Do you use nitrogen?

[avbug]

True. A certificate holder can obtain authorization for pilots to perform certain items of preventative maintenance. It does not need to obtain an authorization to do things like add oil, which is NOT an item of maintenance preventative or otherwise.

Again, you are wrong, which is consistant...as you've been wrong about everything you've stated from the outset. Adding oil may be complex in nature, and for a certificate holder, may require an authorization and documentation of training. The Piaggio Avanti, for example, requires that one climb onto the wing, remove fifteen self-locking internally threaded (and expensive) screws, remove a panel, and remove a cannon plug before unlocking and removing the dipstick to check the oil...which must be done within 10 minutes of engine shutdown. Not quite the same as dropping a quart in your 172 is it, pal? Add too much, blow a seal, lose the engine...not good. If operated by a certificate holder, adding oil requires FAA approval, an approved training program, certification of completion of that training program, and pilot approval to check or service the oil.

Numerous aircraft require more than flipping a latch and unscrewing a dipstick to check fluids or service them...but your experience with your examiner in your 172, over which you won't be losing any sleep, has made you an expert on that subject, so we needn't say more. Need we?

etc etc.

Irrelevent, as is the rest of your rambling about magnafluxing and so on. The question is the legality, not whether I understand the proper way to do it or have the tools.

Hardly irrelevant, as the question of legality with respect to your ability to perform any given operation demands that you meet all the requirements of the operation. If changing a tire requires that the wheel halves and bolts be magnafluxed, then it must be done, and if you're not qualified to do it, then you can't do it, and you can't change that wheel out. It's very relevant, indeed. You need to know this from reading the current publications for that wheel assembly...all of them. This includes wheel manufacturer, tire manufacturer, brake manufacturer, and airframe manufacturer, as well as applicable airworthiness directives, and in most cases, research in the aircraft logs to determine cycles, previous work and compliance, etc. All of this before you can touch the part. Very relevant.

W(h)eather you have the calibrated tools called for in the approved documents, know how to use them, have the training and experience to perform the work to industry standard, and the ability to execute all the necessary documentation, is extremely relevant, as it's the crux of the legality of the matter. But you knew that too, didn't you, expert?

Sure. It requires a maintenance entry under 121, because that's part of our approved maintenance program. It requires a maintenance entry if you have to remove a panel or cowl. Otherwise, it's not. It's routine servicing, no different then adding fuel.

In a piston engine, true. Not in in a turbine engine.

49-31-02

AD 49-31-02 involves installation of a placard. It requires one-time compliance, in installing the placard. It does NOT require compliance or a log entry during fueling, as compliance is satisfied by installing the placard. What AD's have you located specifically regarding fueling the airplane? I'll give you one. AD 60-13-03 requires compliance at each fueling in certain Lockheed aircraft...and if compliance is necessary, a maintenance entry is necessary. Fly anything with a required fuel additive? Is it mandated by an AD? Even if it isn't, is it blended to spec by weight or percentage, and have you made that determination? Does an AD require the use of certain fuel tank treatments in your aircraft, and if they've been done, have you checked to determine the legality of adding fuel and by what percentage you can do the mix? You knew about that, didn't you? If you didn't and screwed up, you were unable to perform proper servicing of the aircraft, allowed in theory by Appendix A or any other location...and it needed to be done by a certificated mechanic. But you knew that too, right?

Flown a Mooney? Know about AD 2004-25-04 and compliance with each fueling, depending on the specifics spelled out in the AD? Depending on your AMOC, a log entry may be required every time you fuel or preflight...and that for your "routine servicing." Go figure.

