Several of the folks I do owner-assisted annuals for have asked me how to get them to ADS-B Out status. One of them has taken the bull by the horns and installed an Appareo unit under my supervision. The question is whether to do a logbook entry or a 337. My lean right now is to do the installation on a logbook entry. The installation itself is something I'd let a level 1 novice A&P or avionics technician handle. It is rather trivial, is also the testing/checkout. The actual final cert and such is going to be handled by an avionics shop with all the good test gear and such that this sort of installation requires, so the actual installation and preliminary testing is all that I have to worry about. The Appareo unit itself (along with its requisite transponder, encoder, and antennas) are all TSO'd and the unit is being installed in accordance with the FAA's new stroke of genius allowing a single STC on a part 23 aircraft serve as a "lead STC" for similarly certificated aircraft. (See http://www.appareo.com/faa-rebate-stc-aml/ for a discussion of this concept.) FAA (Western Region) came out with a document a few years ago discussing the difference between a minor (logbook) modification and a major (337) modification. The examples used were a major engine type change (IO360 in place of an O-200) and a minor radio installation. Anything in between, according to them, was whether the INSTALLING MECHANIC considered the change major or minor. That, of course, lets the FAA challenge the wisdom of the mechanic any time they see fit. I'd like to hear from those of you who have actually done ADS work your reasoning and results doing either logbook or 337. Thanks, Jim .