism; and
(iii) With the word "open" in red letters, one inch high, placed horizontally near the head of the arrow; and
(7) In addition to the requirements of paragraph (a) of this section, the external marking of each emergency exit must--
(i) Include a 2-inch colorband outlining the exit; and
(ii) Have a color contrast that is readily distinguishable from the surrounding fuselage surface. The contrast must be such that if the reflectance of the darker color is 15 percent or less, the reflectance of the lighter color must be at least 45 percent. "Reflectance" is the ratio of the luminous flux reflected by a body to the luminous flux it receives. When the reflectance of the darker color is greater than 15 percent, at least a 30 percent difference between its reflectance and the reflectance of the lighter color must be provided.]

Amdt. 23-46, Eff. 06/16/94

If repaint the airplane and this single aspect doesn't conform, the airplane is unairworthy.

Say this airplane was foreign registered and that county's TCDS showed that the airplane was certified in that country with a smoke detector in the baggage compartment and the airplane was imported to the USA and the FAA TCDS doesn't require that smoke detector, we can take it out. If we were exporting the airplane, a smoke detector must be installed.

 

[Tom-D]

Then you lack a fundemental understanding how airplanes and major repair and major alterations are approved. I'm not saying I know and understand it all because I don't.

But I do know that a Cesna 525C with a .5 inch painted band around the opening of an emergency exit would be unairworthy because the airplane was certified to part 23 Amemndements 23-1 through 23-57 (with a pile of extra stuff we won't get into).

The regulation the airplane must conform to is here (right from the TCDS and FARS):

Sec. 23.811

Emergency exit marking.

(a) Each emergency exit and external door in the passenger compartment must be externally marked and readily identifiable from outside the airplane by--
(1) A conspicuous visual identification scheme; and
(2) A permanent decal or placard on or adjacent to the emergency exit which shows the means of opening the emergency exit, including any special instructions, if applicable.
(b) In addition, for commuter category airplanes, these exits and doors must be internally marked with the word "exit" by a sign which has white letters 1 inch high on a red background 2 inches high, be self-illuminated or independently, internally-electrically illuminated, and have a minimum brightness of at least 160 microlamberts. The color may be reversed if the passenger compartment illumination is essentially the same.
[(c) In addition, when certification to the emergency exit provisions of Sec. 23.807(d)(4) is requested, the following apply:
(1) Each emergency exit, its means of access, and its means of opening, must be conspicuously marked;
(2) The identity and location of each emergency exit must be recognizable from a distance equal to the width of the cabin;
(3) Means must be provided to assist occupants in locating the emergency exits in conditions of dense smoke;
(4) The location of the operating handle and instructions for opening each emergency exit from inside the airplane must be shown by marking that is readable from a distance of 30 inches;
(5) Each passenger entry door operating handle must--
(i) Be self-illuminated with an initial brightness of at least 160 microlamberts; or
(ii) Be conspicuously located and well illuminated by the emergency lighting even in conditions of occupant crowding at the door;
(6) Each passenger entry door with a locking mechanism that is released by rotary motion of the handle must be marked--
(i) With a red arrow, with a shaft of at least three-fourths of an inch wide and a head twice the width of the shaft, extending along at least 70 degrees of arc at a radius approximately equal to three-fourths of the handle length;
(ii) So that the center line of the exit handle is within ± one inch of the projected point of the arrow when the handle has reached full travel and has released the locking mechanism; and
(iii) With the word "open" in red letters, one inch high, placed horizontally near the head of the arrow; and
(7) In addition to the requirements of paragraph (a) of this section, the external marking of each emergency exit must--
(i) Include a 2-inch colorband outlining the exit; and
(ii) Have a color contrast that is readily distinguishable from the surrounding fuselage surface. The contrast must be such that if the reflectance of the darker color is 15 percent or less, the reflectance of the lighter color must be at least 45 percent. "Reflectance" is the ratio of the luminous flux reflected by a body to the luminous flux it receives. When the reflectance of the darker color is greater than 15 percent, at least a 30 percent difference between its reflectance and the reflectance of the lighter color must be provided.]

