I know it's still early with the FAA’s Modernization of Special Airworthiness Certification (MOSAIC) Notice of Proposed Rulemaking, but as it is currently written (August 2023), could I operate my Cessna 172 as a LSA, and install, as an example, the experimental version of the Garmin G5 ~$1,800 rather than the certificated version ~$2,800, and save myself thousands of dollars?

AOPA's reporting on it makes it seem so:

Among those likely to be enthusiastic about the proposed changes are owners of existing aircraft that could soon qualify as LSAs, and experimental avionics firms that can sell their products much more broadly.

  • $\begingroup$ There is no such thing as "experimental" avionics, and very few avionics need any for of certification at all for Part 91 activities. You may install any avionics you wish, so long as the plane's airworthiness is maintained. The broadest way to do that is to get A&P sign-off. However, there are other routes as well. Certified Type Normal gliders all over the US have glide computers, not a one of which AFAIK is certified. $\endgroup$ Commented Aug 23, 2023 at 17:28
  • $\begingroup$ @KennSebesta A big benefit of installing a G5 is removing the vacuum system. I believe the 172's POH lists its vacuum system as required equipment and so needs an STC to remove, which the "certified" G5 provides and the "experimental" G5 does not. No idea if MOSAIC changes any of this or not. $\endgroup$
    – Chris
    Commented Aug 24, 2023 at 7:23
  • $\begingroup$ Also if I recall correctly the experimental G5 has some small differences (e.g. the AI can be switched in flight into an HSI and vice-versa) and is not TSO'd. Which I believe would make it illegal for use in IFR flight? $\endgroup$
    – Chris
    Commented Aug 24, 2023 at 7:29
  • 1
    $\begingroup$ Based on your approximate costs, it looks like a savings of thousand (singular) dollars, not thousands (plural) dollars. $\endgroup$
    – FreeMan
    Commented Aug 24, 2023 at 15:05
  • $\begingroup$ @Chris those are excellent points. It comes down to the motivations for someone to install a G5, and judging from what you say the benefits are definitely there for getting the STC'ed version. $\endgroup$ Commented Aug 24, 2023 at 21:24

2 Answers 2


The short answer is a qualified "maybe."

The heart of MOSAIC is that they're not going to base a 'yes a sport pilot can fly it' rule on aircraft type or equipment package. They're going to base it on VS1 being 54 KCAS or less (which not all 172s can achieve, so check your specific POH), that it has positive control at virtually all times, and that its controls are characterized as 'simple' or easy to manage (which your experimental Garmin may or may not).

Keep in mind that installing avionics that invalidates it as a non-MOSAIC 172 may mean you (or other operators) lose privileges like the use of seats 3 and 4, or IFR operations, which could also impact resale value. Make sure you've done your homework and know what the STC could cost before you decide that you're actually saving thousands of dollars.

  • $\begingroup$ +1. This is a great answer. Cost considerations must include the rules you must abide by, if installed, as the answer states. $\endgroup$
    – wbeard52
    Commented Jan 21 at 21:33

No. Under the proposed rulemaking, a sport pilot may act as pilot in command of an aircraft that fits the restrictions (54 KCAS, etc.), but your 172 will still have a standard airworthiness certificate. Per the proposed § 21.181(a)(1):

Standard airworthiness certificates and special airworthiness certificates issued for aircraft certificated in the primary, restricted, or limited category are effective as long as the maintenance, preventive maintenance, and alterations are performed in accordance with parts 43 and 91 of this chapter.

you are still required to perform maintenance in accordance with parts 43 and 91 to keep your airworthiness certificate valid. Per the proposed § 21.190, you can apply for a special airworthiness certificate in the light-sport category if your aircraft meets the requirements of § 22.100. Unfortunately, the 172 does not comply with § 22.100(a)(6):

(6) Not have been previously issued a standard, primary, restricted, limited, or provisional airworthiness certificate, or an equivalent airworthiness certificate by a foreign civil aviation authority.

and so it is not possible to get a special airworthiness certificate in the light-sport category for a 172.

In short, under the proposed rulemaking, a sport pilot can act as PIC in some non-light-sport aircraft, but this does not make them light-sport aircraft.


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