E-LSA vs E-AB
Why this matters before you build
The RV-15 can be certificated down either of two paths, and the choice constrains how you are allowed to build. Deciding late is expensive: work already done to your own preference can close the E-LSA door behind you.
- E-LSA — Experimental Light-Sport, kit-built, certificated under 14 CFR 21.191(k). You build the kit to the manufacturer's instructions. There is no 51% requirement and no percentage to calculate — but deviations are what disqualify you.
- E-AB — Experimental/Amateur-Built, certificated under 14 CFR 21.191(g). You may build and modify as you see fit, but you must show that the major portion (more than 50%) of fabrication and assembly was done by amateur builders for education or recreation. See NKET Checklist.
What Van's has said
At the Van's engineering forum at Oshkosh 2026, Rian Johnson and Brian Hickman stated that Van's expects most builder-completed RV-15s to be certificated E-LSA, and that Van's does not intend to seek FAA National Kit Evaluation Team (NKET) listing for the 51% rule. Anyone going E-AB completes their own checklist. Source
Brian Hickman subsequently clarified that Van's Engineering is developing a list of accepted alterations that will not disqualify a build from E-LSA, and that recessed/flush solid rivets on the leading edges will be on that list; alternate brake systems likely will be too. Until the list is published this is verbal guidance only. Source
The two paths compared
| E-LSA (21.191(k)) | E-AB (21.191(g)) | |
|---|---|---|
| Who is the "manufacturer" | Van's | You, the amateur builder |
| Build standard | Assembled per the manufacturer's assembly instructions, which must meet an FAA-accepted consensus standard | Your choice — modify freely |
| Percentage requirement | None | Major portion (>50%) by amateur builders |
| Paperwork from the kit maker | Manufacturer's Statement of Compliance, FAA Form 8130-15, issued for the kit | None required; a manufacturer's NKET checklist helps if the kit is listed — the RV-15 is not |
| Paperwork from you | Application for airworthiness certificate | Fabrication and Assembly Checklist plus builder log, photos and records showing who did what, when and where |
| Deviations during the build | Disqualifying unless on Van's accepted-alterations list | Unrestricted |
| Operating privileges | Same as E-AB — no restriction on use | No restriction on use |
| Condition inspection | Repairman (light-sport) inspection certificate, or an A&P | Repairman (experimental) certificate for the primary builder, or an A&P — and since MOSAIC, an owner holding a Repairman (light-sport) inspection certificate may also perform it |
What MOSAIC changed, and when
The FAA's MOSAIC final rule published 24 July 2025. The pilot-privilege and maintenance provisions took effect in October 2025; the light-sport aircraft certification provisions took effect 24 July 2026.
- Kit-built light-sport is now certificated under 14 CFR 21.191(k). Original issuance under the older 21.191(i)(2) ended 22 October 2025; aircraft originally certificated under (i)(2) get replacement certificates issued under (k). FAA MOSAIC FAQ
- LSA are no longer defined by a weight limit. The definition is performance-based (stall speed), and light-sport category aircraft may now have up to four seats, retractable gear and constant-speed propellers.
- New LSA and new LSA kits delivered on or after 24 July 2026 must comply with the new consensus standards under 14 CFR part 22. The standards in effect on the date the manufacturer signed the Statement of Compliance for your kit are the ones that apply to your aircraft.
- The FAA does not issue design or production approvals for LSA. Compliance rests on the manufacturer's statement of compliance against FAA-accepted consensus standards.
- Any owner of an Experimental/Amateur-Built aircraft may now take the 16-hour LSA repairman inspection course and perform their own annual condition inspection — a privilege that previously required being the primary builder.
Open questions
These are unresolved as of August 2026 and should be confirmed before making an irreversible build decision:
- Has Van's issued a Statement of Compliance (FAA Form 8130-15) for the RV-15 kit? E-LSA under 21.191(k) depends on it. Van's stated intent at OSH is clear, but intent is not a signed SOC.
- The accepted-alterations list has not been published. Flush leading-edge rivets are stated to be on it; nothing else is confirmed in writing.
- Avionics. Builder-selected avionics may force E-AB, because the POH and maintenance documentation depend on what is installed. Discussion
- Builder-installed aftermarket brakes and similar equipment: the practical advice offered on the forum is that if you intend to go E-LSA, leave such parts in the box until after the airworthiness certificate is issued.
Practical notes from builders
- Builders who have completed the E-AB checklist for other aircraft describe it as an hour or two of work, not an obstacle. Source
- Two RV-15 builders with completed wings and tails scored themselves against the FAA form and found the major-portion case straightforward. Source
- Filling pulled-rivet holes for cosmetics is not by itself a build deviation — one DAR characterises it as ordinary paint preparation. Source
Sources
- FAA — MOSAIC rule page
- FAA — MOSAIC FAQ: Manufacture and Certification of Light-Sport Category Aircraft
- AC 20-27G, Certification and Operation of Amateur-Built Aircraft
- VAF — Louise Hose's report on Van's engineering forum, OSH 2026
This page summarises regulations that are changing quickly and is maintained by builders, not by the FAA or Van's. Confirm anything that affects your build with your FSDO, MIDO, DAR or the FAA directly before acting on it.