Amdt. 23-46, Eff. 06/16/94

If repaint the airplane and this single aspect doesn't conform, the airplane is unairworthy.

Say this airplane was foreign registered and that county's TCDS showed that the airplane was certified in that country with a smoke detector in the baggage compartment and the airplane was imported to the USA and the FAA TCDS doesn't require that smoke detector, we can take it out. If we were exporting the airplane, a smoke detector must be installed.

When you make a response like this tells me you do not know how to comply with AC 210.
When you make a request for field approval, your request will fail the approval if the proper data is not used. For example, When your statement says "this repair will be refinished IAW Cessna's Original paint scheme" When that data is approved, the IA returning the repair to service best see a red stripe.

When your block 8 statement does not state how it is to be refinished, the field approval probably won't get approved, but if the FSDO does approve it, your stripe is no longer required.
the approval on a 337 (stamp in block 3 with signature) and a return to service by a IA, with make this a properly altered aircraft.

I say again, FAR 21 & 23 do not apply to altering aircraft. Simply because you are altering the certification requirements, the aircraft will no longer be as manufactured.

 

[kontiki]

Certification FARs certainly are what's applicable when obtaining approval for major alteration of aircraft. Different designees have different approval authorities, be it a DER, DAR, ODAR, I don't pretend to know the limits of the various roles. I don't know the limits of a Maintenance Inspector approval authority at a FSDO, but I'm pretty sure they can't approve anything that alters a certification requirement. I would expect it to go right up to the FAA Aircraft Certification Office.

The company I work for regularly obtains STCs when it makes sense to do so. Typically our DERs will assemble the data package and reports showing compliance with all of the affected certification requirements and other regulatory data if applicable. I've read more than a few of them, If tests are required, they have to be approved. It takes FAA approval to get the go ahead for initial installation and testing . Test data is then forwarded to ACO and usually we deactivate to get the ship back in service. FAA approves the change usually within about 90 days. There are no doubt other permutations.

Boeing has it's own sets of rules they have some sort of Organizational Designated Approval system. They apparently have less authority than the FAA but as TC holder and some kind of manufacturing authority have more approval authority than any of the designated authorities. They certainly do look back to the US cert requirements and a global based super set of operational requirements for Major Alterations too.

I've run a couple projects where we obtained STC approval for our installations using a DAS. The Designated Alteration Station can actually approve the STC for the FAA, however they will work very closely with their local ACO. Again, their people must be satisfied all the applicable certification standards that are impacted by a mod are met. The nice thing about a DAS is, if the testing goes well they can issue the STC the same day and you can start flying the modified aircraft right away. Of my two DAS projects, one time the tests went well and we got the STC the same day, one time it didn't and it got really ugly. Never hire a DAS that's in a long running feud with the OEM of an LRU you are trying to get an STC to install.

I'm not an IA so I cant really speak to the role of IA. I suspect it's an inspection role not all that different than an airline inspection role. I wouldn't expect the IA to ever be in the role of approving a configuration change that could affect a certification requirement.

Again, if you work for an airline that has money for engineering in house, these things go on all the time. My knowledge of everyone's role and process is incomplete, but I am sure of one thing. It's primarily about meeting the certification requirements or making sure they are unchanged. Safety does play a role, things cannot burst into flames either.

Our in house DERs can approve data on 8110 to support a major mod, but can't approve a major mod, they only recommend approval. Our in house DERs can approve some major repairs, again there is probably a very logical reason behind the difference.

Because we can make minor alterations to aircraft we operate, we frequently make minor alterations to wiring during STC installations. There have been times when the holder of the STC we bought rights to went into the high drama mode, because the STC holder had to get FAA approval for all changes to their STC major and minor. They accused us of doing things that were illegal. That's because they were a certified parts manufacturer, and had no authority or experience with minor change to wiring on an aircraft and we did. They couldn't change their STC because it's approved by the FAA.