But this thread isn't about fueling or hydraulic fluid, though you've certainly attempted to make it so. It's about Nitrogen. Nobody's addressed this regulation so far, but 14 CFR 25.733(e) specifically requires nitrogen, as a function of certification (and subsequent airworthiness for aircraft certificated under Part 25) in large aircraft over 75,000 lbs:

(e) For an airplane with a maximum certificated takeoff weight of more than 75,000 pounds, tires mounted on braked wheels must be inflated with dry nitrogen or other gases shown to be inert so that the gas mixture in the tire does not contain oxygen in excess of 5 percent by volume, unless it can be shown that the tire liner material will not produce a volatile gas when heated or that means are provided to prevent tire temperatures from reaching unsafe levels.

Moving right along...

Anther one I pulled out of "thin air" to support a "100 % incorrect point"

Your point was that...

Plenty of "certified mechanics" have killed themselves by attaching unregulated 3000 psi nitrogen bottles to aircraft wheel assemblies.

To which I correctly replied that this is an extremely rare occurence.

Of course, the article that made you an authority and expert on the subject claims that...

Thousands of airplane tires are inflated during routine maintenance each day around the world. On occasion, a mechanic or other ground service employee has been severely or fatally injured in an explosion caused by use of unregulated pressure from an air or nitrogen tank. The latest reported incident occurred in 1998 when a mechanic was inflating a nose wheel/tire assembly on a 737 airplane. A total of five similar incidents have been reported as the cause of severe injury or death to maintenance personnel

According to you, plenty of certificated mechanics die from this action...your point is irelevant because it doesn't apply to anything under discussion...nevertheless, you introduced it...plenty of mechanics die doing foolish things during routine servicing. According to the evidence you introduced, thousands of tires are serviced daily. Being a multiple of a thousand, let's stick with the minimum number of two thousand, and multiply that by 365, as these thousands are being serviced daily. This gives us a minimum of seven hundred thirty thousand tires serviced annually, times eight years, as the reported 737 tire explosion occured in 1998...in the intervening years, eight in total, we can see a minimum of fifty eight million, four hundred thousand tire inflations by maintenance personnel. Of these, five have been reported to have been done directly from the bottle, for a microscopic rate that apparently establishes your definition of "plenty."

Your definitions are clearly skewed, as are your examples to support incorrect points, your incorrect use of inappropriate and inapplicable airworthiness directives that are off-topic and irrelevant (did you read them?). The one link you did provide includes one paragraph of use, which does apply to the topic at hand, as follows:

Inflating wheel/tire assemblies only with nitrogen.
Tires must be initially inflated only with nitrogen. However, air can be used to top off a low-pressure tire if the airplane is in a location where nitrogen is not readily available, provided that the oxygen content does not exceed 5 percent by volume. Optional procedures for ensuring that the oxygen content in the tire will not exceed 5 percent are typically found in chapter 12 of the AMM. These procedures include a table that lists the maximum refill pressure versus the initial tire inflation pressure. The sum of all air pressures added to a given tire cannot exceed the pressure shown in the table for the corresponding initial inflation pressure.

Thanks for playing.

 

[avbug]

From Advisory Circular AC 43-12A, Preventative Maintenance:

4. PREVENTIVE MAINTENANCE.

a. The holders of mechanic and repairman certificates, persons working under the supervision of these mechanics and repairmen, repair stations certificated under Part 145, and air carriers certificated under Parts 121, 127, and 135, are authorized to perform preventive maintenance. These persons are also authorized to perform other maintenance. Therefore, it is of little consequence to them how a particular function is classified, since they are authorized to perform the function as either preventive maintenance or as other maintenance. Further, the procedures used in approving for return to service and recording are identical. This AC will, therefore, consider preventive maintenance from the owners/operators point of view.

b. FAR Part 1, Section 1.1, defines preventive maintenance as "...simple or minor preservation operations and the replacement of small standard parts not involving complete assembly operations."

(1) FAR Part 43, Appendix A, paragraph (c) contains the list of those functions determined by the FAA to meet this definition. If a function does not appear in this list, it is not preventive maintenance. Further, because of differences in aircraft, a function may be preventive maintenance on one aircraft and not on another. To provide for this, paragraph (c) contains the limitation, "Provided it does not involve complex assembly operations" on the aircraft involved. Owners and pilots must use good judgment in determining that a specific function may appropriately be classified as preventive maintenance.



