[VETE76]

what, if any, avionics has to be TSO for IFR cert. in my
RV7?

 

[Smilin' Jack]

You asked a good question concerning TSO, Beside the pitot static system check required. I am not sure that any of the equipment has to be TSO'd except the transponder. Or that you are not flying in RVSM airspace.

I'll do some research but the only thing I have seen so far is like I am considering a Skyview package, TSO Transponder Mode S Garmin, GPS in the Skyview package and I would need a backup EFIS display or artifical Horizon,
and a DG, Turn Cordinator, and a mag compass or vertical compass. But if I am anticipating on shooting approaches I have to have a VOR or LOC or some other method of shooting an approach incase the GPS quits or is taken down by the FED's. So then that requires a VOR receiver and head.
All your standard lights are needed too.
I am not even sure about the transponder having to be TSO'd. I am sure there are some avionics guys out there with the answer.

Smilin' Jack

 

[Brantel]

Strictly talking GPS, NAV and Xponder here:

It is my understanding that nothing has to be TSO'd in your experimental airplane to fly IFR but there are rules about how certain things must meet the TSO standards for their intended purpose. The problem is there is nothing that meets the TSO standards on the market that is not TSO'd....

They got us by the nads....until someone capitalizes on the market available to non-TSO'd navigation sources that meet the standards. It will be a good day for us when someone does this!

 

[apkp777]

A.I.M 1-18-19

Just looking over the AIM. Ch 1-18-19, to use a GPS for IFR, it "must be approved" I.A.W. T.S.O. C-129. and that the installation be done I.A.W. AC 20-130A.

According to FAR 91.215 Transponders must "meet the performance and environmental requirements" of TSO C74b,c or c112.

 

[s24789]

Install at least a vor and transponder. The vor is so you meet the legal rules for IFR. The government knows that everyone flies by GPS legal or not. One thing to watch out for though is interference with GPS signals from of emmisions. In the Tampa area it is very frequent to lose GPS reception.

 

[Bob Axsom]

Well maybe not everyone

Install at least a vor and transponder. The vor is so you meet the legal rules for IFR. The government knows that everyone flies by GPS legal or not. One thing to watch out for though is interference with GPS signals from of emmisions. In the Tampa area it is very frequent to lose GPS reception.

I have two NAV radios and VOR/LOC/GS instruments with flip-flop frequency capability and all my instrument approaches are flown using those instruments.

Bob Axsom

 

[craigvince]

None of your equipment is required to be TSO'd.

The transponder must have been manufactured to TSO standards, but doesn't need to have an actual TSO. So, if Dynon says their transponder meets the same requirements as a TSO'd transponder, you can legally fly IFR with it.

There is no requirement to have any specific navigation equipment, as long as the equipment you're using is appropriate for the type of navigation you intend to use. In other words, you could theoretically fly IFR using only a Garmin 420 GPS/Com, for example. No VOR, DME, ADF, etc is required. The previous language in the FAR stating something about "ground based navigation" has been removed to allow GPS as a primary and sole source of navigation.

Remember, we're talking legally here. I'm not suggesting that you should do so. You're the one flying the bird. You decide how much IFR you're willing to fly with as little or much equipment as you have. Personally, I'd want either two separate nav/vor receivers with indicators, or a GPS plus one alternative.

 

[Walt]

None of your equipment is required to be TSO'd.

The transponder must have been manufactured to TSO standards, but doesn't need to have an actual TSO. So, if Dynon says their transponder meets the same requirements as a TSO'd transponder, you can legally fly IFR with it.

This may be technically correct, however, I doubt you will find anyone to certify your non TSO'd transponder as required by 91.413 (24 month checks). Without the TSO shops are unable to determine if a unit actually meets the TSO.

 

[Bob Axsom]

Every two years

Every even numbered year in November I taxi over to Wings Avionics and get my static system, transponder and encoder checked and every month I cross check the two NAV systems with a common antenna against each other reading the racial from the DAK VOR on the ground (135 deg on both yesterday). The transponder is a Terra and it has such a powerful output they have to account for it in the equipment used by them.

