AIRSPEED SAFETY SWITCH AVAILABILITY

[DCarlton]

I've noticed that several folks may need an airspeed safety switch and they've been waiting for some time to get a part from Mooney.  According to World Magnetics (they appear to have bought out VEP Products), VEP has made two airspeed switches for Mooney.  If the World Magnetics P/N or VEP P/N and specs can be mapped to the Mooney P/Ns, the switches are available new.  One runs $1398 and the other $1500.  There's a three week lead time.  I originally had a Dukes switch in my airplane and it was replaced with a VEP switch years ago.  Bottom line, if you need a switch, they appear to be physically available.  Someone with proper experience just needs to make sure the paper trail is appropriate for aircraft installation.  That's an area where I have no experience.  

I'm not a mechanic or a parts supplier.  Just a guy that's pulled the thread on airspeed switch availability with the OEM.  I had to troubleshoot mine this week during annual inspection.  

[carusoam]

Nice work DC!

Thanks for sharing the details…

Best regards,

-a-

[thinwing]

the switch in my bravo appears identical to VEP series 654 and is speced to .5 in to 6psig.It has a double output to ground or center wwire...that implys a DPST switch config.Are switchs are designed to activate about 70 I believe ...it is adjustable by a central screw compressing a spring to preload a diaphram.If I was desperate ,I would purchase a vep 654 stdp model and reuse the spring from my old switch....of course this wouldnt be a legal part..

[DCarlton]

Attached are the P/Ns and drawings for one of the VEP Air Speed Sensors (switches) previously manufactured for Mooney.  See the Item No (V21614) and Line 1, Line 2 and Line 40 of the -1 drawing.  The VEP Model No is 654-34.  Note the customer identification on Line 2 as Mooney.  This is the switch that was quoted to have a 3 week lead time for $1500.  

Contact Rob Livingston at World Magnets for more information, 231-922-7622 or email rlivingston@worldmagnetics.com

I have no idea if the necessary paperwork can be provided for installation.  Perhaps this drawing is enough.  I'm not a mechanic or parts supplier.  Just a Mooney flyer... 

V21614-1.pdf V21614-2.pdf

Edited August 7, 2021 by DCarlton

[EricJ]

24 minutes ago, DCarlton said:

Attached are the P/Ns and drawings for one of the VEP Air Speed Sensors (switches) previously manufactured for Mooney.  See the Item No (V21614) and Line 1, Line 2 and Line 40 of the -1 drawing.  The VEP Model No is 654-34.  Note the customer identification on Line 2 as Mooney.  This is the switch that was quoted to have a 3 week lead time for $1500.  

Contact Rob Livingston at World Magnets for more information, 231-922-7622 or email rlivingston@worldmagnetics.com

I have no idea if the necessary paperwork can be provided for installation.  Perhaps this drawing is enough.  I'm not a mechanic or parts supplier.  Just a Mooney flyer... 

V21614-1.pdf 303.15 kB · 0 downloads V21614-2.pdf 283.72 kB · 0 downloads

That's useful and would also allow somebody to test it to spec pretty easily, possibly to facilitate repair/adjustment rather than replacement.

[PT20J]

1 hour ago, DCarlton said:

Attached are the P/Ns and drawings for one of the VEP Air Speed Sensors (switches) previously manufactured for Mooney.  See the Item No (V21614) and Line 1, Line 2 and Line 40 of the -1 drawing.  The VEP Model No is 654-34.  Note the customer identification on Line 2 as Mooney.  This is the switch that was quoted to have a 3 week lead time for $1500.  

Contact Rob Livingston at World Magnets for more information, 231-922-7622 or email rlivingston@worldmagnetics.com

I have no idea if the necessary paperwork can be provided for installation.  Perhaps this drawing is enough.  I'm not a mechanic or parts supplier.  Just a Mooney flyer... 

V21614-1.pdf 303.15 kB · 2 downloads V21614-2.pdf 283.72 kB · 5 downloads

The Mooney part number listed on the drawing is 880013-505. There is a comment in the M20J IPC that says:

S/N 24-0001 - S/N 24-1685 order 880013-505 (All earlier 14V). S/N 24-1686 - S/N 24-TBA order 88013-507 (later 14V and ALL 28V).

Skip

[DCarlton]

11 minutes ago, PT20J said:

The Mooney part number listed on the drawing is 880013-505. There is a comment in the M20J IPC that says:

S/N 24-0001 - S/N 24-1685 order 880013-505 (All earlier 14V). S/N 24-1686 - S/N 24-TBA order 88013-507 (later 14V and ALL 28V).

