In order to replace an Airspeed Indicator, Altimeter or other Primary Flight instruments; the instrument must be approved.
One way to be approved is that it meets the relevant TSOs.

So, an Air Speed indicator from any manufacturer (given appropriate face markings) is appropriate if it has a TSO?


Q: Is there any additional requirements for it to be installed?
- Is an STC or Field Approval required if the gauge is a different brand? (Swapping an original Kohlsman Scout Altimeter for a new United TSO'd Altimeter, for example)
- Is there a requirement for the gauge to be 3 1/8" inch? If I found a 2 1/4" TSO'd altimeter, for example.
- Is there a requirement that each instrument be it's own separate device? If I found a 2 in 1 Altimeter/VSI TSO'd gauge, for example.

I can't find any definitive data.

What was your plane certified under? CAR 4???

CAR 3 but it's not relevant to the question.

By itself, a TSO is not an installation approval. See FAA AC 21-50 - Installation of TSOA Articles and LODA Appliances, specifically paragraph 4.a. : https://www.faa.gov/documentLibrary/media/Advisory_Circular/AC_21-50.pdf

Additional guidance is available in FAA AC 23-27, PARTS AND MATERIALS SUBSTITUTION FOR VINTAGE AIRCRAFT:
https://www.faa.gov/documentLibrary/media/Advisory_Circular/AC_23-27.pdf

If the aircraft in question was type-certificated after 01 Jan 1980, then FAA AC 20-62E, Eligibility, Quality, and Identification
of Aeronautical Replacement Parts, is more pertinent:
https://www.faa.gov/documentLibrary/media/Advisory_Circular/AC%2020-62E.pdf

pat

I think the following Advisory Circular would be relevant to what it sounds like you are doing. It is ancient but still valid. We use it for many cases for replacing ancient TSO'd boat anchors with more modern TSO'd equivalents.

https://www.faa.gov/documentLibrary/med ... 20-41A.pdf

Thanks.
All of those links are helpful.

A TSO in itself does not approve an instrument for installation - makes sense.
AC 21-50 4.a states that along with the TSO, you need to show the device to satisfy other relevant airworthiness requirements.
I'm guessing the relevant airworthiness requirements would be listed in the regulations the aircraft was certified under? In my case, CAR3?

So along with meeting minimum requirements (being TSOd) it need to also comply with CAR3?

AC 21-50 4.b.2 wrote:To the extent that the FAA-approved TSOA data aligns with the applicable airworthiness
requirements, the data needs no further substantiation or evaluation by the FAA.

So if the the TSO documentation for a device shows it complies with CAR3 requirements - it's approved for installation (No further substantiation or evaluation by the FAA).


AC 20-41A 6 . Specifically excludes AutoPilots and other things including wheels and tires... and says

AC 20-41A 6 wrote:Substitutions which affect equipment in the cockpit should be evaluated by appropriate flight test personnel.

What/who are appropriate flight test personnel?

What sent me down this path is the Sandia SAI 340 which carries the Altimeter, Airspeed, Artificial Horizon, and a few other TSOs.

If the device is TSOd for those functions and satisfies CAR3 requirements for airworthiness - Why can I not install is as my primary flight instruments?

I can't find where it says it can't but everyone I talk to says it can't be done.

Another example is the Aspen Evolution. They have a landscape version that is TSOd the same as their portrait versions but the landscape version is marketed as a Backup. When I asked Aspen, they told me there is no difference in the two except for the orientation.

The Garmin G1000 carries the same TSOs for Airspeed, Altimeter and other primary instruments as the Sandia SAI 340 (from what I can tell).
What makes one primary and one not primary?

Ah ha - you desire to install an Electronic Display in a CAR 3 airplane!

Recommend navigating to:
http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgPolicy.nsf/0/6a24902ae5f1aeac86257ec1005b2fbc/$FILE/PS-ACE-23-08.pdf

pat

iPat wrote:Ah ha - you desire to install an Electronic Display in a CAR 3 airplane!

Recommend navigating to:
http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgPolicy.nsf/0/6a24902ae5f1aeac86257ec1005b2fbc/$FILE/PS-ACE-23-08.pdf

pat

Pat, this only covers vac driven instruments doesn't it? Doesn't cover airspeed and altimeter does it?
I've wo dared the same Bagarre. Why can't my G5 act as an airspeed and altimeter as well? Its all there any ways...

A1Skinner wrote:

iPat wrote:Ah ha - you desire to install an Electronic Display in a CAR 3 airplane!

Recommend navigating to:
http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgPolicy.nsf/0/6a24902ae5f1aeac86257ec1005b2fbc/$FILE/PS-ACE-23-08.pdf

pat

Pat, this only covers vac driven instruments doesn't it? Doesn't cover airspeed and altimeter does it?
I've wo dared the same Bagarre. Why can't my G5 act as an airspeed and altimeter as well? Its all there any ways...

I see the G5 as a different animal as it carries no TSOs and as such does not have data to show it complies with minimum standards ...Other than a flawless track record in tons of EAB aircraft.

But I just came across this
http://fsims.faa.gov/Wdocs/Other/Major_ ... d%20R5.pdf

It makes the distinction between Electronic flight instrument systems (EFIS) and Electronic horizontal-situation indicators (EHSI)
With the former requiring an STC (D.13k) and latter an Evaluation (D.13l).

So by default an EFIS requires an STC unless you can convince your FSDO otherwise. Heh, that pretty much sums up everything in aviation these days.

Interestingly it states at D.13h(1) Simple Two Access Autopilots do not require STC but can be field approved via Engineering data

Pretty sure the G5 has a TSO. Or maybe it's just STCd fo certified A/C. It has to have one or the other or wouldn't be allowed as a replacement for certified A/C would it?

The G5 is non-TSO'd but can be installed as an artificial horizon or DG via their STC.
That was the big deal about the G5 and Dynon's D10 - Non TSO'd equipment installed via STC....but only for EHSI not EFIS.

Bagarre wrote:The G5 is non-TSO'd but can be installed as an artificial horizon or DG via their STC.
That was the big deal about the G5 and Dynon's D10 - Non TSO'd equipment installed via STC....but only for EHSI not EFIS.

Ok. Gotcha. Thanks for straightening that out.

Garmin's G5 for Certificated airplanes http://static.garmin.com/pumac/SA01818WI_1710.pdf required significant resources to obtain the STC (have a read of the references), especially without a TSO.

Altho it does meet multiple TSOs, I cannot find an STC for Sandia's SAI 340 Quattro. Therefore, the installer must obtain installation approval, and this is alluded to on Sandia's website of FAQs for the Quattro. One avenue would be to replace the attitude indicator, but doing so "may" require disabling the Quattro's airspeed and altimeter functions in order to meet the FAA's policy of "A single function vacuum-driven attitude indicator may also be replaced with an electronically-driven attitude indicator that provides a secondary (advisory) function (such as turn & slip indication)." Ref page 3 of PS-ACE-23-08.

I have seen the Quattro and think it has an excellent display, and I also think referencing a full-featured Quattro is easier (read: reduced pilot workload) than cross-referencing multiple analog gages. That said, I do not see an easy avenue of compliance. One could ask FAA to revise the Policy Statement....

-pat