Training

March 2019 Issue




TSO Certifications:Here To Stay, For Now

Straightforward and costly, product certification via FAA TSO remains an international standard. But broad STC approvals are lowering costs.

Digging deeply into the installation data for Garmin's new GTR200B comm radio got us thinking about the requirement of TSO certification. With autopilots and primary EFIS systems being approved without a TSO, but instead via AML-STC (approved model list supplemental type certificate), are the days of TSO approval coming to an end? Garmin-a company that cranks out a lot of them in short order-says no. You don't have to dive far into the regulations to see why.

The GTR200B, like most Garmin avionics aimed at the LSA and experimental market, doesn't have a TSO and it doesn't have an STC, pretty much killing it for Part 23 certified aircraft. And yes, a retrofit comm radio requires some form of certification. The TSO process remains the most common way to get there. It's a vigorous and expensive approval process that can drag along.

As an example, TKM Avionics in Scottsdale, Arizona, is long-delayed releasing its MX155 next-gen digital replacement radio as it keeps feeding R&D cash to the TSO process. The TKM name is no stranger to the industry; the original company built certified VHF radios as early as the 1980s.

We asked Garmin for a lesson in product certification as it relates to the TSO, and it led us to a slew of regulatory jargon that's worth sharing. Garmin's Bill Stone pointed out some pretty specific wording in the regulations, reiterating that as a replacement or modification article (no matter how basic its functions are) the product's design does need to be FAA approved. Additionally, the manufacturer of the article has to be a holder of an FAA production approval. The TSOA (technical standard order authorization) is still the most accepted means for doing so.

It's ALL In The Regs

For starters, 14 CFR 21.8, which covers the approval of articles, states that if an article is required to be approved under this chapter, it may be approved with a PMA (parts manufacturing approval), under a TSO, in conjunction with type certificate procedures for a product or in any other manner approved by the FAA.

The FAA's 14 CFR 21.9 deals with replacement and modification articles and has pretty specific language even when it comes to production. It says, in part, that if a person knows, or should know, that a replacement or modification article is likely to be installed on a type-certificated aircraft (maybe it's a Piper Arrow, as one of many plain-vanilla examples), the person may not produce that article unless it is produced under a type certificate or under an FAA production approval.

Garmin pointed out that the rules in CFR 21.9 pretty much answer our question of why the non-TSO'd GTR200B radio is off-limits to Part 23 certified aircraft. To comply with this regulation, Garmin has to state that the product is not suitable for installation in a type-certified aircraft. It's not just about U.S. regulations, either.

The TSO is an internationally recognized approval basis, so it allows for export and installation of the product in aircraft under the jurisdiction of civil aviation authorities other than the FAA. And the regs aren't all about aircraft.

Since a VHF comm radio contains a transmitter, there needs to be a method for what's called Spectrum Agency approval. In the United States, that's the FCC.

Garmin said that a TSO provides a pedigree for bilateral acceptance of the FAA/FCC Spectrum approval in most countries around the world. Lacking a TSO, a manufacturer would have to submit for Spectrum approval for a VHF transmitter in every country it intended to sell the product, in addition to every country where the product may get used.

A Mix of TSO and STC Approvals

A few years ago Dynon Avionics and EAA (Experimental Aircraft Association) started the industry-changing trend of sidestepping the TSO process in favor of a broad AML-STC with the D10A primary EFIS. Since then, we've seen several major products (including EFIS and autopilots from Garmin, Aspen and TruTrak) approved for certification in type-certified aircraft despite not having a TSO. While we think that trend will continue, don't expect the TSO to go away any time soon.