Aircraft Certification

Register and certify your homebuilt aircraft project

FAA Airworthiness Certification & Registration Information and Resources for Sonex Aircraft

Sonex Aircraft, LLC has partnered with the FAA, EAA and other aircraft manufacturers to play a leading role in shaping and adopting today's Experimental/Amateur-Built aircraft rules. We have compiled this page of information to help Sonex Aircraft builders register and certify their homebuilt aircraft projects.

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"Major Portion" or "51 Percent Rule" Compliance

FAA_NKET_8137_250.jpgOn March 31 2010, Sonex Aircraft, LLC kits became the first amateur-built kits to be accepted by the FAA under Advisory Circular AC 20-27G, FAA Order 8130.2, and FAA Order 8130.35B via FAA National Kit Evaluation Team (NKET) evaluation, with all new aircraft models and kit variations being audited and accepted since that time. Sonex Aircraft recommends that all builders thoroughly read and understand these rules. All Sonex Aircraft kits can be found on the FAA's listing of Amateur-Built Kits Checklists and Approval Letters Evaluated by National Kit Evaluation Team (NKET) with direct links below to help builders easily identify the proper checklist to use for their specific kit.

NKET evaluation not only bolsters the pre-existing, grandfathered evaluations of Sonex Aircraft kits, but it also updates the acceptance to include the latest Pre-Assembled Main Wing Spar and Machined Angle Component, Matched-Hole Formed Parts, and Quick Build kit upgrades offered by Sonex Aircraft, LLC, showing that all Sonex Aircraft kits with all available options can be built within the rules. Additionally, Sonex Aircraft customers can use NKET checklists to determine exactly how much commercial assistance may be used in the construction of their projects without violating the "major portion" requirement of 14 CFR section 21.191(g) for experimental/amateur-built aircraft, commonly referred to as the "51 Percent Rule."

Sonex Aircraft builders should download the appropriate selection among the following Amateur-Built Aircraft Fabrication and Assembly Checklist forms for Sonex aircraft, for use as kit compliance documents. Instructions for using these checklists can be found in FAA Advisory Circular AC 20-27G.

