Federal Aviation Administration, DOT

Section 27.563

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
HIC = ( t 2  -  t 1 ) -
 -  ( t 2  -  t 1 )

t2

 - t

1

-
a(t)dt -
 - 

2.5

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.

(6) Loads in individual upper torso
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.
(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.

Section 27.563 Structural
sions.

ditching

provi-

If certification with ditching provisions is requested, structural strength

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[Amdt. 27-25, 54 FR 47318, Nov. 13, 1989]

for ditching must meet the requirements of this section and Section 27.801(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, of 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 27.801(d). Maximum roll and pitch angles determined from compliance with
Section 27.801(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 perscribed in