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EAA Clarifies Motorglider Certification Issue
October 7, 2021 – EAA has clarified an FAA guidance issue that had been a point of confusion in the certification of experimental self-launching gliders. When the FAA most recently revised Order 8130.2J, they removed a paragraph that gave inspectors and designated airworthiness representatives (DARs) special instructions on the certification of gliders. While the deletion was for the sake of consistency, it inadvertently removed a reference to a guidance document on what constitutes a self-launching glider.
This is important because it is up to the DAR or inspector to use their discretion in choosing an aircraft’s category and class to assign through its operating limitations. Absent any design standard, there is not a concrete distinction between a self-launching glider and an airplane. The FAA’s definition in FAR 1.1 is simply “a heavier-than-air aircraft, that is supported in flight by the dynamic reaction of the air against its lifting surfaces and whose free flight does not depend principally on an engine.” This lack of clarity had the potential to complicate certification in the field, with inspectors charged with individually drawing the distinction between airplane and glider.
The FAA policy staff has confirmed to EAA that the previously referenced advisory circular, AC 21.17-2, remains valid guidance despite it not being referenced in the order. They are considering adding the reference back in the next revision.
AC 21.17-2 defines a self-launching glider as:
a) The number of occupants does not exceed two
b) Maximum weight does not exceed 850 kg (1874 pounds), and
c) The maximum weight to wing span squared (w/b2) does not exceed 3.0 kg/m2 (0.62 lb./ft.2)
This definition covers most popular self-launching gliders, such as the Sonex Xenos with the extended wingtip option. The definition does not cover several designs certified as self-launching gliders in Europe under EASA standards, however. EAA supports the FAA’s use of AC 21.17-2, while maintaining flexibility for alternative standards when appropriate.