Your operating limitations will say something about not being able to fly in IMC until equipment meeting the requirements of some FAA document are complied with. You comply with those requirements and get it documented in the aircraft logs, etc. I believe you are in compliance with the requirements but I do not claim to be an authority on it - I'm just a instrument rated private pilot aircraft builder with a repairman certificate and that's how I do it.

Bob Axsom

 

[Flying Scotsman]

This may be technically correct, however, I doubt you will find anyone to certify your non TSO'd transponder as required by 91.413 (24 month checks). Without the TSO shops are unable to determine if a unit actually meets the TSO.

91.413 says that the transponder has to be inspected every 24 months and found to comply with Appendices E and F of Part 43. Going there, I didn't see anything about the TSO at all, but rather a whole series of "Verify that ________". I could have missed the reference to the TSO, of course.

(a) No persons may use an ATC transponder that is specified in 91.215(a), 121.345(c), or Sec. 135.143(c) of this chapter unless, within the preceding 24 calendar months, the ATC transponder has been tested and inspected and found to comply with Appendix F of part 43 of this chapter; and

(b) Following any installation or maintenance on an ATC transponder where data correspondence error could be introduced, the integrated system has been tested, inspected, and found to comply with paragraph (c), Appendix E, of part 43 of this chapter.

​

and then, e.g., Appendix F starts like this

The ATC transponder tests required by Sec. 91.413 of this chapter may be conducted using a bench check or portable test equipment and must meet the requirements prescribed in paragraphs (a) through (j) of this appendix. If portable test equipment with appropriate coupling to the aircraft antenna system is used, operate the test equipment for ATCRBS transponders at a nominal rate of 235 interrogations per second to avoid possible ATCRBS interference. Operate the test equipment at a nominal rate of 50 Mode S interrogations per second for Mode S. An additional 3 dB loss is allowed to compensate for antenna coupling errors during receiver sensitivity measurements conducted in accordance with paragraph (c)(1) when using portable test equipment.
(a) Radio Reply Frequency:
(1) For all classes of ATCRBS transponders, interrogate the transponder and verify that the reply frequency is 1090?3 Megahertz (MHz).
​

and has a laundry list of things to verify.

 

[Walt]

The transponder is a Terra and it has such a powerful output they have to account for it in the equipment used by them.

The Terra is rated at 200 watts like most other class A transponders, they seldom put out more and generally less.

 

[Walt]

91.413 says that the transponder has to be inspected every 24 months and found to comply with Appendices E and F of Part 43. Going there, I didn't see anything about the TSO at all, but rather a whole series of "Verify that ________". I could have missed the reference to the TSO, of course.

(a) No persons may use an ATC transponder that is specified in 91.215(a), 121.345(c), or Sec. 135.143(c) of this chapter unless, within the preceding 24 calendar months, the ATC transponder has been tested and inspected and found to comply with Appendix F of part 43 of this chapter; and

​

Go back and read 91.215:

? 91.215 ATC transponder and altitude reporting equipment and use.
(a) All airspace: U.S.-registered civil aircraft. For operations not conducted under part 121 or 135 of this chapter, ATC transponder equipment installed must meet the performance and environmental requirements of any class of TSO-C74b (Mode A) or any class of TSO-C74c (Mode A with altitude reporting capability) as appropriate, or the appropriate class of TSO-C112 (Mode S).​

 

[Flying Scotsman]

Go back and read 91.215:

? 91.215 ATC transponder and altitude reporting equipment and use.
(a) All airspace: U.S.-registered civil aircraft. For operations not conducted under part 121 or 135 of this chapter, ATC transponder equipment installed must meet the performance and environmental requirements of any class of TSO-C74b (Mode A) or any class of TSO-C74c (Mode A with altitude reporting capability) as appropriate, or the appropriate class of TSO-C112 (Mode S).