Skip

Although I'm no expert, it seems like the OEM drawing and IPC you reference is enough to support installation if the part if purchased directly from World Magnetics.  Anybody with experience in this area agree?  

[PT20J]

1 hour ago, EricJ said:

That's useful and would also allow somebody to test it to spec pretty easily, possibly to facilitate repair/adjustment rather than replacement.

The VEP drawing lists component parts. I wonder if they would sell the diaphragm which is what I expect usually goes bad and then it might be possible to rebuild one. Not sure if this would be considered an "instrument" in the sense that it would need to be rebuilt by a repair station. 

If you have a Mooney IPC that lists a Mooney Part Number, and a Vendor drawing that lists the same part number, is there any reason that you can't install one purchased from the vendor rather than Mooney? Or, maybe you send the drawing back to the vendor and call it an OSP -- kind of like the suspension donuts?

Skip

[DCarlton]

5 hours ago, PT20J said:

The VEP drawing lists component parts. I wonder if they would sell the diaphragm which is what I expect usually goes bad and then it might be possible to rebuild one. Not sure if this would be considered an "instrument" in the sense that it would need to be rebuilt by a repair station. 

If you have a Mooney IPC that lists a Mooney Part Number, and a Vendor drawing that lists the same part number, is there any reason that you can't install one purchased from the vendor rather than Mooney? Or, maybe you send the drawing back to the vendor and call it an OSP -- kind of like the suspension donuts?

Skip

I could ask the vendor if they would support overhauls of these devices but I'm not optimistic.  But like you said, the question then becomes whether they are certified to rebuild one or whether it could be done in the field.  Although they are very expensive, seeing them still in production is reassuring.  

Edited August 8, 2021 by DCarlton

[EricJ]

14 hours ago, DCarlton said:

I could ask the vendor if they would support overhauls of these devices but I'm not optimistic.  But like you said, the question then becomes whether they are certified to rebuild one or whether it could be done in the field.  Although they are very expensive, seeing them still in production is reassuring.  

If you call them, ask if they'll sell parts.

 

[Cyril Gibb]

On 8/6/2021 at 3:11 PM, thinwing said:

the switch in my bravo appears identical to VEP series 654 and is speced to .5 in to 6psig.It has a double output to ground or center wwire...that implys a DPST switch config.Are switchs are designed to activate about 70 I believe ...it is adjustable by a central screw compressing a spring to preload a diaphram.If I was desperate ,I would purchase a vep 654 stdp model and reuse the spring from my old switch....of course this wouldnt be a legal part..

If you have a faulty or intermittent switch, test the other 3-wire bundle to see if it works correctly.

The unit actually has two SPST microswitches inside, each with NO and NC connections.  The NC is for the Sonalert and the NO for gear operation.   If you swap the the connector wires to use the typically unused switch (for Hobbs Meters?) it will save you some $$.

In the connector, swap red->green  blue->yellow  white-> black   (reverse the colours)

[thinwing]

3 hours ago, Cyril Gibb said:

If you have a faulty or intermittent switch, test the other 3-wire bundle to see if it works correctly.

The unit actually has two SPST microswitches inside, each with NO and NC connections.  The NC is for the Sonalert and the NO for gear operation.   If you swap the the connector wires to use the typically unused switch (for Hobbs Meters?) it will save you some $$.

In the connector, swap red->green  blue->yellow  white-> black   (reverse the colours)

interesting...on my bravo..only 1 ground to device was in use (airspeed gear safety)so we used the other output  as  ground to air sensor for adsb transpd. status input.

[A64Pilot]

On 8/7/2021 at 3:55 PM, PT20J said:

The VEP drawing lists component parts. I wonder if they would sell the diaphragm which is what I expect usually goes bad and then it might be possible to rebuild one. Not sure if this would be considered an "instrument" in the sense that it would need to be rebuilt by a repair station. 

If you have a Mooney IPC that lists a Mooney Part Number, and a Vendor drawing that lists the same part number, is there any reason that you can't install one purchased from the vendor rather than Mooney? Or, maybe you send the drawing back to the vendor and call it an OSP -- kind of like the suspension donuts?

Skip

As it doesn’t drive any kind of display, in my opinion it’s not an instrument.

Again another opinion but I don't see replacing this diaphragm as any different from any other.

An A&P I believe is allowed to adjust this device I believe, it doesn’t have to go to an instrument repair station, further enforcing it’s not an instrument. 