--Merely because an item is listed in Appendix A, does NOT mean that a pilot can perform that function as preventative maintenance!!




From FAA Publication P-8740-4A, Safety Guide for Private Aircraft Owners:

12. PREVENTIVE MAINTENANCE
"Preventive maintenance" means simple or minor preservation operations or the replacement of small standard parts, not involving complex assembly operations.

a. Who May Perform Preventive Maintenance
The holder of a pilot certificate issued under Part 61 of the Federal Aviation Regulations may perform preventive maintenance on any aircraft owned or operated by him that is not used in air carrier service (ref. FAR 43.3(h)). All other maintenance, repairs, rebuilding, or alterations may be performed by persons authorized to do so by the Federal Aviation Administration.

b. Methods, Techniques, and Practices
When performing any of the preventive maintenance items that are allowed, you must use methods, techniques, and practices acceptable to the FAA. You must do the work in such a manner and use materials of such a quality, that the condition of the aircraft, airframe, aircraft engine, propeller, or appliance worked on will be at least equal to its original or properly altered condition. As modern day aircraft becomes more and more intricately engineered, preventive maintenance on some of the aircraft components is an exacting job, even for the experienced aircraft mechanic.



From 14 CFR 1.1, Definitions:

Preventive maintenance means simple or minor preservation operations and the replacement of small standard parts not involving complex assembly operations.

Standard parts are defined by 14 CFR 21.321(b)(3) as included in Class III parts:

(3) A Class III product is any part or component which is not a Class I or Class II product and includes standard parts, i.e., those designated as AN, NAS, SAE, etc.

Standard Parts are also defined as spelled out in the Federal Register Preamble (Volume 62, number 43), dated March 5, 1997:

"Standard part" is not otherwise defined in Title 14. Section 21.303(b)(4) has come to be understood by the aviation and manufacturing public as meaning a part, the specification for which has been published by a standard setting organization or by the U.S. government, and the FAA has traditionally regulated parts production with that understanding. Examples of such "traditional" standard part specifications include National Aerospace Standards (NAS), Air Force-Navy Aeronautical Standard (AN), Society of Automotive Engineers (SAE), SAE Aerospace Standard (AS), and Military Standard (MS). The FAA will continue to consider parts conforming to these specifications as standard parts.

Therefore, preventative maintenance means simple or minor preservation and replacement of small standard parts designated by an AN, NAS, SAE type standard designation...not anything involving a complex assembly. One should note that complex assembly doesn't mean the difficulty of assembly, as some often erroneously assume. Complexity of assembly involves the type of assembly and the complexity of its' nature, or overall design.

Note the following as indicated in Advisory Circular AC 21-29B Detecting and Reporting Suspected Unapproved Parts:

Note: Standard parts are not required to be produced under an FAA Approved Production Inspection System, therefore it is incumbent upon the installer (and the producer) to determine that the part conforms. The part must be identified as part of the approved type design or found to be acceptable for installation under part 43. Refer to AC 20-62, for additional guidance on this matter.

This places an additional burden on the individual performing preventative maintenance to determine that a part conforms to published standards. Merely because one has purchased a locknut from Aircraft Spruce or some other retailer or supplier, does not mean the part is a valid conforming part; if you torque, install or use that part in any way, you are responsible for compliance and the authenticity of that part, legally. If that part should fail, you are also responsible for the failure. A seldom appreciated aspect of preventative maintenance. You must be able to verify parts compliance to legally perform the function, right down to the cotter pin you use.