I believe nobody changes anything specifically approved by the FAA but the FAA. That's just the pattern I observe, I haven't read it anywhere. This is not smokescreen or clouding the issue.

Personally I'm somewhat interested in setting up shop as a DER because I suspect GA needs a little help. I was burned out as an A&P long ago. The only reason I'm working on my airplane now is because I'm really tired of being told that I got stupider when got my Electrical Engineering degree by some chowder head that has yet to accomplish any work for me 100% right the first time, on my airplane.

Even the IA at the next closest field seemed to want to use the last admonition he got from the FSDO as a guide for adding things to a 337 for an STC when the things he wanted to add were already covered in the STC. He really had to be convinced!

Fortunately there is a new guy in our the office: A&P, IA CFI, retired radar engineer or something. I plan to use him for all 337 work in the future, I just don't see him, he's on different days and a different shift, and I don't like to bug him for small stuff.

 

[bnt83]

I say again, FAR 21 & 23 do not apply to altering aircraft. Simply because you are altering the certification requirements, the aircraft will no longer be as manufactured.

That's just it Tom, 95% of the time they are NOT changing the cert basis of the aircraft. The data created to perform major alterations and major repairs is to MEET the ORIGINAL cert basis of the aircraft.

The TCDS cert basis is the minimum standards the airplane must MEET. Major repairs must meet that same minimum standard. Major alterations must meet that minimum standard.

Example. We have an airplane with Dave's Seats in the cabin. Dave's Seats sells seats to anyone and has no idea what make/models or floorplans they went into. Dave's Seats issues a service bulletin for their seats to increase the travel limits of the seat base and the backrest with new stops. There is no specific airplane make/model information in the bulletin. If you blindly install them you'll likely render the airplane unairworthy as the seats could easily intrude on the minimum isle widths and the emergence exit protected area, found in the airplanes certification basis on the TCDS.

These are generalizations and its very case by case, but this is a huge slice of it.

 

[Tom-D]

That's just it Tom, 95% of the time they are NOT changing the cert basis of the aircraft. The data created to perform major alterations and major repairs is to MEET the ORIGINAL cert basis of the aircraft.

Then you are doing a major repair, not a major alteration. And completed with a whole different set of data, and usually from the manufacturers manuals.

The TCDS cert basis is the minimum standards the airplane must MEET. Major repairs must meet that same minimum standard. Major alterations must meet that minimum standard.

This is true, but not the issue at hand in the OP's first question.

Example. We have an airplane with Dave's Seats in the cabin. Dave's Seats sells seats to anyone and has no idea what make/models or floorplans they went into. Dave's Seats issues a service bulletin for their seats to increase the travel limits of the seat base and the backrest with new stops. There is no specific airplane make/model information in the bulletin. If you blindly install them you'll likely render the airplane unairworthy as the seats could easily intrude on the minimum isle widths and the emergence exit protected area, found in the airplanes certification basis on the TCDS.

These are generalizations and its very case by case, but this is a huge slice of it.

and a whole different issue to this thread. But you can still gain the proper paper, using the field approval system. When the aircraft has been properly altered it no longer is required to meet FAR 21 & 23.

 

[bnt83]

I see no connection between repair data and Certification requirements of new product. FAR 21&23. The forms you mentioned are used by DAR and FSDO to insure the data you are requesting to use is the proper method to do the repair.

and a whole different issue to this thread. But you can still gain the proper paper, using the field approval system. When the aircraft has been properly altered it no longer is required to meet FAR 21 & 23.

Sorry Tom, I disagree.

http://www.faa.gov/documentLibrary/media/Order/8300_16.pdf

Major Repair and Alteration Data Approval

 

[Tom-D]

Sorry Tom, I disagree.

http://www.faa.gov/documentLibrary/media/Order/8300_16.pdf

Major Repair and Alteration Data Approval

Do you know the difference between the data gathered and the data approved? and who does what?

This 8300.16 is used by FSDO to insure you use the proper information and refer to the proper data to be approved for the alterations.

