Question on non-TSO'd instruments for Mr. Lyons

[cliffy]

All your previous posts referenced Part 23 certified aircraft. What might be the situation with CAR3 certified Mooneys as many of the older ones come under that cert?  

[peter]

Are we still talking about EFIS? 

CAR 3 or part 23 aside, it is part 21 that requires changes to a certified aircraft to be approved.  The original certification basis (CAR3, FAR23, etc.) establishes the rules against which changes are evaluated for approval, but don't change the need to obtain an approval for the change.

The rules have become more stringent over time, so having a CAR3 basis can make getting an approval "easier."  However, for newer technology (like EFIS) where the original rules may not be adequate, the FAA can and does apply later rules and issues special conditions. In the case of the Aspen EFIS, the latest FAR ammendment was applied as the cert basis, even for aircraft originally approved under CAR3.  The FAA also applied special conditions for HIRF, and required we meet the latest requirements for direct effects of lightning. 

So, even for aircraft that are originally approved under CAR 3, the FAA can require that later rules be applied when an aircraft is being modified.  For the owner operater working with their A&P or seeking a field approval this probably won't come up as much as it might for a manufacturer seeking an STC for new technologies or equipment.