Additionally, to be legal, you must be able to determine that a standard part which is authentic is in compliance. For example, a fiberlock nut must not be turnable with the fingers once the fiber material meets the bolt threads. If the part is authentic, but doesn't meet specification or industry standards (see AC 43.13), the part isn't legal, the work isn't legal, and the operation may not be performed. If the person performing the preventative maintenance (eg, private pilot, for example) cannot make this determination, the work may not legaly be performed.

More to legality than may meet the eye.

Note the following paragraph from the same Preamble cited above:

It is important to remember that 14 CFR Part 21 § 21.303 deals with the production of parts for sale for installations on type certificated products. Installation of replacement or modification parts including owner/operator-produced and standard parts, must be accomplished in compliance with part 43 of Title 14 of the CFR (Part 43). Generally, a standard part may be replaced with an identical standard part, in accordance with the manufacturers maintenance instructions, without a further demonstration of compliance with the airworthiness regulations. Substitution of a standard part with another would require a demonstration of acceptability in accordance with part 43.

Swapping one type of fastener for another, such as using a castelated nut in place of a fiberlock or visa versa, will require a demonstration of acceptability, and until that's accomplished, the part remains unairworthy...even though both parts may be standard and authentic per spec.

The point is that more exists with relation to maintenance than merely reading appendix A and executing what's listed there. An item may be listed, but you may not be able to do it...and if you do, there's a whole lot more involved in being legal in doing it than you may think.

 

[avbug]

etc etc.

Irrelevent, as is the rest of your rambling about magnafluxing and so on. The question is the legality, not whether I understand the proper way to do it or have the tools.

Again, to touch on your assertion that this is a question of legality...the following addresses the minimum that is required to be legal...including the fact that merely because an item is listed in Appendix A, doesn't mean you can do it, legally...

AC 43-12A:

b. FAR Part 1, Section 1.1, defines preventive maintenance as "...simple or minor preservation operations and the replacement of small standard parts not involving complete assembly operations."

(1) FAR Part 43, Appendix A, paragraph (c) contains the list of those functions determined by the FAA to meet this definition. If a function does not appear in this list, it is not preventive maintenance. Further, because of differences in aircraft, a function may be preventive maintenance on one aircraft and not on another. To provide for this, paragraph (c) contains the limitation, "Provided it does not involve complex assembly operations" on the aircraft involved. Owners and pilots must use good judgment in determining that a specific function may appropriately be classified as preventive maintenance.

(2) A pilot may not perform preventive maintenance on aircraft used under Parts 121, 127, or 135, even when the pilot owns the aircraft.

c. Persons authorized to perform preventive maintenance. In addition to those persons listed in paragraph 4a of this AC, Section 43.3(g) authorizes the holder of a pilot certificate issued under Part 61 to perform preventive maintenance. Section 43.7 limits the privilege to persons holding at least a private pilot certificate and Section 43.5 prohibits operation of the aircraft unless approved for return to service. Further, pilots may only approve for return to service preventive maintenance which they themselves have accomplished.

d. Applicable performance standards.

(1) FAR 43.13 requires preventive maintenance to be done using methods, techniques, and practices acceptable to the Administrator. These are normally set forth in the manufacturer's maintenance manuals; however, some may be found in ACs published by the FAA.

(2) FAR 43.13 requires the use of the tools, equipment, and test apparatus necessary to assure completion of the work in accordance with accepted industry practices. This means that the proper tools and test apparatus must be used. Normally these are listed as part of any FAA-approved manufacturer's maintenance literature.

(3) FAR 43.13 also requires that any special equipment recommended by the manufacturer or its equivalent must be used in a manner acceptable to the Administrator. This provision is more directly applicable to maintenance than preventive maintenance. However, it may come into play. Therefore, owners and pilots should be aware of it.

