If certification with ditching provisions is requested, structural
strength for ditching must meet the requirements of this section and
§29.801(e).
(a) Forward speed landing conditions. The rotorcraft must
initially contact the most critical wave for reasonably probable water
conditions at forward velocities from zero up to 30 knots in likely pitch,
roll, and yaw attitudes. The rotorcraft limit vertical descent velocity
may not be less than 5 feet per second relative to the mean water surface.
Rotor lift may be used to act through the center of gravity throughout the
landing impact. This lift may not exceed two-thirds of the design maximum
weight. A maximum forward velocity of less than 30 knots may be used in
design if it can be demonstrated that the forward velocity selected would
not be exceeded in a normal one-engine-out touchdown.
(b) Auxiliary or emergency float conditions -- (1) Floats
fixed or deployed before initial water contact. In addition to the
landing loads in paragraph (a) of this section, each auxiliary or
emergency float, or its support and attaching structure in the airframe or
fuselage, must be designed for the load developed by a fully immersed
float unless it can be shown that full immersion is unlikely. If full
immersion is unlikely, the highest likely float buoyancy load must be
applied. The highest likely buoyancy load must include consideration of a
partially immersed float creating restoring moments to compensate the
upsetting moments caused by side wind, unsymmetrical rotorcraft loading,
water wave action, rotorcraft inertia, and probable structural damage and
leakage considered under §29.801(d). Maximum roll and pitch angles
determined from compliance with §29.801(d) may be used, if significant, to
determine the extent of immersion of each float. If the floats are
deployed in flight, appropriate air loads derived from the flight
limitations with the floats deployed shall be used in substantiation of
the floats and their attachment to the rotorcraft. For this purpose, the
design airspeed for limit load is the float deployed airspeed operating
limit multiplied by 1.11.
(2) Floats deployed after initial water contact. Each float must
be designed for full or partial immersion prescribed in paragraph (b)(1)
of this section. In addition, each float must be designed for combined
vertical and drag loads using a relative limit speed of 20 knots between
the rotorcraft and the water. The vertical load may not be less than the
highest likely buoyancy load determined under paragraph (b)(1) of this
section.