421
Federal Aviation Administration, DOT
§ 25.562
g=acceleration due to gravity (ft./sec.
2
).
(g)
Float bottom pressures. The float
bottom pressures must be established
under § 25.533, except that the value of
K
2
in the formulae may be taken as 1.0.
The angle of dead rise to be used in de-
termining the float bottom pressures is
set forth in paragraph (b) of this sec-
tion.
[Doc. No. 5066, 29 FR 18291, Dec. 24, 1964, as
amended by Amdt. 25–23, 35 FR 5673, Apr. 8,
1970]
§ 25.537
Seawing loads.
Seawing design loads must be based
on applicable test data.
E
MERGENCY
L
ANDING
C
ONDITIONS
§ 25.561
General.
(a) The airplane, although it may be
damaged in emergency landing condi-
tions on land or water, must be de-
signed as prescribed in this section to
protect each occupant under those con-
ditions.
(b) The structure must be designed to
give each occupant every reasonable
chance of escaping serious injury in a
minor crash landing when—
(1) Proper use is made of seats, belts,
and all other safety design provisions;
(2) The wheels are retracted (where
applicable); and
(3) The occupant experiences the fol-
lowing ultimate inertia forces acting
separately relative to the surrounding
structure:
(i) Upward, 3.0g
(ii) Forward, 9.0g
(iii) Sideward, 3.0g on the airframe;
and 4.0g on the seats and their attach-
ments.
(iv) Downward, 6.0g
(v) Rearward, 1.5g
(c) For equipment, cargo in the pas-
senger compartments and any other
large masses, the following apply:
(1) Except as provided in paragraph
(c)(2) of this section, these items must
be positioned so that if they break
loose they will be unlikely to:
(i) Cause direct injury to occupants;
(ii) Penetrate fuel tanks or lines or
cause fire or explosion hazard by dam-
age to adjacent systems; or
(iii) Nullify any of the escape facili-
ties provided for use after an emer-
gency landing.
(2) When such positioning is not prac-
tical (e.g. fuselage mounted engines or
auxiliary power units) each such item
of mass shall be restrained under all
loads up to those specified in paragraph
(b)(3) of this section. The local attach-
ments for these items should be de-
signed to withstand 1.33 times the spec-
ified loads if these items are subject to
severe wear and tear through frequent
removal (e.g. quick change interior
items).
(d) Seats and items of mass (and
their supporting structure) must not
deform under any loads up to those
specified in paragraph (b)(3) of this sec-
tion in any manner that would impede
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
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