At least that would be my argument, I doubt any FAA inspector would fault me.

[A64Pilot]

On 8/7/2021 at 3:55 PM, PT20J said:

If you have a Mooney IPC that lists a Mooney Part Number, and a Vendor drawing that lists the same part number, is there any reason that you can't install one purchased from the vendor rather than Mooney? Or, maybe you send the drawing back to the vendor and call it an OSP -- kind of like the suspension donuts?

Skip

You can’t use a part supplied directly from a vendor unless that vendor has a PMA, It’s the induction into Mooney’s QC system that makes it an aircraft part, adds traceability etc.

However if in your opinion that part is a “standard” part and if it conforms to pretty much any kind of standard, then you can. Pretty much everything is made to some kind of standard.

All M20’s even the last ones built are covered by this AC https://www.faa.gov/documentLibrary/media/Advisory_Circular/AC_23-27.pdf

In my opinion I think I’d determine it’s a standard part

The landing gear donuts won’t in my opinion stand up as an owner produced part as the owner really didn’t participate in the production of the part, if someone actually contacted a manufacturer and supplied dimensions, materials list and durometer etc, then that’s an actual OPP, but signing some kind of document that’s pre prepared and having something that was manufactured before you contacted them is going to be tough to defend if you ever had to.

If we are talking about the ones I think we are.

Simply sending someone a drawing for a part they already manufacture, isn’t participating in the manufacture of that part.

 

Edited April 17, 2022 by A64Pilot

[Andy95W]

33 minutes ago, A64Pilot said:

 

Simply sending someone a drawing for a part they already manufacture, isn’t participating in the manufacture of that part.

 

This statement is inaccurate.  It may apply to products like shock discs, but not necessarily other items.

Providing a drawing to McFarlane to produce a prop or throttle cable is precisely how its been done for years to call it an owner-provided part, and the FAA has never had an issue with it.

[A64Pilot]

2 hours ago, Andy95W said:

This statement is inaccurate.  It may apply to products like shock discs, but not necessarily other items.

Providing a drawing to McFarlane to produce a prop or throttle cable is precisely how its been done for years to call it an owner-provided part, and the FAA has never had an issue with it.

What you said is correct, if they produce the cable from your drawing, you participated in the manufacture of the part.

But if you send them a drawing for a product they already produce and they send it to you doesn’t make it an OPP, and the FAA chooses sometimes to not enforce every thing, cause I suspect by now Mcfarlane knows what a Mooney throttle cable look like.

If you send them your old cable and said build a copy of this, even that’s usually considered to be an OPP.

FAA has operated pretty loose from a legality stand point for a long time, AC’s and memorandums are not laws or regulations, those are called FAR’s but as they are judge, jury and executioner I guess they can pretty much do as they please.

But and here is the thing, if you produce an OPP you have to ensure it conforms to type design, things like heat treat level and material etc, not just that it physically matches the dimensions of the original part. So what’s the durometer of a Mooney landing gear shock biscuit? I don’t know either, but that’s about the most important part of an elastomer used for shock absorption you need to produce one.

Your example of the Mcfarlane control cable, the FAA isn’t always stupid, they have enough sense to know that’s about your best source for a safe and airworthy part, most inspectors won’t trip over an interpretation of intent. Most don’t want you trying to modify a lawnmower cable or something, they had rather you use the Mcfarlane part than you trying to roll your own

Exhaust systems that are “repaired” not manufactured are treated the same, what you get back is very often 100% new, not repaired. The same with baffles. But to cover the “repairer” they require you to send them something so they can claim to have repaired it.

This discussion started with the theory that you could send a Mooney drawing to the vendor who made the part, and they send you an already manufactured part that matches the Mooney drawing, is that an OPP? The answer is no, because you didn’t participate in the manufacture of the part, the part is an already existing off the shelf part.

So my answer to be able to use the part is to consider it a “standard part” and then you can.

It also in my opinion looks better in the logbook that you replaced x part with a commercially available standard part IAW with AC 23-27, than I owner put home made parts in, but that’s my opinion.

I put standard parts in every now and again, last ones were landing gear relays, there are 0 available for my Mooney under Mooney part number but as they are actually widely available commercial standard parts with known specs it’s easy. Same with my landing gear switch, 0 available, but the switch has an MS number which makes it a standard part, just swap the plastic wheel over, I don’t know the source for that, I assume Mooney had them injection molded.