This why I referred to the 43-13 you must quote proper page and paragraph, or provide engineering to be tested and approved prior to returning to standard airworthiness.

 

[bnt83]

Do you know the difference between the data gathered and the data approved? and who does what?

This 8300.16 is used by FSDO to insure you use the proper information and refer to the proper data to be approved for the alterations.

This why I referred to the 43-13 you must quote proper page and paragraph, or provide engineering to be tested and approved prior to returning to standard airworthiness.

Now you are redirecting. You have said multiple times in this thread that there is no connection between CAR 3, Part 21, Part 23 and approval of major alteration and major repair data, I just showed you there is.

 

[Tom-D]

Now you are redirecting. You have said multiple times in this thread that there is no connection between CAR 3, Part 21, Part 23 and approval of major alteration and major repair data, I just showed you there is.

How can you comply with certification requirements when you are modifying the aircraft? This is the thinking of way too many who work at FSDO and reason we are getting FAR 23 re-written. simply because you can't.
Why do we use DARs & DERs If we must comply with Certification requirements that would require us to replace any part with new each time we repaired any portion of the aircraft, If we could not deviate from certification requirements Why do we have rules like "major and Minor"

Rules for repair, and modification are not in 21 & 23 for a reason.

 

[bnt83]

How can you comply with certification requirements when you are modifying the aircraft?

Here is an easy example. This STC certificate says that the STC data has shown compliance with,

23.1 applicability
23.25(a) weight limits (which makes no sense to me at all why they put that on there)
23.867(a)(b) Electrical Bonding and protection against lightening and static discharge
23.1301 Function and Installation
23.1309(a)(c) Equipment, systems and installations
23.1351(a) Electrical systems and equipment general
23.1357(a)(b)(c) Circuit Protective Devices
23.1365(a) Cables and equipment
23.1367(a) Switches
23.1383 Taxi and Landing Lights
23.1397(c) Color Specifications
23.1529 Instructions for Continued Airworthiness



Now that they have data showing compliance with all those regulations they can compare like aircraft with similar TCDS certification basis and list all those aircraft on an Approved Model List, without having to actually install the STC on them (about 30 pages of makes & models).

http://www.whelen.com/pb/Aviation/STC/STC SA00344BO.pdf

 

[Tom-D]

Here is an easy example. This STC certificate says that the STC data has shown compliance with,

23.1 applicability
23.25(a) weight limits (which makes no sense to me at all why they put that on there)
23.867(a)(b) Electrical Bonding and protection against lightening and static discharge
23.1301 Function and Installation
23.1309(a)(c) Equipment, systems and installations
23.1351(a) Electrical systems and equipment general
23.1357(a)(b)(c) Circuit Protective Devices
23.1365(a) Cables and equipment
23.1367(a) Switches
23.1383 Taxi and Landing Lights
23.1397(c) Color Specifications
23.1529 Instructions for Continued Airworthiness



Now that they have data showing compliance with all those regulations they can compare like aircraft with similar TCDS certification basis and list all those aircraft on an Approved Model List, without having to actually install the STC on them (about 30 pages of makes & models).

http://www.whelen.com/pb/Aviation/STC/STC SA00344BO.pdf

What does Installation of a STC have to with gaining approval of a modification by field approval? FAR 23 or 21 do not give you the data or the process to do this.
You the originator of the 337 to be approved by FSDO must provide the proper engineering or data to make the modification.
All the forms you have provided only say the FSDO must do is insure the data or the engineering is correct. prior to approval

 

[Tom-D]

Do you realize that all the engineering for a STC has all ready been thru the testing process prior to the FAA approving it to be installed as a modification to the aircraft with out further approval by the FAA. And that process has nothing to do with FAR 21 or 23

 

[Tom-D]

You need to read and understand 21.111- 21.115

It's the how to. not the engineering.

Field approval process, it's not there.

 

[Tom-D]

FAR 23, it's the standard of minimum airworthiness, not the engineering to gain the standard. It doesn't tell us how to do that.

