260
14 CFR Ch. I (1–1–19 Edition)
§ 25.562
subsequent rapid evacuation of occu-
pants.
[Doc. No. 5066, 29 FR 18291, Dec. 24, 1964, as
amended by Amdt. 25–23, 35 FR 5673, Apr. 8,
1970; Amdt. 25–64, 53 FR 17646, May 17, 1988;
Amdt. 25–91, 62 FR 40706, July 29, 1997]
§ 25.562
Emergency landing dynamic
conditions.
(a) The seat and restraint system in
the airplane must be designed as pre-
scribed in this section to protect each
occupant during an emergency landing
condition when—
(1) Proper use is made of seats, safety
belts, and shoulder harnesses provided
for in the design; and
(2) The occupant is exposed to loads
resulting from the conditions pre-
scribed in this section.
(b) Each seat type design approved
for crew or passenger occupancy during
takeoff and landing must successfully
complete dynamic tests or be dem-
onstrated by rational analysis based on
dynamic tests of a similar type seat, in
accordance with each of the following
emergency landing conditions. The
tests must be conducted with an occu-
pant simulated by a 170-pound
anthropomorphic test dummy, as de-
fined by 49 CFR Part 572, Subpart B, or
its equivalent, sitting in the normal
upright position.
(1) A change in downward vertical ve-
locity (
D
v) of not less than 35 feet per
second, with the airplane’s longitu-
dinal axis canted downward 30 degrees
with respect to the horizontal plane
and with the wings level. Peak floor de-
celeration must occur in not more than
0.08 seconds after impact and must
reach a minimum of 14g.
(2) A change in forward longitudinal
velocity (
D
v) of not less than 44 feet
per second, with the airplane’s longitu-
dinal axis horizontal and yawed 10 de-
grees either right or left, whichever
would cause the greatest likelihood of
the upper torso restraint system
(where installed) moving off the occu-
pant’s shoulder, and with the wings
level. Peak floor deceleration must
occur in not more than 0.09 seconds
after impact and must reach a min-
imum of 16g. Where floor rails or floor
fittings are used to attach the seating
devices to the test fixture, the rails or
fittings must be misaligned with re-
spect to the adjacent set of rails or fit-
tings by at least 10 degrees vertically
(
i.e.
, out of Parallel) with one rolled 10
degrees.
(c) The following performance meas-
ures must not be exceeded during the
dynamic tests conducted in accordance
with paragraph (b) of this section:
(1) Where upper torso straps are used
for crewmembers, tension loads in indi-
vidual straps must not exceed 1,750
pounds. If dual straps are used for re-
straining the upper torso, the total
strap tension loads must not exceed
2,000 pounds.
(2) The maximum compressive load
measured between the pelvis and the
lumbar column of the anthropomorphic
dummy must not exceed 1,500 pounds.
(3) The upper torso restraint straps
(where installed) must remain on the
occupant’s shoulder during the impact.
(4) The lap safety belt must remain
on the occupant’s pelvis during the im-
pact.
(5) Each occupant must be protected
from serious head injury under the con-
ditions prescribed in paragraph (b) of
this section. Where head contact with
seats or other structure can occur, pro-
tection must be provided so that the
head impact does not exceed a Head In-
jury Criterion (HIC) of 1,000 units. The
level of HIC is defined by the equation:
HIC
t
t
t
t
a t dt
t
t
=
−
(
)
−
(
)
⎡
⎣
⎢
⎢
⎤
⎦
⎥
⎥
⎧
⎨
⎪
⎩⎪
⎫
⎬
⎪
⎭⎪
∫
2
1
2
1
2 5
1
1
2
( )
.
max
Where:
t
1
is the initial integration time,
t
2
is the final integration time, and
a(t) is the total acceleration vs. time curve
for the head strike, and where
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