Thanks Dale & Mel, we have discussed the pro's and con's of converting his -12 to an E-AB (including the no going back clause), I have recommended against it, and he agrees. However, what I don't know are the rules surrounding modifying an E-LSA.
Can he install it himself and note it in the logbooks, same as an E-AB, or must an A&P do the install and document it? The owner is not the builder, not that it matters with an E-LSA.
The rules for E-AB and E-LSA are almost the same. Anyone can perform any maintenance, repair or alteration to the airplane, regardless of what certificate they do or do not hold. My dog Buddy could perform maintenance on my plane, if only he had opposable thumbs and knew how to read a torque wrench. I'm not 100% certain what log book entries are
required other than the condition inspection, but it's certainly a good idea to note the work in the log.
There are a couple of "quirks" to E-LSA. One is that anything that takes the airplane outside the limits of an LSA -- gross weight increase, in-flight adjustable prop, etc -- means you basically have a large airplane-shaped paperweight. It's no longer a legal LSA (and never can be again), and
there is no path to E-AB. It simply cannot be done. You can convert an
S-LSA to
E-LSA, but that's it.
The other quirk is that, unlike E-AB, an owner who did not build the airplane can obtain the repairman certificate with inspection privileges (LSR-I), which allows him or her to perform the condition inspection. That is the ONLY thing the LSR-I certificate does... allow you to do the CI on that specific airplane, listed by serial number. it's not required for anything else.
Hope that helps. I have a rather lengthy article about LSA certificates and rules that I keep threatening to finish and submit for publication, if I ever get the time.