 

[kontiki]

Came across this the other day when looking at circuit breaker switches.

http://www.csobeech.com/breaker-switches.html

Thanks for the heads up on this. The switch they used for the avionics master was a W31-X2M1G-35. I know from the sellers photos, it was installed between Feb and Aug 2013. There had been a second one in the airplane too. It was another one of those suspicious kludges, I believe to supply power to one of those ice chest air conditioners. I had already pulled it, it was a W31-X2M1G-15. I tossed them both tonight.

 

[bnt83]

Field approval process, it's not there.

I get that but your application for a field approval is really treated the same as an STC (in theory) when you show on a 337 that you used, for example appropriate wiring and busing techniques found in 43.13, (assuming other things are also good enough) you have substantiation enough that an ASI can use that FAA order (above) to stamp your field approval in block 3 "I find the data listed herein complies with applicable airworthiness standards..."

If we know what our work (data on the 337) is going to be graded to (airworthiness standards) we should be able to get the field approval much easier.

If we are dinking with the nav lights or strobes, we should be looking at the those regulations before we even start.

 

[kontiki]

I get that but your application for a field approval is really treated the same as an STC (in theory)

I wondered about that. The FAA description of the process makes me think the FSDO has options that could preclude review by the ACO. This is a process I have no first hand experience with. I do know of some really good techs that had no luck making it work without DER review of the data.

I doubt the same application for a field approval by an individual A&P is looked at the same way as one from a Part 145 applicant too. Again, different set of privileges under the FARs.

I believe the FAA probably has no spare resources to handle engineering review work for applicants.

See -> https://www.faa.gov/aircraft/air_cert/design_approvals/field_approvals/field_approv_proc/

 

[bnt83]

I wondered about that. The FAA description of the process makes me think the FSDO has options that could preclude review by the ACO. This is a process I have no first hand experience with. I do know of some really good techs that had no luck making it work without DER review of the data.

I believe the FAA probably has no spare resources to handle engineering review work for the applicant.

See -> https://www.faa.gov/aircraft/air_cert/design_approvals/field_approvals/field_approv_proc/

What I find curious is that there are STCs out there that don't cover all data needed. There should be warning about that in the installation instructions somewhere but how are you supposed to know prior to buying it?

Say for example you buy red and green TSOed nav light assemblies that are on an STC. That STC certificate will most likely not show compliance with 23.1385 (position lights installation) because they don't know what the white light on the tail is and 23.1385 covers the whole system including patterns, intensities, angles and so on. Since you are mixing a new red and green with an existing white, it may not really be approved in a paper trail.

The TSO in this case only approved the color of the lights, and not light pattern or intensities.

Kind of a goofy deal.

 

[kontiki]

What I find curious is that there are STCs out there that don't cover all data needed. There should be warning about that in the installation instructions somewhere but how are you supposed to know prior to buying it?

Say for example you buy red and green TSOed nav light assemblies that are on an STC. That STC certificate will most likely not show compliance with 23.1385 (position lights installation) because they don't know what the white light on the tail is and 23.1385 covers the whole system including patterns, intensities, angles and so on. Since you are mixing a new red and green with an existing white, it may not really be approved in a paper trail.

The TSO in this case only approved the color of the lights, and not light pattern or intensities.

Kind of a goofy deal.

I don't think someone that gets the right to use the STC will get the Master Data List /Master DWG List containing all the approval docs submitted to the FAA. That is really intellectual property (IP).

For the most part all an installer needs is installation data: STC, docs showing applicability, ICAW, changes to POH or operating data, parts or parts lists (maybe PMA depending on type of parts) and permission letter.

For example, if STC installation requires standard parts, connectors, pins wire etc, no issue they provide a BOM. If they define a prefabricated harness on a company DWG, probably a PMA involved to ensure P/N identified on DWG is assembled to standards (because it's not necessarily done by an A&P).

I'm sure there are lots of other permutations, I'm more familiar with avionics.

 

[bnt83]

QUOTE="kontiki, post: 2045351, member: 9475"]I don't think someone that gets the right to use the STC will get the Master Data List /Master DWG List containing all the approval docs submitted to the FAA. That is really intellectual property (IP).

