507 

Federal Aviation Administration, DOT 

§ 27.563 

10

° 

lateral roll, with the directions op-

tional, 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 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

t

t

1

t

t

a(t)dt

2

1

2

1

t

t

2.5

1

2

=

−

(

)

−

(

)

⎡

⎣

⎢

⎢

⎤

⎦

⎥

⎥

∫

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

2

¥ 

t

1

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 

VerDate Sep<11>2014 

12:50 Apr 30, 2019

Jkt 247046

PO 00000

Frm 00517

Fmt 8010

Sfmt 8010

Y:\SGML\247046.XXX

247046

EC28SE91.084</MATH>

spaschal on DSK3GDR082PROD with CFR