Yes, precisely...but that's exactly what people have been saying...that a manufacturer can make a device that meets the TSO, and thus it's legal. I don't see where the previously mentioned FAR requires that the inspector verify or validate all of the requirements in the TSO. Do they normally verify compliance to requirements for +15G shock tests? What about testing at -15 degrees C or +40 deg C? Do you test for waterproofness? Overvoltage?

As I read it, and I could be very wrong (I often am), the biannual inspection requirements as listed in 91.413 and the appendices are quite limited, and contain no references to any TSO. Compliance to the TSO is the job of the manufacturer and installer.

(I note that as far as I can determine, everybody who is making transponders, including those for experimental markets, has a statement that they meet the TSO...but I'm just poking at the *biannual inspection* requirements, and whether, say, a homegrown transponder is acceptable. I believe that, as long as the device was built and tested by the garage electronics guy to the TSO requirements, it's good to go...).

There may be a semantic issue here, too...what do we mean by the use of the pseudo-verb "TSO'd", as in "The GNS-430W is a TSO'd device"? Is that just a colloquialism? Or is there an actual piece of paper from the FAA or some other certifying body that is *required* to assert compliance with the TSO?

 

[craigvince]

... must meet the performance and environmental requirements of any class of TSO-C74b (Mode A) or any class of TSO-C74c ....

Doesn't say it has to actually be TSO'd, just that it meets the requirements of a TSO. The manufacturer (Dynon, for example) can say it meets the requirements, even if they haven't actually spent the hundreds of thousands of dollars to get an actual TSO.

 

[Walt]

Yes, precisely...but that's exactly what people have been saying...that a manufacturer can make a device that meets the TSO, and thus it's legal. I don't see where the previously mentioned FAR requires that the inspector verify or validate all of the requirements in the TSO. Do they normally verify compliance to requirements for +15G shock tests? What about testing at -15 degrees C or +40 deg C? Do you test for waterproofness? Overvoltage?

As I read it, and I could be very wrong (I often am), the biannual inspection requirements as listed in 91.413 and the appendices are quite limited, and contain no references to any TSO. Compliance to the TSO is the job of the manufacturer and installer.

(I note that as far as I can determine, everybody who is making transponders, including those for experimental markets, has a statement that they meet the TSO...but I'm just poking at the *biannual inspection* requirements, and whether, say, a homegrown transponder is acceptable. I believe that, as long as the device was built and tested by the garage electronics guy to the TSO requirements, it's good to go...).

There may be a semantic issue here, too...what do we mean by the use of the pseudo-verb "TSO'd", as in "The GNS-430W is a TSO'd device"? Is that just a colloquialism? Or is there an actual piece of paper from the FAA or some other certifying body that is *required* to assert compliance with the TSO?

Perhaps this is all a mute point due to the fact that (as far as I know) there are no "non TSO'd" transponders available. But if there were, I doubt you would find a repair station to certify or install it (even if you install it yourself you still must have a certified repair station do the initial and 24 mth checks).

All TSO'd equipment carries a TSO label certifiying to which TSO the unit was tested to

Doesn't say it has to actually be TSO'd, just that it meets the requirements of a TSO. The manufacturer (Dynon, for example) can say it meets the requirements, even if they haven't actually spent the hundreds of thousands of dollars to get an actual TSO.

A certifying repair station has no way to tell or verify that a unit meets a TSO so it relies on the equipment manufacturer for this. If it doesn't have a TSO authorization tag on it than there is no way to confirm it meets the requirements. Reading it in the sales literature won't work as far as the FAA is concerned. Repair stations are an extension of the FAA and operate under strict guidelines that hold them accountable to all applicable FAR's.

 

[Flying Scotsman]

Perhaps this is all a mute point due to the fact that (as far as I know) there are no "non TSO'd" transponders available. But if there were, I doubt you would find a repair station to certify or install it (even if you install it yourself you still must have a certified repair station do the initial and 24 mth checks).