For the most part all an installer needs is installation data: STC, docs showing applicability, ICAW, changes to POH or operating data, parts or parts lists (maybe PMA depending on type of parts) and permission letter.

For example, if STC installation requires standard parts, connectors, pins wire etc, no issue they provide a BOM. If they define a prefabricated harness on a company DWG, probably a PMA involved to ensure P/N identified on DWG is assembled to standards (because it's not necessarily done by an A&P).

I'm sure there are lots of other permutations, I'm more familiar with avionics.[/QUOTE]

From my experience the installer gets the MDL. I've even caught installation drawings, ICAs AFMSs with a revision level that were not approved on the MDL rev the STC holder provided. That's always fun.

You mentioned missing LOAs a while back and in my experience some of them contain language that says they are not to be released to anyone other than the installer. I don't like it but...

The point was, if we dink with the LH&RH wing nav lights (only the red and green) using an STC and that STC certificate doesn't list 23.1385 (position lights system installation) is the whole system in compliance or not? The drawings do not specify which light must be on the tail (white one) or any other considerations of it. It would be up to the installer to determine or show compliance with 23.1385 (compliance of the system as a whole).

Similar things has ended up in ADs in the past. There was a combination of STCs installed on a like twin and an placarded airspeed was conflicting between the two STCs. It was an STC engine upgrade and a separate STC propeller upgrade (IRRC) that didn't mesh well.

 

[GlennAB1]

Then you lack a fundemental understanding how airplanes and major repair and major alterations are approved. I'm not saying I know and understand it all because I don't.
But I do know that a Cesna 525C with a .5 inch painted band around the opening of an emergency exit would be unairworthy because the airplane was certified to part 23 Amemndements 23-1 through 23-57 (with a pile of extra stuff we won't get into).
The regulation the airplane must conform to is here (right from the TCDS and FARS):
Sec. 23.811
Emergency exit marking.
(a) Each emergency exit and external door in the passenger compartment must be externally marked and readily identifiable from outside the airplane by--;
(7) In addition to the requirements of paragraph (a) of this section, the external marking of each emergency exit must--
(i) Include a 2-inch colorband outlining the exit; and
(ii) Have a color contrast that is readily distinguishable from the surrounding fuselage surface. The contrast must be such that if the reflectance of the darker color is 15 percent or less, the reflectance of the lighter color must be at least 45 percent. "Reflectance" is the ratio of the luminous flux reflected by a body to the luminous flux it receives. When the reflectance of the darker color is greater than 15 percent, at least a 30 percent difference between its reflectance and the reflectance of the lighter color must be provided.]
If repaint the airplane and this single aspect doesn't conform, the airplane is unairworthy.

Just for S&G's; Is the 2" colorband required to be on the opening or may it be on the exit itself? Could it be .5" on the opening and 1.5" on the exit?

 

[kontiki]

QUOTE="kontiki, post: 2045351, member: 9475"]
The point was, if we dink with the LH&RH wing nav lights (only the red and green) using an STC and that STC certificate doesn't list 23.1385 (position lights system installation) is the whole system in compliance or not? The drawings do not specify which light must be on the tail (white one) or any other considerations of it. It would be up to the installer to determine or show compliance with 23.1385 (compliance of the system as a whole).

Similar things has ended up in ADs in the past. There was a combination of STCs installed on a like twin and an placarded airspeed was conflicting between the two STCs. It was an STC engine upgrade and a separate STC propeller upgrade (IRRC) that didn't mesh well.

You may get the MDL, but probably not all the data. Maybe I misspoke there. I wouldn't have any idea what the particulars are without reviewing everything and maybe then I wouldn't see a clean answer.

The devil is always in the details. Things frequently seem all over the map when you don't have all of the details that people handling it were aware of. That's frustrating if your company is looking at a regulatory deadline and you are excluded from the discussions with the FAA, because you farmed development out.