FAA NKET Amateur-Built Fabrication and Assembly Checklists:
SubSonex:
Quick Build Kit:
Sonex-B:
Quick Build Kit:
Complete Airframe Kit or Sub-Kits:
  • Sonex-B (Sonex B-Model Kit Checklist for use with Complete Airframe Kit or Sub-Kits)
  • Eligibility Letter (Sonex-B, Waiex-B & Xenos QuickBuild Kit Letter of Eligibility)
Sonex:
Quick Build Kit:
  • SONEX_SNX-QB-070813.pdf (Sonex Kit Checklist for use with Sonex Quick Build Kit)
  • Sonex_0726201311293100.pdf (Sonex/Waiex/Onex Kit Letter of Eligibility for use with Pre-Assembled Main Wing Spar and/or Machined Angle Component Kit upgrades + Matched-Hole Formed Parts added to kits August, 2012 or Quick Build Kits)
Complete Airframe Kit or Sub-Kits (shipped August, 2012 or later -- includes Matched-Hole Formed Parts):
  • SONEX_SNX-KIT-ALL-MHP-070813.pdf (Sonex Kit Checklist for use with or without Pre-Assembled Main Wing Spar and/or Machined Angle Component Kit upgrades: any kit shipped August, 2012 or later -- includes Matched-Hole Formed Parts)
  • Sonex_0726201311293100.pdf (Sonex/Waiex/Onex Kit Letter of Eligibility for use with Pre-Assembled Main Wing Spar and/or Machined Angle Component Kit upgrades + Matched-Hole Formed Parts added to kits August, 2012 or Quick Build Kits)
Complete Airframe Kit or Sub-Kits (shipped prior-to August, 2012) with Pre-Assembled Main Wing Spar and/or Machined Angle Component kit upgrades:
  • SonexFinishSpar.pdf (Sonex Kit Checklist for use with Pre-Assembled Main Wing Spar and/or Machined Angle Component Kit upgrades)
  • SonexFinishSparLtr.pdf (Sonex Kit Letter of Eligibility for use with Pre-Assembled Main Wing Spar and/or Machined Angle Component Kit upgrades)
Complete Airframe Kit or Sub-Kits (shipped prior-to August, 2012) with no kit upgrades:
  • Sonex.pdf (Sonex Kit Checklist for use without Pre-Assembled Main Wing Spar and/or Machined Angle Component Kit upgrades)
  • SonexLtr.pdf (Sonex Kit Letter of Eligibility for use without Pre-Assembled Main Wing Spar and/or Machined Angle Component Kit upgrades)
Waiex-B:
Quick Build Kit:
Complete Airframe Kit or Sub-Kits:
  • Waiex-B (Waiex B-Model Kit Checklist for use with Complete Airframe Kit or Sub-Kits)
  • Eligibility Letter (Sonex-B, Waiex-B & Xenos QuickBuild Kit Letter of Eligibility)
Waiex:
Quick Build Kit:
  • WAIEX_WIX-QB-070813.pdf (Waiex Kit Checklist for use with Waiex Quick Build Kit)
  • Sonex_0726201311293100.pdf (Sonex/Waiex/Onex Kit Letter of Eligibility for use with Pre-Assembled Main Wing Spar and/or Machined Angle Component Kit upgrades + Matched-Hole Formed Parts added to kits August, 2012 or Quick Build Kits)
Complete Airframe Kit or Sub-Kits (shipped August, 2012 or later -- includes Matched-Hole Formed Parts):
  • WAIEX_WIX-KIT-ALL-MHP-070813.pdf (Waiex Kit Checklist for use with or without Pre-Assembled Main Wing Spar and/or Machined Angle Component Kit upgrades: any kit shipped August, 2012 or later -- includes Matched-Hole Formed Parts)
  • Sonex_0726201311293100.pdf (Sonex/Waiex/Onex Kit Letter of Eligibility for use with or without Pre-Assembled Main Wing Spar and/or Machined Angle Component Kit upgrades + Matched-Hole Formed Parts added to kits August, 2012 or Quick Build Kits)
Complete Airframe Kit or Sub-Kits (shipped prior-to August, 2012) with Pre-Assembled Main Wing Spar and/or Machined Angle Component kit upgrades:
  • WaiexFinishSpar.pdf (Waiex Kit Checklist for use with Pre-Assembled Main Wing Spar and/or Machined Angle Component Kit upgrades)
  • WaiexFinishSparLtr.pdf (Waiex Kit Letter of Eligibility for use with Pre-Assembled Main Wing Spar and/or Machined Angle Component Kit upgrades)
Complete Airframe Kit or Sub-Kits (shipped prior-to August, 2012) with no kit upgrades:
  • Waiex.pdf (Waiex Kit Checklist for use without Pre-Assembled Main Wing Spar and/or Machined Angle Component Kit upgrades)
  • WaiexLtr.pdf (Waiex Kit Letter of Eligibility for use without Pre-Assembled Main Wing Spar and/or Machined Angle Component Kit upgrades)
Onex:
Quick Build Kit:
  • ONEX_ONX-QB-070813.pdf (Onex Kit Checklist for use with Sonex Quick Build Kit)
  • Sonex_0726201311293100.pdf (Sonex/Waiex/Onex Kit Letter of Eligibility for use with Pre-Assembled Main Wing Spar and/or Machined Angle Component Kit upgrades [all Onex kits shipped since 2011 include Matched-Hole Formed Parts] or Quick Build Kits)
Complete Airframe Kit or Sub-Kits with Pre-Assembled Main Wing Spar and/or Machined Angle Component kit upgrades:
  • ONEX_ONX-KIT-ALL-MHP-070813.pdf (Onex Kit Checklist for use with Pre-Assembled Main Wing Spar and/or Machined Angle Component Kit upgrades)
  • Sonex_0726201311293100.pdf (Sonex/Waiex/Onex Kit Letter of Eligibility for use with Pre-Assembled Main Wing Spar and/or Machined Angle Component Kit upgrades [all Onex kits shipped since 2011 include Matched-Hole Formed Parts] or Quick Build Kits)
Complete Airframe Kit or Sub-Kits with no kit upgrades:
  • Onex.pdf (Onex Kit Checklist and Letter of Eligibility for use without Pre-Assembled Main Wing Spar and/or Machined Angle Component Kit upgrades)
  • OnexLtr.pdf (Onex Kit Letter of Eligibility for use without Pre-Assembled Main Wing Spar and/or Machined Angle Component Kit upgrades)
Xenos:
Quick Build Kit:
Complete Airframe Kit or Sub-Kits with Pre-Assembled Main Wing Spar and/or Machined Angle Component kit upgrades:
  • XenosFinishSpar.pdf (Xenos Kit Checklist for use with Pre-Assembled Main Wing Spar and/or Machined Angle Component Kit upgrades)
  • XenosFinishSparLtr.pdf (Xenos Kit Letter of Eligibility for use with Pre-Assembled Main Wing Spar and/or Machined Angle Component Kit upgrades)
Complete Airframe Kit or Sub-Kits with no kit upgrades:
  • Xenos.pdf (Xenos Kit Checklist for use without Pre-Assembled Main Wing Spar and/or Machined Angle Component Kit upgrades)
  • XenosLtr.pdf (Xenos Kit Letter of Eligibility for use without Pre-Assembled Main Wing Spar and/or Machined Angle Component Kit upgrades)

Amateur-Built Aircraft Fabrication and Assembly Checklist form FAQ's:

Q: What is so significant about these checklists? A: The Sonex, Waiex, and Xenos were the first Amateur-Built Kits to be accepted by the FAA under Advisory Circular AC 20-27G, FAA Order 8130.2, and FAA Order 8130.35, with all new aircraft models and kit variations being audited and accepted since that time. Sonex encourages everyone involved with Experimental-Amateur Built Aircraft to thoroughly read and understand these rules.

