Federal Aviation Administration, DOT Section 29.563 axis is perpendicular to a horizontal plane containing the impact velocity vector. Peak floor deceleration must occur in not more than 0.071 seconds after impact and must reach a minimum of 18.4g-s. (3) Where floor rails or floor or sidewall attachment devices are used to attach the seating devices to the airframe structure for the conditions of this section, the rails or devices must be misaligned with respect to each other by at least 10Section vertically (i.e., pitch out of parallel) and by at least a 10Section lateral roll, with the directions optional, to account for possible floor warp. (c) Compliance with the following must be shown: (1) The seating device system must remain intact although it may experience separation intended as part of its design. (2) The attachment between the seating device and the airframe structure must remain intact although the structure may have exceeded its limit load. (3) The ATD-s shoulder harness strap or straps must remain on or in the immediate vicinity of the ATD-s shoulder during the impact. (4) The safety belt must remain on the ATD-s pelvis during the impact. (5) The ATD-s head either does not contact any portion of the crew or passenger compartment or, if contact is made, the head impact does not exceed a head injury criteria (HIC) of 1,000 as determined by this equation. - 1 - t2 HIC = ( t 2 - t 1 ) - a(t)dt - - - - ( t 2 - t 1 ) t1 2.5 (6) Loads in individual shoulder harness straps must not exceed 1,750 pounds. If dual straps are used for retaining the upper torso, the total harness strap loads must not exceed 2,000 pounds. (7) The maximum compressive load measured between the pelvis and the lumbar column of the ATD must not exceed 1,500 pounds. [Amdt. 29-29, 54 FR 47320, Nov. 13, 1989, as amended by Amdt. 29-41, 62 FR 46173, Aug. 29, 1997] Section 29.563 Structural ditching provisions. If certification with ditching provisions is requested, structural strength for ditching must meet the requirements of this section and Section 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 Section 29.801(d). Maximum roll and pitch angles determined from compliance with Section 29.801(d) may be used, if significant, to determine the extent of immersion of 597 VerDate Sep<11>2014 12:50 Apr 30, 2019 Jkt 247046 PO 00000 Frm 00607 Fmt 8010 Sfmt 8010 Y:\SGML\247046.XXX 247046 EC28SE91.088 spaschal on DSK3GDR082PROD with CFR Where: a(t) is the resultant acceleration at the center of gravity of the head form expressed as a multiple of g (the acceleration of gravity) and t2 Section t1 is the time duration, in seconds, of major head impact, not to exceed 0.05 seconds. (d) An alternate approach that achieves an equivalent or greater level of occupant protection, as required by this section, must be substantiated on a rational basis.