(4) Additionally, Section 43.13 requires that the work performed and the materials used are to be such as to ensure that, when the work is finished, the item worked on is at least equal to its original condition. Caution must be exercised because some functions which appear to be simple tasks may, in fact, be quite complicated. Care should be taken to ensure that the manufacturer's instructions are understood, the function is within the individual's capability, within the definition of preventive maintenance, and that it is listed in paragraph (c) of Appendix A of Part 43.

e. Recording preventive maintenance. Preventive maintenance must be recorded in accordance with Section 43.9 of FAR Part 43. This is done by entering in the maintenance record, of the item worked on, the following:

(1) "A description (or reference to data acceptable to the Administrator) of the work performed." This should indicate what was done and how it was done. This is normally quite simple for preventive maintenance; however, if the description is extensive, reference to documents containing that description is acceptable. These may be manufacturer's manuals, ACs, or other documents or references containing data acceptable to the Administrator. If documents other than types which are in common use are referenced, the document should be made a part of the maintenance record, as required by Section 43.9(a)(1).

(2) "The date of completion of the work performed." This is self explanatory and is the date on which the entry is made, as required by Section 43.9(a)(2).

(3) The kind of airman certificate exercised. When preventive maintenance is performed as authorized in Section 43.3(g), the certificate may be indicated in any manner which would be clear to the reader. For example: PP, CP, or ATP might be used to indicate private, commercial, or airline transport pilot, respectively. The certificate number is that number displayed on the certificate being exercised. Affixing a signature to the entry, which describes the work accomplished, constitutes approval for return to service, as required by Section 43.9(a)(4).

NOTE: Since owners/pilots are not authorized to approve work accomplished by others, Section 43.9(a)(3) is not applicable when preventive maintenance is performed by the holder of a pilot's certificate. The holder of the pilot's certificate doing the work is the only person who can sign the approval for return to service.

 

[ackattacker]

I have stopped reading. You've gone over the top.

The point is not that you're wrong, you're not. The problem is you're an A$$. I'm guessing this is not the first time someone has said that to you. The poster asked a simple question. He walked into an FBO, after presumably flying in on a normal GA or small jet type aircraft, presumably with normal aircraft type tires. You know, the kind with valve stems sticking out of them where you can get to 'em.

He asked the FBO if he could fill his tires with nitrogen. They said that using the nitrogen required a mechanic. He now asks the board "hey, is this right or are they feeding me a line of BS? Is there something in the regs which specifically prohibits me (a pilot) from filling these tires with nitrogen (as opposed to air)?"

I answered that no, the regs don't make a differentiation between filling a tire with air and filling it with nitrogen. The FBO is feeding you a line of BS, because the regs don't in general require a mechanic to fill a tire. In fact, the regs don't actually mention filling a tire at all. That is the end of story, all a normal person needs to know.

I *incorrectly* stated that it would be an item of preventative maintenance. In fact, as you have (eventually) pointed out, it is not *normally* an item of preventative maintenance, although it could be if it involved some more complex steps. Normally, filling a tire does not even make it the level of "preventative maintenance".

Your response to my post was both condescending and confusing. You brought transport category aircraft into it, approved maintenance programs, and a bunch of discussion about all the detailed technical knowledge you need to perform a full-on inspection and repair of a wheel assembly. Your first post strongly implied that a mechanic was *normally* required to fill a tire with either air or nitrogen, which I naturally took issue with.

Let me ask you a question: If someone asks you a simple question, say "is the sky blue", is the answer "yes"? Or is a 15 page rambling discussion about how the sky may or may not be blue depending upon your altitude and whether or not a volcano in Indonesia just erupted?

If I answer "yes, the sky is blue" does that mean that I'm too stupid to possibly understand all the technical ramifications of Rayleigh scattering and atmospheric science?

 

[ackattacker]

According to you, plenty of certificated mechanics die from this action...

Too me, even one mechanic dying from adding nitrogen to wheel is "plenty" to illustrate the point that it can be dangerous if done improperly. I don't think that's a skewed perspective. You wouldn't either if you were the one with your arms blown off.

You are so argumentative that you didn't even realize that I introduced it in support of your point that some items of maintenance should be done by qualified and trained individuals even if the regulations permit otherwise. You actually accused me of making it up.