How was STC effectivity handled? If it's effectivity by aircraft model, whose job is it to address all the irregularities found from aircraft to aircraft? I've seen obvious mistakes too.

STC holder subbed development of their STC revision (new LRU P/N for them, our fleet) to an engineering company that approved data that was flat out wrong in a couple places. Folks in the hangar couldn't avoid seeing the problem, not obvious from the DWGs alone. No more money left in their budget under existing agreement for further work. That's when it really became our problem.

 

[bnt83]

Just for S&G's; Is the 2" colorband required to be on the opening or may it be on the exit itself? Could it be .5" on the opening and 1.5" on the exit?

LOL!

 

[GlennAB1]

Seriously! From a legal point of view, not aesthetics.

 

[Tom-D]

This thread is so far off topic It's useless to try to get the OP's question answered, like usual for this page.
I'll simply continuing to gain field approvals by submitting the data and engineering like usual, and get the job done.

 

[thomasdr72]

Adding the avionics master breaker is a minor alteration. However, the components used must be appropriately rated for the function that is intended to perform, otherwise all arguments are moot.

Instead of pulling it all out, just fix it.

Cheers!

Dana

 

[GlennAB1]

The alteration was never documented. You gonna fix something that technically doesn't exist (legally)? Some aircraft are certificated with power feeder protection or bus tie protection. This aircraft wasn't. It is an alteration to basic electrical system design, which constitutes it being a major.

 

[thomasdr72]

Of course I'm going to fix it, as long as the owner authorizes the work to be done. If not, it goes on the list of discrepancies given to the owner in this "date." And then the owner can get it fixed wherever they choose to do so.

However, by your definition, every time I add a circuit breaker and switch to control a new widget I am performing a major modification.

The basic design is this: 12v, negative ground, lead-acid storage battery, engine driven alternator. Everything else is minor changes, using common methods and practices. No matter if you believe the elections flow from positive to negative, or negative to positive, the basic schematic is the same. Just because there is one additional breaker that happens to interrupt the power to all radios is moot. By definition: if it isn't major --the only choice is minor. So many mechanics fill out 337's to document things that could be a logbook entry.

However: If the individual IA wishes to exercise the privileges of his certificate, and it is in their judgment that a 337 is necessary, draw it up and send it in. There is plenty of approved data and techniques in the book to fill out the form, and it only costs a little time and a stamp. I've never met an IA that ever got one back rejected. IMHO, the clerk that scans it into the permanent aircraft record is the only person who ever sees them. YMMV!

V/r,

Dana

 

[GlennAB1]

Is the aircraft altered from basic design shown in the POH, AFM, etc.?

 

[weirdjim]

The basic design is this: 12v, negative ground, lead-acid storage battery, engine driven alternator. Everything else is minor changes, using common methods and practices. No matter if you believe the elections flow from positive to negative, or negative to positive, the basic schematic is the same. Just because there is one additional breaker that happens to interrupt the power to all radios is moot. By definition: if it isn't major --the only choice is minor. So many mechanics fill out 337's to document things that could be a logbook entry.

However: If the individual IA wishes to exercise the privileges of his certificate, and it is in their judgment that a 337 is necessary, draw it up and send it in. There is plenty of approved data and techniques in the book to fill out the form, and it only costs a little time and a stamp. I've never met an IA that ever got one back rejected. IMHO, the clerk that scans it into the permanent aircraft record is the only person who ever sees them. YMMV!

V/r,

Dana

Amen. At last somebody with a touch of practical sanity in this group.

Jim

 

[Ravioli]

Looks like putting in a worthless Avionics Master Switch might be a minor alteration, but it's a MAJOR bone of contention.

I'm back to my original opinion: every manufacturer of my avionics says it's unneeded (Garmin, Dynon, Trutrak) so I just leave them on.

Lets get back to high wing / low wing or nose gear / tailwheel religious debates!

 

[thomasdr72]

Looks like putting in a worthless Avionics Master Switch might be a minor alteration, but it's a MAJOR bone of contention.