I’m sure the limit switches are the same, unfortunately I don’t have their MS or equalivent part number, but if anyone does I’d appreciate the numbers, but I suspect different switches were used over the years, like the relays were.

Edited April 17, 2022 by A64Pilot

[EricJ]

3 hours ago, Andy95W said:

This statement is inaccurate.  It may apply to products like shock discs, but not necessarily other items.

Providing a drawing to McFarlane to produce a prop or throttle cable is precisely how its been done for years to call it an owner-provided part, and the FAA has never had an issue with it.

Yes, there's nothing stopping a supplier from using an off-the-shelf part to meet your drawing or spec, and they may not even inform you if they do.   There's nothing in the regs that prevents this for OPP.

I ordered two control cables from McFarlane using OPP, and when I got them there'd be no way to know if they hadn't just pulled the Mooney drawing and built to it, or checked against it, or whatever, as I provided the part number that went with it.

I ordered a third control cable from McFarlane using the Mooney part number.   The OPP parts fit better, so maybe there is a distinction. 

 

[A64Pilot]

49 minutes ago, EricJ said:

Yes, there's nothing stopping a supplier from using an off-the-shelf part to meet your drawing or spec, and they may not even inform you if they do.   There's nothing in the regs that prevents this for OPP.
 

First find the regulation that covers and explains OPP, I’d be interested to read it myself.

But the Memorandum was pretty clear, it said you had to participate in the manufacture of the part and then went on to give you five ways you could do that, none of those covered already manufactured parts, because how can you participate in the manufacture of an already existing part?

The FAA has been extraordinarily lenient with OPP, but you can’t make things that already exist OPP, you could possibly have an existing part modified. 

‘You guys like Mike Busch, I find little I disagree with him in this article, what I disagree with is that an A&P isn’t allowed to make parts, where we do all of the time, brackets and even wing ribs are often made in doing repairs, but that’s a different subject.

https://resources.savvyaviation.com/wp-content/uploads/articles_eaa/EAA_2011-08_owner-produced-parts.pdf

Edited April 17, 2022 by A64Pilot

[Deb]

2 hours ago, A64Pilot said:

First find the regulation that covers and explains OPP, I’d be interested to read it myself.

14 CFR § 21.9 Replacement and modification articles.

(a) If a person knows, or should know, that a replacement or modification article is reasonably likely to be installed on a type-certificated product, the person may not produce that article unless it is - 

(1) Produced under a type certificate;

(2) Produced under an FAAproduction approval;

(3) A standard part (such as a nut or bolt) manufactured in compliance with a government or established industry specification;

(4) A commercial part as defined in § 21.1 of this part;

(5) Produced by an owner or operator for maintaining or altering that owner or operator's product;

(6) Fabricated by an appropriately rated certificate holder with a quality system, and consumed in the repair or alteration of a product or article in accordance with part 43 of this chapter; or

(7) Produced in any other manner approved by the FAA.

(b) Except as provided in paragraphs (a)(1) through (a)(2) of this section, a person who produces a replacement or modification article for sale may not represent that part as suitable for installation on a type-certificated product.

(c) Except as provided in paragraphs (a)(1) through (a)(2) of this section, a person may not sell or represent an article as suitable for installation on an aircraft type-certificated under §§ 21.25(a)(2) or 21.27 unless that article - 

(1) Was declared surplus by the U.S. Armed Forces, and

(2) Was intended for use on that aircraft model by the U.S. Armed Forces.
 

FAA Legal Interpretation: Byrne Memorandum on owner produced parts:      http://www.velocolutions.com/FAA-owner-manufactured-part.pdf

AC 23-28:
https://www.faa.gov/documentlibrary/media/advisory_circular/ac_23-27.pdf

Some other articles/summaries:   
https://www.csobeech.com/files/FAA-OwnerProducedParts-DonDodge.pdf

https://www.aviationpros.com/home/article/10387511/owner-produced-parts-how-they-affect-maintenance

https://www.cessnaflyer.org/maintenance-tech/item/984-owner-produced-parts-regulations-interpretations-and-applications.html

[A64Pilot]

The only regulation you found was 21.9 which merely mentions an OPP’s existence, but that’s all, however I believe it’s mention in an FAR means it exists legally, so that’s important. I’ve not been able to find an FAR that properly covers an OPP either, doesn’t mean one doesn’t exist, just means I can’t find it if it does. I actually hoped you could find one, my Googlefu is weak

You then found through the FOI request a copy of the original memorandum, which isn’t a regulation, it’s not even an AC, but as it’s all that I have ever been able to find, it’s all I have to go on, and I suspect all there is. It’s all I have been able to find too, the original MFR I have not found.