All TSO'd equipment carries a TSO label certifiying to which TSO the unit was tested to



A certifying repair station has no way to tell or verify that a unit meets a TSO so it relies on the equipment manufacturer for this. If it doesn't have a TSO authorization tag on it than there is no way to confirm it meets the requirements. Reading it in the sales literature won't work as far as the FAA is concerned. Repair stations are an extension of the FAA and operate under strict guidelines that hold them accountable to all applicable FAR's.

I think it *is* a moot point in the real world. I'm just curious what regulation requires the person doing the inspection of the transponder under 91.413 to determine and verify that the transponder complies with the TSO.

If the inspection requires the inspector to verify that the transponder is compliant with the TSO, then there should be a statement in the FAR which governs inspections. I don't see one there, but perhaps there is *another* FAR which does say this.

As I read 91.413 and the appendices, these are functional verification tests, not verifications of compliance to any TSO.

The only implied path that I can see to requiring verification of compliance to the TSO is if one or more of the test specified in the appendices cannot be done by the inspector, and can only be determined by checking that the manufacturer has done the test, presumably as part of their compliance to the TSO.

(I'm not trying to be argumentative here, but I deal with detailed requirements every day at work, and if something is not stated in a requirement, it's not required...period.)

 

[WhiskeyMike]

Doesn't say it has to actually be TSO'd, just that it meets the requirements of a TSO. The manufacturer (Dynon, for example) can say it meets the requirements, even if they haven't actually spent the hundreds of thousands of dollars to get an actual TSO.

Hard to imagine any manufacturer (Dynon, et al) making the claim that their equipment meets a given TSO's requirements if the product had not actually been thoroughly tested to the TSO standards. The liability associated with making this claim, and then subsequently having some element of the product fall short, could be financially catastrophic. Moreover, the manufacturer probably could not acquire the necessary product liability insurance for such a scenario. I think we're talking about the difference between business theory and business reality!

 

[IowaRV9Dreamer]

...what do we mean by the use of the pseudo-verb "TSO'd", as in "The GNS-430W is a TSO'd device"? Is that just a colloquialism? Or is there an actual piece of paper from the FAA or some other certifying body that is *required* to assert compliance with the TSO?

Oh yes there certainly is, and that piece of paper can take a LOT of work to get!

 

[Walt]

If the inspection requires the inspector to verify that the transponder is compliant with the TSO, then there should be a statement in the FAR which governs inspections. I don't see one there, but perhaps there is *another* FAR which does say this.

As I read 91.413 and the appendices, these are functional verification tests, not verifications of compliance to any TSO.

The only implied path that I can see to requiring verification of compliance to the TSO is if one or more of the test specified in the appendices cannot be done by the inspector, and can only be determined by checking that the manufacturer has done the test, presumably as part of their compliance to the TSO.

(I'm not trying to be argumentative here, but I deal with detailed requirements every day at work, and if something is not stated in a requirement, it's not required...period.)

Actually I agree with you, what the regs actually say and what the "intent" is can be totally different based on the inspector or FSDO's interpretation. Even most inspectors or FSDO's can't agree on the what the regs say and make up their own rules as they go along.

So even though technically speaking 91.215 applies to the operator and not the repair station performing the check, it is still considered the rule that requires a transponder to have a TSO and therefore repair stations are held accountable to that reg. Don't ask me why but thats the way it is

 

[RV6_flyer]

Here is what EAA has to say:

The following link is what EAA has to say about TSO equipment for IFR in Homebuilt aircraft. I have never found a lot of info from the FAA on what I call "GRAY AREAS".

http://members.eaa.org/home/homebuilders/faq/Equipping a Homebuilt for IFR operations.html#TopOfPage

You must be an EAA member to read the link. If you are building an aircraft, I am sure that you are already an EAA member.

My interpretation on what the FAA and EAA has to say is that you DO NOT have to have TSO'ed equipment but it is up to you to PROVE that your equipment meets the TSO. Your operating limitations reference 91.205 for NIGHT and IFR operations and no where in 91.205 does it say it has to be TSO'ed.

