ED Decision 2003/16/RM
(a) Strength requirements are specified in terms of limit loads (the maximum loads to be expected in service) and ultimate loads (limit loads multiplied by prescribed factors of safety). Unless otherwise provided, prescribed loads are limit loads.
(b) Unless otherwise provided, the specified air, ground, and water loads must be placed in equilibrium with inertia forces, considering each item of mass in the rotorcraft. These loads must be distributed to closely approximate or conservatively represent actual conditions.
(c) If deflections under load would significantly change the distribution of external or internal loads, this redistribution must be taken into account.
ED Decision 2003/16/RM
Unless otherwise provided, a factor of safety of 1.5 must be used. This factor applies to external and inertia loads unless its application to the resulting internal stresses is more conservative.
CS 29.305 Strength and deformation
ED Decision 2003/16/RM
(a) The structure must be able to support limit loads without detrimental or permanent deformation. At any load up to limit loads, the deformation may not interfere with safe operation.
(b) The structure must be able to support ultimate loads without failure. This must be shown by:
(1) Applying ultimate loads to the structure in a static test for at least 3 seconds; or
(2) Dynamic tests simulating actual load application.
ED Decision 2003/16/RM
(a) Compliance with the strength and deformation requirements of this Subpart must be shown for each critical loading condition accounting for the environment to which the structure will be exposed in operation. Structural analysis (static or fatigue) may be used only if the structure conforms to those for which experience has shown this method to be reliable. In other cases, substantiating load tests must be made.
(b) Proof of compliance with the strength requirements of this Subpart must include:
(1) Dynamic and endurance tests of rotors, rotor drives, and rotor controls;
(2) Limit load tests of the control system, including control surfaces;
(3) Operation tests of the control system;
(4) Flight stress measurement tests;
(5) Landing gear drop tests; and
(6) Any additional tests required for new or unusual design features.
ED Decision 2003/16/RM
The following values and limitations must be established to show compliance with the structural requirements of this Subpart:
(a) The design maximum and design minimum weights.
(b) The main rotor rpm ranges, power on and power off.
(c) The maximum forward speeds for each main rotor rpm within the ranges determined under sub-paragraph (b).
(d) The maximum rearward and sideward flight speeds.
(e) The centre of gravity limits corresponding to the limitations determined under sub-paragraphs (b), (c) and (d).
(f) The rotational speed ratios between each powerplant and each connected rotating component.
(g) The positive and negative limit manoeuvring load factors.