You also found the AC 23-27 that I quoted to show how a standard part can be replaced, This AC isn’t regulatory, as all AC’s aren’t, it’s advisory, that’s in the title, but again it’s the best we have sometimes, but does it mention OPP?

The rest you found is just people like you or I publishing their opinions on the internet.

However as there seems to be NO regulation describing or controlling an OPP, I guess the best we have to go on is the MFR written by the FAA laywer, and in it it plainly states you have to participate in the manufacturing of the part, no where does it state you can buy an off the shelf part and call it OPP. In fact it goes out of the way to state merely ordering a part doesn’t make it an OPP as you didn’t contribute in the manufacturing.

The genesis of OPP was the Airlines, it gave them the authority to produce parts and keep their aircraft flying, I would assume that’s in their Ops specs and well defined, but as I’ve never worked part 121 I don’t know.

Somehow OPP slipped into GA, but as far as I can find there is no governing regulation, so until the MFR was written, then near as I could tell you could go to NAPA and call anything you wanted to an OPP.

But the MFR is very specific and gives you 5 ways you can make a part OPP, and it’s incredibly lenient in my opinion, but I can’t cut-n-paste for some reason so I’ll attach a screen shot of those 5 ways.

However it should be noted the A&P is required to determine the airworthiness of the part, so if you want him or her to install it, it would help if you could show it conforms to Type Design.

 

 

 

Edited April 17, 2022 by A64Pilot

[carusoam]

10 hours ago, A64Pilot said:

I assume Mooney had them injection molded.

 

assumptions can cause challenges… 

 

We’re going a bit off the reservation here…. OP is a bit aged, and I like donuts…
 

Huge strides in polymer manufacturing were made just about the time Mooneys started to be manufactured…

 

Extrusion and injection molding were blooming in the 1960s…. Thermoforming came after extrusion…

Rubber manufacturing pre-dates those process by a long distance…

Remember… IM takes an existing polymer, melts it, and presses it into a mold to form and cool it…

Rubber molding often requires reaction chemistry first… before molding it… reaction injection molding…. (Kind of specialized)

 

Or like we are discussing… go to the experts that make the device first… (example given McFarlane)

Supply enough detail for them to make the device…

We are relying on them to do a really diligent job of building the article… 

If you are lucky that manufacturer is already familiar with building aviation parts… for serialization record keeping…

Some MSers are very familiar as they have STCs… and build aviation parts for a living… (in their day jobs)…

 

When it comes to making donuts…

The Mooney Mites really need the OPP system to work… (find that thread)

There is plenty of room for improvement when the alternative is nothing….

1950s rubber chemistry, physical properties, and physical dimensions aren’t that magical to a modern rubber chemist…

PP thoughts only, I have only seen some injection molders…and extruders… and mold shops… and die shops… not a polymer chemist…

Best regards,

-a-

[A64Pilot]

Ref the mite, There isn’t supposed to be any differentiation between aircraft, but in truth the older aircraft especially when the manufacturer has been long gone or the aircraft orphaned  most FAA inspectors are more lenient, besides it’s a rare one that actually knows much about the aircraft in question to start with.

However taking an M20 donut as an example where the parts are readily available I believe an inspector wouldn’t be so lenient, just an opinion.

The donuts for the Thrush are molded I believe and there is a difference in failure rates between those manufactured in Summer vs Winter, so the manufacturing is more critical than we may think. It’s not just a chunk of rubber, it’s a chunk of rubber whose composition and hardness etc has set standards.

My neighbor has a Gull wing Stinson, parts as you can imagine are non existent, it’s coming into Annual and the flaps are inop, apparently they are vacuum operated and I’m not sure what it’s going to take to fix them, but am pretty sure we aren’t going to be able to find a serviceable Stinson flap actuator.

I suspect that if for some reason we happen to be visited by an inspector they would be more understanding than they would be for my Mooney if we 

But however the landing gear switch “wheel” is manufactured, hold onto them if the switch goes bad, because I suspect it’s not a standard part, I suspect they  were manufactured specifically for Mooney and I’d hate to put just a plain switch there.

