ED Decision 2003/13/RM
(a) Each requirement of this Subpart must be met at each appropriate combination of weight and c.g. within the range of loading conditions for which certification is requested. This must be shown:
(1) by test upon a sailplane of the type for which certification is requested or by calculations based on and equal in accuracy to the result of testing; and,
(2) by systematic investigation of each critical combination of weight and c.g.
(b) Compliance must be established for all configurations (such as position of air brakes, wing-flaps, landing gear etc.) at which the sailplane will be operated except as otherwise stated. In demonstrating compliance, the power-plant or propeller, if retractable, must be retracted, except as otherwise stated.