 

[Flying Scotsman]

Actually I agree with you, what the regs actually say and what the "intent" is can be totally different based on the inspector or FSDO's interpretation. Even most inspectors or FSDO's can't agree on the what the regs say and make up their own rules as they go along.

So even though technically speaking 91.215 applies to the operator and not the repair station performing the check, it is still considered the rule that requires a transponder to have a TSO and therefore repair stations are held accountable to that reg. Don't ask me why but thats the way it is

And here is where we part company. "What the regs actually say" is what the regs *actually are*. Otherwise, why have laws at all, if a bureaucrat can simply decide to make up new ones at will? And especially in this case, where the regulations are crystal clear as to what tests are required? Seems to be little wiggle room..."For all classes of ATCRBS transponders, interrogate the transponder and verify that the reply frequency is 1090±3 Megahertz (MHz)" and so on.

That doesn't seem very open to interpretation to me. And if someone at a FSDO says it is, in my mind, that's on par with the DAR who wanted the fuel caps painted red...that is, they're *making up rules as they go along*, and that's not what government in this country is supposed to be...

Similary, "technically speaking" 91.215 applies to operators and manufacturers means exactly that... it applies to operators and manufacturers, and *that's it*. There's nothing "technical" about it. It applies to those people, and not to inspectors, period.

We have rules and laws and formal processes in this country for a reason...to prevent arbitrary, willy-nilly application of them and the creation of new rules out of thin air based solely on some government employee's desires.

So I ask again...what regulation requires the person doing the bi-ennial transponder inspection to verify compliance with TSO C47c?

 

[Walt]

Part 145 Repair stations (the bi-ennial test) have their own set of Rules, that's the thing with the FAR's, you can keep going in circles till you find a rule that applies. There are other FAR's I could quote but this is one of them that they could hang the RS on if they blessed an "unairworthy" item....

§ 145.213 Inspection of maintenance, preventive maintenance, or alterations.

(a) A certificated repair station must inspect each article upon which it has performed maintenance, preventive maintenance, or alterations as described in paragraphs (b) and (c) of this section before approving that article for return to service.

(b) A certificated repair station must certify on an article's maintenance release that the article is airworthy with respect to the maintenance, preventive maintenance, or alterations performed after—

(1) The repair station performs work on the article; and

(2) An inspector inspects the article on which the repair station has performed work and determines it to be airworthy with respect to the work performed.

(c) For the purposes of paragraphs (a) and (b) of this section, an inspector must meet the requirements of §145.155

 

[SteinAir]

I'm not gonna get in the middle of this as far as interpretations go other than to say it appears everyone is in violent agreement to some extent.

That being said, there is still a big "gotcha" that sorta makes some of this a moot discussion. In order to get your transponder certified every 24 months it typically must be done by an FAA repair station. For most with a 145 certificate you'll find they must have your transponder on their "capabilities list", and in order for it to be put on the list, there are a host of requirements/specs which I as a CRS likely couldn't verify on your home made transponder....so no check on your unit. Like it or not, it's highly unlikely that most CRS's would even be able to legally & technically get a home brew Txpdr on to their list even if it did meet the specs (it is possible, just not probable).

Of course there are exceptions to the aforementioned statements, but for us homebuilders it's 99.9% applicable. Walt is right, you can run in circles on this topic with the FAA, and whether you agree or not that truly IS the case. Walt is spot on about the fact that the CRS regs are not the same as operator regs, and in many cases you end up with a complicated "daisy chain" of regs, advisories, bulletins, directives and so foth that end up chaising their own tails sometimes! You may read the regs and see them as crystal clear, but it just ain't so....as anyone with a repair station certificate will verify based on rel world experience. It may not be the way you think it's "supposed to be", but it's the way it actually is. I'm not sayin it's that way with every reg, but it is with some of them.

My 2 cents as usual!

Cheers,
Stein

 

[craigvince]

MODERATOR NOTE

This thread has gotten way off track. The original question was

What, if any, avionics has to be TSO for IFR cert. in my RV7?

The practical answer is, only the transponder.

No more discussion about the transponders. If you want to debate that, start another thread.