 

Edited April 18, 2022 by A64Pilot

[PT20J]

On 4/17/2022 at 4:28 PM, A64Pilot said:

The only regulation you found was 21.9 which merely mentions an OPP’s existence, but that’s all, however I believe it’s mention in an FAR means it exists legally, so that’s important. I’ve not been able to find an FAR that properly covers an OPP either, doesn’t mean one doesn’t exist, just means I can’t find it if it does. I actually hoped you could find one, my Googlefu is weak

You then found through the FOI request a copy of the original memorandum, which isn’t a regulation, it’s not even an AC, but as it’s all that I have ever been able to find, it’s all I have to go on, and I suspect all there is. It’s all I have been able to find too, the original MFR I have not found.

You also found the AC 23-27 that I quoted to show how a standard part can be replaced, This AC isn’t regulatory, as all AC’s aren’t, it’s advisory, that’s in the title, but again it’s the best we have sometimes, but does it mention OPP?

The rest you found is just people like you or I publishing their opinions on the internet.

However as there seems to be NO regulation describing or controlling an OPP, I guess the best we have to go on is the MFR written by the FAA laywer, and in it it plainly states you have to participate in the manufacturing of the part, no where does it state you can buy an off the shelf part and call it OPP. In fact it goes out of the way to state merely ordering a part doesn’t make it an OPP as you didn’t contribute in the manufacturing.

The genesis of OPP was the Airlines, it gave them the authority to produce parts and keep their aircraft flying, I would assume that’s in their Ops specs and well defined, but as I’ve never worked part 121 I don’t know.

Somehow OPP slipped into GA, but as far as I can find there is no governing regulation, so until the MFR was written, then near as I could tell you could go to NAPA and call anything you wanted to an OPP.

But the MFR is very specific and gives you 5 ways you can make a part OPP, and it’s incredibly lenient in my opinion, but I can’t cut-n-paste for some reason so I’ll attach a screen shot of those 5 ways.

However it should be noted the A&P is required to determine the airworthiness of the part, so if you want him or her to install it, it would help if you could show it conforms to Type Design.

 

 

 

If you are seeking clarity and specificity in the FARs, you will be disappointed. Years ago at a CFI refresher, a former FAA lawyer explained that the FARs (using his exact words) are a "monument to vagueness." He went on to explain that the wording is carefully crafted to give the FAA room to issue legal interpretations to adjust for unforeseen circumstances since to actually change a rule takes years. You cannot completely understand most FARs by reading the rule text. You have to read the preamble to understand the intent of the rule and you have to read any legal interpretations (including the ones that in rare cases countermand a previous interpretation). For instance, a strict reading of the preventive maintenance rule says that the items on the list are the only one's that can be performed by a non-A&P. But, there is a legal interpretation that says these are merely examples and other items of similar nature may be performed. There is a rule that says you cannot fly under IFR unless the pitot/static check is current. But there is a legal interpretation that allows training flights to file a IFR flight plan and obtain a clearance in an airplane without current pitot/static cert. if it operates VMC. I'm sure there are hundreds of other examples.

So, as @Deb took the trouble to point out, 21.9 (a) (5) is the regulatory authority for producing what is commonly referred to as an owner produced part. The details are vague, and if you want more, you will have to look for other guidance. 

Sometimes vagueness is good. AOPA has cautioned about requesting legal interpretations -- sometimes the the FAA jumps on the opportunity to close a commonly accepted loophole. 

Skip

[A64Pilot]

PT20J,

Understood and agree.

However OPP has been interpreted and an MFR written, You must comply to one of the five examples given, although since it was written by a Lawyer even that isn’t plain. It says “the following would tend to indicate” it doesn’t say one of the following five conditions must be met, but I can assure you that’s how it would be enforced.

So as you say it’s up to interpretation, so you then have to fall back on what’s the spirit or intent of the regulation, that’s what makes an IA job so tough, and why you will often get different answers from different IA’s because the honest truth is “it depends”

Spoken by a true lawyer, 

 

Edited April 20, 2022 by A64Pilot

[N201MKTurbo]

At the last maintenance symposium (I hope there are more someday) I attended a session with the FAA person who approves PMA parts and another session about field approvals. The PMA lady spoke a bit about owner produced parts. In both cases they said that the FAA will not approve an OPP or field approval just because you want to save money. If the part is available, or the STC is available, you have to use it. Which begs the question about McFarlane cables. Most people buy them to save money, not because the factory cable is not available. 

The saving grace on most of this stuff is the FAA doesn't check anything anymore. They don't even read 337s unless it requires an FAA signoff, most don't.

I figure that until McFarlane cables start causing problems, the FAA has better things to do.