 

[mtrv]

Well-----------

Thank god, that I'm legal to put nitrogen in my airplanes tires; and the fact that I have nitrogen tanks along with gauges to regulate the pressure; and have been using nitrogen for business purpose's at least 30 years or so.

I feel good!

 

[The_Russian]

The point is not that you're wrong, you're not. The problem is you're an A$$.

Avbug and A-Squared. One in the same?

 

[avbug]

The poster asked a simple question. He walked into an FBO, after presumably flying in on a normal GA or small jet type aircraft, presumably with normal aircraft type tires. You know, the kind with valve stems sticking out of them where you can get to 'em.

He asked the FBO if he could fill his tires with nitrogen. They said that using the nitrogen required a mechanic. He now asks the board "hey, is this right or are they feeding me a line of BS? Is there something in the regs which specifically prohibits me (a pilot) from filling these tires with nitrogen (as opposed to air)?"

I answered that no, the regs don't make a differentiation between filling a tire with air and filling it with nitrogen. The FBO is feeding you a line of BS, because the regs don't in general require a mechanic to fill a tire. In fact, the regs don't actually mention filling a tire at all. That is the end of story, all a normal person needs to know.

I *incorrectly* stated that it would be an item of preventative maintenance. In fact, as you have (eventually) pointed out, it is not *normally* an item of preventative maintenance, although it could be if it involved some more complex steps. Normally, filling a tire does not even make it the level of "preventative maintenance".

The truth is that filling a tire might be nothing, or may be a very big deal. Aircraft wheel assemblies are not car tires, and require special handling and attention. I did reply (#28) early to the post; numerous posters got carried away on incorrect points and information, missing the legalities, reasons, and purpose of nitrogen. You got carried away on multiple incorrect tangents regarding legalities of various forms of maintenance, and repeatedly attempted to defend your uninformed positions. Had you not been so bent on opening your mouth and appearing the fool, the thread would have been considerably shorter.

The regulations, advisory circulars, airworthiness directives, and approved data for numerous aircraft applications do make a difference, and do specify the use of nitrogen. You answered incorrectly when you stated that the regulations do not specify the use of nitrogen. As we have shown, numerous references are required to understand the regulation properly. Part 43 requires that work be done in accordance with approved data, and if an approved manufacturer maintenance manual or other aproved technical data dictates the use of nitrogen, then the regulation per Part 43 requires the use of nitrogen. Likewise an AD, or even an advisory circular, as required per Part 39 and Part 43 respectively, often serve this same purpose. We have seen that for some aircraft, the certification regulations themselves require the use of nitrogen...and we have seen in the same regulation the reason thereof.

Ultimately, even in your most basic point, your reply you have just cited, you were wrong...and can't even admit that much. I'm not particularly concerned that you wise up...clearly you either can't, or won't. However, I'm concerned that someone may be foolish enough to listen to you, and thereby get themselves, or their student, or even an unwitting third party, in trouble.

So yes, the regulations do frequently address not only what goes in the wheel assy, but how it's done, pressures, torques, inspection proceedures, practices and techniques, and standards for completion...right down to the percentage of oxygen that may be inside the tube or tire. This regulatory information may be in the Code of Federal Regulations, or any publication required to be used by the CFR...including AC's (eg, AC 43.13, etc) AD's, Service Bulletins, Manufacturers approved maintenance publications or instructions for continued airworthiness, and so forth.

You should take some time and get more familiar with Part 43...you're just as beholden to it as any certificated mechanic, and held to the same standard.

