§29.519 Hull type rotorcraft: Water- based and amphibian

(a) General. For hull ty pe rotorcraft, the structure must be desi gned t o wi thstand the water loading set fort h i n sub-paragraphs (b), (c), and (d) consi dering the most severe wave heights and profiles for whi ch approval i s desi red. The l oads for the l anding condi tions of sub-paragraphs (b) and (c) must be devel oped and di stributed al ong and among the hull and auxiliary floats, if used, in a rational and conservat ive m anner, assum ing a rotor lift not exceeding two-thirds of the rotorcraft weight to act throughout the landing impact. (b) Vertical conditions. The landing rotorcraft must initially co ntact th e m ost critical wave surface at zero forward speed in likely pitch and roll attitudes wh ich resu lt in critical d esign loadings. The vertical descent velocity may not be less than 1.98 m etres per second (6.5 ft /s) relative to the mean water surface. (c) Forward speed landing conditions. The rotorcraft m ust contact th e m ost critical wave at forward v elocities fro m zero u p to 5 6 k m/h (3 0 knots) in likely pitch, roll, and yaw attitudes and with a v ertical d escent v elocity of not less than 1.98 m etres per second (6.5 ft/s) relative to the mean water surface. A m aximum forward velocity of less t han 56 km /h (30 knot s) m ay be used i n design i f i t can be demonstrated that the forward velocity selected would not be exceeded in a normal one-engine-out landing. (d) Auxiliary float immersion condition. In addition t o t he l oads from t he l anding condi tions, the auxiliary float, and its support and attaching structure in the hull, must be designed for the load developed by a fully i mmersed fl oat unl ess i t can be sh own th at fu ll im mersion o f th e flo at is unlikely, in wh ich case th e h ighest lik ely float buoyancy l oad m ust be appl ied t hat considers loading o f th e flo at im mersed to create restoring moments com pensating for upset ting m oments caused by si de wi nd, as ymmetrical rotorcraft loading, water wave action and rotorcraft inertia.