It's due to a problem with FAA terminology, where they use the same phrase for a definition as the certification category.
If you look in
14CFR Part 1, you'll see "Light Sport Aircraft" defined:
Light-sport aircraft means an aircraft, other than a helicopter or powered-lift that, since its original certification, has continued to meet the following:
(1) A maximum takeoff weight of not more than—
(i) 1,320 pounds (600 kilograms) for aircraft not intended for operation on water; or
(ii) 1,430 pounds (650 kilograms) for an aircraft intended for operation on water.
(2) A maximum airspeed in level flight with maximum continuous power (V
H) of not more than 120 knots CAS under standard atmospheric conditions at sea level.
(3)...
The definition goes on with a total of thirteen defining characteristics of a Light Sport Airplane. This diagram sums it up:
Attachment 2047
What you won't see in there is ANYTHING related to certification, who can work on them, etc. That's because the "Light Sport Aircraft" is used to determine what a Sport Pilot is allowed to fly. ANY airplane, regardless of certification, meeting the Light Sport definition can be flown by a Sport Pilot.
At the same time, the FAA instituted two new certification classes in the Special category: Special Light Sport Aircraft (SLSA) and Experimental Light Sport Aircraft (ELSA). These aircraft meet the Part 1 LSA definition; in addition, they are designed and constructed in accordance with an Industry standard.
To gain certification as an Experimental Light Sport Aircraft, the manufacturer has to build an example of the airplane and prove that it complies with the requirements for Special Light Sport Aircraft. Once that is accomplished, the manufacturer can either sell the airplane ready-to-fly (Special Light Sport) or as a builder-assembled kit (Experimental Light Sport). The ELSA aircraft differ from the Experimental Amateur-Built category in that there is no "51%" rule. The seller of an ELSA kit can sell it at any level of completion.
The big difference is that the builder of an ELSA is not allowed to make any deviations in the construction of the aircraft... if the original manufacturer used a Rotax 912, the builder must also use a Rotax 912 of the identical model. If the kit manufacturer installed an ICOM A200 radio, the ELSA builder must ALSO install an ICOM A200... and not add anything, either.
Now, once the builder's ELSA is signed off by the FAA, that airplane is officially in the Experimental category, and the owner can make any changes they desire. But it must totally comply with the original aircraft at the time of certification.
OK, how does this affect the Zenith CH601HD?
The Zenith airplanes are Experimental Amateur-Built kits only. They meet the Part 1 definition of Light Sport Aircraft, hence they can be flown by Sport Pilots. However, they are licensed as Experimental Amateur-Built aircraft, and hence examples must comply with the "51% rule".
A ready-to-fly SLSA version of the CH601HD is sold by Aircraft Design and Manufacturing. As far as I know, an ELSA kit is not available. However, the owner of an SLSA can change it to the ELSA category if desired.
The best example of how it all works is the Vans RV-12. Vans designed the RV-12 in accordance with the rules for SLSA, got one example approved, and now sells ELSA RV-12 kits. However, Vans *also* got the RV-12 kits approved under the 51% rule for Experimental Amateur-Built. If you buy an RV-12 kit, you can build it EITHER as ELSA or EX-AB.
The difference?
If ELSA, you cannot deviate from the construction manual for any reason. Once you get an airworthiness certificate, you can then make changes. You can do all the maintenance yourself, and can attend a 16-hour course that allows you to perform the annual inspections on any ELSA that you own. If you sell the RV-12, the new owner can take the same course and will then be approved to perform annuals on the aircraft he purchased. Or, anyone can hire an A&P or a person holding a Light Sport Maintenance rating to do the annual.
If you build it as Experimental Amateur-Built, you can deviate from the plans all you want, and, like the ELSA, you can do all the maintenance yourself once completed. As the builder, you can apply for a Repairman Certificate that permits you to perform the annual condition inspection *on that aircraft alone*. If you sell the completed aircraft, the new owner cannot receive a Repairman Certificate...he or she must either have you do the annuals, or hire an A&P to do them.
Ron Wanttaja