The original poster requested nitrogen from the FBO. The FBO advised that a mechanic was required to put in the nitrogen. Most likely the FBO isn't going to allow an unknown person not employed by the FBO to use their nitrogen; I wouldn't either. Liability is a big concern. The FBO may have a policy regarding the use of their nitrogen equipment by uncertificated persons or persons not employed and trained by the FBO to use that equipment. The equipment may belong to a maintenance contractor that only allows their mechanics to use it. The counter personnel may have been using their best guess. No information there has been provided, so we really can't say. The FBO may have been quite right with respect to their insurance, policy, or even with respect to the operation intended...bottom line is that it's their nitrogen, it's their equipment, it's their call.

You brought transport category aircraft into it, approved maintenance programs, and a bunch of discussion about all the detailed technical knowledge you need to perform a full-on inspection and repair of a wheel assembly. Your first post strongly implied that a mechanic was *normally* required to fill a tire with either air or nitrogen, which I naturally took issue with.

*With which I naturally took issue.* But as you like it.

Transport category aircraft because you adamantly insisted that no regulation requires the use of nitrogen in an aircraft tire. I cited a regulation that does.

Approved maintenance documents because the regulations require all work to be done in accordance with approved data (that pesky Part 43, again), which means that the regulation requires the use of nitrogen where the manufacturer approved data calls for it.

A discussion regarding inspection of wheel assemblies because any time you service that tire or wheel, it should be closely inspected...something you may not do on your car, but should certainly do on your aircraft...and cited points regarding which you were clearly not aware. Further, as you introduced the topic of pilots performing owner maintenance in accordance with Appendix A of Part 43, I addressed the reasons why your points were wrong...including a frequent need to perform advanced technical inspections of wheel assemblies when doing something as simple as changing a tire.

Each point discussed only because you brought it up.

And no, the sky is not blue. At some altitudes it may appear so, under certain circumstances...but you can get the technicalities from those energetic souls here that managed to go to school in their youth.

You've concluded post after post challenging me to prove you wrong...it's not challenge as you're wrong virtually all the time. You spend your time thinking up stupid questions and answers, and upon your invitation, so long as I've nothing better to do, I'll spend spare time explaining why you're wrong. Again. And again. And again. Have a ball.

 

[avbug]

Avbug and A-Squared. One in the same?

Now, there's an original idea.

No, not even close.

 

[ackattacker]

You answered incorrectly when you stated that the regulations do not specify the use of nitrogen.

I never stated any such thing. I stated the regulations don't differentiate between who is authorized to fill a tire with air and who is authorized to fill a tire with nitrogen. I never claimed the regulations fail to specify when one or the other is required, yet you seem to feel that was my point? Presumably the poster who wanted to fill his tires with nitrogen wanted to do so because it was required for his aircraft.

The original poster requested nitrogen from the FBO. The FBO advised that a mechanic was required to put in the nitrogen. Most likely the FBO isn't going to allow an unknown person not employed by the FBO to use their nitrogen; I wouldn't either. Liability is a big concern. The FBO may have a policy regarding the use of their nitrogen equipment by uncertificated persons or persons not employed and trained by the FBO to use that equipment. The equipment may belong to a maintenance contractor that only allows their mechanics to use it. The counter personnel may have been using their best guess. No information there has been provided, so we really can't say. The FBO may have been quite right with respect to their insurance, policy, or even with respect to the operation intended...bottom line is that it's their nitrogen, it's their equipment, it's their call.

A point which I made much more succinctly in my first post when I said "the nitrogen equipment is typically under the control of mechanics and they don't want you touching their stuff".

Transport category aircraft because you adamantly insisted that no regulation requires the use of nitrogen in an aircraft tire. I cited a regulation that does.

A never insisted any such thing adamantly or otherwise. That would be pretty stupid of me to argue, I agree. Where did I say that? It's easy to argue endlessly when you are writing both sides.

And no, the sky is not blue. At some altitudes it may appear so, under certain circumstances...but you can get the technicalities from those energetic souls here that managed to go to school in their youth.

Well, there you go. You did answer my question. I didn't ask if the sky was blue. I asked if you would give some sort of ridiculously technical, borish answer to such a simple yes/no question. The answer is that you would.