title-14-part-27-sec27-562

507

Federal Aviation Administration, DOT

§ 27.562

(2) The wheels are retracted (where

applicable); and

(3) Each occupant and each item of

mass inside the cabin that could injure
an occupant is restrained when sub-
jected to the following ultimate iner-
tial load factors relative to the sur-
rounding structure:

(i) Upward—4g.
(ii) Forward—16g.
(iii) Sideward—8g.
(iv) Downward—20g, after intended

displacement of the seat device.

(v) Rearward—1.5g.
(c) The supporting structure must be

designed to restrain, under any ulti-
mate inertial load up to those specified
in this paragraph, any item of mass
above and/or behind the crew and pas-
senger compartment that could injure
an occupant if it came loose in an
emergency landing. Items of mass to be
considered include, but are not limited
to, rotors, transmissions, and engines.
The items of mass must be restrained
for the following ultimate inertial load
factors:

(1) Upward—1.5g.
(2) Forward—12g.
(3) Sideward—6g.
(4) Downward—12g.
(5) Rearward—1.5g
(d) Any fuselage structure in the area

of internal fuel tanks below the pas-
senger floor level must be designed to
resist the following ultimate inertial
factors and loads and to protect the
fuel tanks from rupture when those
loads are applied to that area:

(i) Upward—1.5g.
(ii) Forward—4.0g.
(iii) Sideward—2.0g.
(iv) Downward—4.0g.

[Doc. No. 5074, 29 FR 15695, Nov. 24, 1964, as
amended by Amdt. 27–25, 54 FR 47318, Nov. 13,
1989; Amdt. 27–30, 59 FR 50386, Oct. 3, 1994;
Amdt. 27–32, 61 FR 10438, Mar. 13, 1996]

§ 27.562

Emergency landing dynamic

conditions.

(a) The rotorcraft, although it may

be damaged in an emergency crash
landing, must be designed to reason-
ably protect each occupant when—

(1) The occupant properly uses the

seats, safety belts, and shoulder har-
nesses provided in the design; and

(2) The occupant is exposed to the

loads resulting from the conditions
prescribed in this section.

(b) Each seat type design or other

seating device approved for crew or
passenger occupancy during takeoff
and landing must successfully com-
plete dynamic tests or be demonstrated
by rational analysis based on dynamic
tests of a similar type seat in accord-
ance with the following criteria. The
tests must be conducted with an occu-
pant, simulated by a 170-pound
anthropomorphic test dummy (ATD),
as defined by 49 CFR 572, subpart B, or
its equivalent, sitting in the normal
upright position.

(1) A change in downward velocity of

not less than 30 feet per second when
the seat or other seating device is ori-
ented in its nominal position with re-
spect to the rotorcraft’s reference sys-
tem, the rotorcraft’s longitudinal axis
is canted upward 60

with respect to

the impact velocity vector, and the
rotorcraft’s lateral axis is perpen-
dicular to a vertical plane containing
the impact velocity vector and the
rotorcraft’s longitudinal axis. Peak
floor deceleration must occur in not
more than 0.031 seconds after impact
and must reach a minimum of 30g’s.

(2) A change in forward velocity of

not less than 42 feet per second when
the seat or other seating device is ori-
ented in its nominal position with re-
spect to the rotorcraft’s reference sys-
tem, the rotorcraft’s longitudinal axis
is yawed 10

either right or left of the

impact velocity vector (whichever
would cause the greatest load on the
shoulder harness), the rotorcraft’s lat-
eral axis is contained in a horizontal
plane containing the impact velocity
vector, and the rotorcraft’s vertical
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 min-
imum of 18.4g’s.

(3) Where floor rails or floor or side-

wall attachment devices are used to at-
tach the seating devices to the air-
frame structure for the conditions of
this section, the rails or devices must
be misaligned with respect to each
other by at least 10

vertically (i.e.,

pitch out of parallel) and by at least a

VerDate Sep<11>2014

09:06 Jun 28, 2024

Jkt 262046

PO 00000

Frm 00517

Fmt 8010

Sfmt 8010

Y:\SGML\262046.XXX

262046

jspears on DSK121TN23PROD with CFR

508

14 CFR Ch. I (1–1–24 Edition)

§ 27.563

lateral roll, with the directions op-

tional, to account for possible floor
warp.

must be shown:

(1) The seating device system must

remain intact although it may experi-
ence separation intended as part of its
design.

(2) The attachment between the seat-

ing 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 im-
mediate 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 pas-
senger 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.

HIC

a(t)dt

2.5

−

(

)

−

(

)

⎡

⎣

⎢

⎤

⎦

⎥

∫

Where: a(t) is the resultant acceleration at

the center of gravity of the head form ex-
pressed as a multiple of g (the accelera-
tion of gravity) and t

is the time

duration, in seconds, of major head im-
pact, 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 re-
taining the upper torso, the total har-
ness 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.

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

§ 27.563

Structural ditching provi-

sions.

If certification with ditching provi-

sions is requested, structural strength

for ditching must meet the require-
ments of this section and § 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 sur-
face. Rotor lift may be used to act
through the center of gravity through-
out 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 dem-
onstrated that the forward velocity se-
lected would not be exceeded in a nor-
mal one-engine-out touchdown.

(b)

Auxiliary or emergency float condi-

tions—(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 devel-
oped 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 consider-
ation of a partially immersed float cre-
ating restoring moments to com-
pensate the upsetting moments caused
by side wind, unsymmetrical rotorcraft
loading, water wave action, rotorcraft
inertia, and probable structural dam-
age and leakage considered under
§ 27.801(d). Maximum roll and pitch an-
gles determined from compliance with
§ 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 sub-
stantiation of the floats and their at-
tachment to the rotorcraft. For this
purpose, the design airspeed for limit
load is the float deployed airspeed op-
erating limit multiplied by 1.11.

(2)

Floats deployed after initial water

contact. Each float must be designed for
full or partial immersion perscribed in