Q: I'm building a Sonex Aircraft, how do I use this checklist? A: These new checklists are the starting point for you if you purchase a Sonex Aircraft Complete Airframe Kit, Sub-Kits or Quick Build Kits. You should use these checklists to prove that you are building the majority of the aircraft. You can also use these new lists to legally obtain commercial assistance on your project. The column on the right-hand side contains a place for the FAA (or FAA Designated) Inspector to review what you've had done for you to ensure compliance as part of your aircraft registration process. If considering commercial assistance with your project you can pre-fill a sample checklist to run the calculations and check for compliance.

Q: How do I get a copy of the checklists? A: Download them right from our web site (above)! We have established this web page dedicated to materials needed for registration.

Q: I have a lot of questions on how to register my homebuilt aircraft. What should I do? A: Order the comprehensive Amateur-Built Aircraft Certification Kit (below) from EAA. This should answer all of your questions by providing a step-by-step guide through the registration process.

Recommended Reading: EAA Experimenter Magazine, January 2013 "Building Your Homebuilt Using the New FAA Major Portion Checklist" by Joe Gauthier

Still Have Questions?: Contact Sonex Aircraft


Registration and Airworthiness Certification

EAA_cert_kitSonex Aircraft, LLC highly recommends that all builders use the EAA Amateur-Built Aircraft Certification Kit, which is available for purchase online.

The kit includes everything you need to register and certificate a new experimental amateur-built aircraft. The 15-page, step-by-step Certification Guide walks you through the entire process-from getting an N number to the aircraft inspection-and provides samples of how to complete each required form. The certification kit also includes all FAA forms, Experimental sticker (in black), dataplate, and a convenient placard decal sheet.


Xenos Motorglider Certification Tips

Updated: 09/03/2020

We asked Joe Norris of EAA, one of the foremost experts on Experimental Aircraft Registration, and he responded with the following:

The current state of FAA guidance on certification of experimental aircraft makes it especially difficult to get an aircraft certificated as a powered glider. Previous guidance on the subject was removed during recent revisions of FAA documents, so there is no clear path to powered glider certification. EAA is working with FAA to restore the previous guidance, but I have no timeline for such a reversal of policy, nor can I guarantee that it will occur.

This being the case, it would be far easier to certificate your aircraft as an experimental amateur-built airplane. The path to amateur-built airplane certification is clear and well known, so there would be no issues. If you were to choose to pursue powered glider certification, I can just about guarantee that you will end up having to try to educate the FAA inspector or DAR who performs the inspection, and I can't guarantee a favorable outcome.

Of course, there's no regulation that prohibits occasionally shutting off the engine and doing some soaring, even though the aircraft is an "airplane"!

Sonex Aircraft, LLC also recommends that you fill out your 8050-88 form to read Model: Xenos Motorglider.


Definition of Motorglider or Powered Sailplane

Sonex Aircraft, LLC accepts the formal definition of Powered Sailplanes for Type Certificated Aircraft from both the United States and the European Aviation Authorities. While it is not formally defined that an Aircraft Registered in the Experimental Category must meet these same criteria, any aircraft which does meet the criteria is an indisputable "Motorglider" or "Powered Sailplane." The language in both the U.S. and the European documents are nearly identical and the portion of the documents which apply to this definition as follows:

 

United States Department of Transportation, Federal Aviation Administration
Advisory Circular AC 21-17a, dated 10 February 1993

7. ACCEPTABLE CRITERIA.
  b. Additional Criteria for Powered Gliders.
    (1) Powered fixed wing gliders may be type certificated under Section 21.17(b) if:
      (i) The number of occupants does not exceed two;
      (ii) Maximum weight does not exceed 850 kg (1874 pounds); and
      (iii) The maximum weight to wing span squared (w/b2) does not exceed 3.0 kg/M2 (0.62 lb./ft.2).
NOTE: These criteria originated from JAR-22.

Joint Aviation Authorities
JAR-22 Amendment 7, dated 1 September 2003

JAR 22.1 Applicability
(a) This JAR-22 prescribes minimum airworthiness standards for the issue of type certificates, and changes to those certificates, for sailplanes and powered sailplanes in the utility U and aerobatic A categories:
  (1)  Sailplanes the maximum weight of which does not exceed 750 kg:
  (2)  Single engine (spark- or compression-ignition) powered sailplanes the design value W/b2 (weight to span2) of which is not greater than 3(W[kg], b[m]) and the maximum weight of which does not exceed 850 kg: and
  (3)  Sailplanes and powered sailplanes the number of occupants of which does not exceed two.

The following is the applicable data for the Xenos "Motorglider:"

  • Number of occupants _______ 2
  • Maximum Weight __________ 580 kg (1275 pounds)
  • Maximum weight to span2____ 3.00 kg/m2 (0.61 lb./ft.2)

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