Text in force at 23-63: from 23-48, effective 11 Mar 1996.
[(a) If a rear lift truss is used, it must be designed to withstand conditions of reversed airflow at a design speed of-- V = 8.7 + 8.7 (knots) where-- W/S = wing loading at design maximum takeoff weight.]
(b) Either aerodynamic data for the particular wing section used, or a value of CL equalling -0.8 with a chordwise distribution that is triangular between a peak at the trailing edge and zero at the leading edge, must be used.
61 FR 5145 · Source