I'm back to my original opinion: every manufacturer of my avionics says it's unneeded (Garmin, Dynon, Trutrak) so I just leave them on.

Excellent idea, hopefully it never makes a bit of difference... I've heard claims of guys that had to repair $10k worth of radios because of voltage spikes during start. But I have no idea if there is any credence to any of those claims or not. All I know is that I personally wanted some cheap insurance to make sure I've never personally had to find out.

I do know, that for almost every radio stack I've installed, I usually made sure that there was a appropriately-rated single switch-type aviation breaker that served as the avionics master. I've never burned out a radio while it was disconnected from the bus during startup. It's not scientific, but it seems to make sense with my feeble ex aircraft electrician's brain.

V/r,

-Dana

 

[weirdjim]

Excellent idea, hopefully it never makes a bit of difference... I've heard claims of guys that had to repair $10k worth of radios because of voltage spikes during start. But I have no idea if there is any credence to any of those claims or not. All I know is that I personally wanted some cheap insurance to make sure I've never personally had to find out.
-Dana

Unfortunately, I have. The last series of radios that were somewhat inpenetrable to starter spikes were the venerable MK-12s, "radios that glowed in the dark" with vacuum tubes, for which a spike was the bite of a flea. Depending on what lets go when silicon french-fries it can be a single device or every damned transistor/IC in the box. Yes, I've had to pronounce the final rites on a few of them and their owners were NOT happy. NONE of them had radio master switches or breakers that could serve as switches.

As you, I've got an airplane that is 6 decades out of Wichita, and every one of them (including the venerable C-120 Heavy) had an electronics master switch. A VERY old IA that mentored me starting in 1963 beat it into my head that delicate electronics and heavy motor spikes don't belong on the same bus.

Nice to see you on the board.

Jim

 

[thomasdr72]

Is the aircraft altered from basic design shown in the POH, AFM, etc.?

During an annual inspection, the IA is responsible to make sure that the aircraft conforms to its original airworthy, or properly altered condition. They are a lot of ways that you get to this "properly altered" condition. Birds that have a very restrictive and detailed AFM/TCDS require more paperwork and study (and sometimes approvals) before you can get to this "properly altered" condition.

CAR3 birds, with the basic 45-page owners manual printed in the 50/60/70's are much different than a new Cirrus. As an IA, I start with the checklist in FAR43, then move to the TCDS. After those two references, it depends what kind of bird it is, and what other data is available. When I sign off an annual, it is in accordance with (IAW) FAR43, Appendix D. Pretty much everything else is a reference. (REF: Cessna 100-series service manual).

The bird must conform to the specifications in the TCDS. If it doesn't, it must be properly altered (enter the STC, or other data). That's normally where the digging stops.

Otherwise, we'd still be using Narco superhomers, and running our oil dilution systems. Those are in my owners manual...

V/r,

-Dana

 

[GlennAB1]

During an annual inspection, the IA is responsible to make sure that the aircraft conforms to its original airworthy, or properly altered condition. They are a lot of ways that you get to this "properly altered" condition. Birds that have a very restrictive and detailed AFM/TCDS require more paperwork and study (and sometimes approvals) before you can get to this "properly altered" condition.

CAR3 birds, with the basic 45-page owners manual printed in the 50/60/70's are much different than a new Cirrus. As an IA, I start with the checklist in FAR43, then move to the TCDS. After those two references, it depends what kind of bird it is, and what other data is available. When I sign off an annual, it is in accordance with (IAW) FAR43, Appendix D. Pretty much everything else is a reference. (REF: Cessna 100-series service manual).

The bird must conform to the specifications in the TCDS. If it doesn't, it must be properly altered (enter the STC, or other data). That's normally where the digging stops.

Otherwise, we'd still be using Narco superhomers, and running our oil dilution systems. Those are in my owners manual...

V/r,

-Dana

Radios and oil dilution aren't being debated as major alterations, I believe everyone would agree they would be minor. Changes to the basic design of the electrical system, which would be a major, is the argument. And I believe every aircraft I've worked on the electrical system basic description included the bus/busses.