284 

14 CFR Ch. I (1–1–19 Edition) 

§ 25.785 

(4) The open door during flight would 

not create aerodynamic interference 
that could preclude safe flight and 
landing. 

(5) The airplane would meet the 

structural design requirements with 
the door open. This assessment must 
include the aeroelastic stability re-
quirements of § 25.629, as well as the 
strength requirements of subpart C of 
this part. 

(6) The unlatching or opening of the 

door must not preclude safe flight and 
landing as a result of interaction with 
other systems or structures. 

[Doc. No. 2003–14193, 69 FR 24501, May 3, 2004] 

§ 25.785

Seats, berths, safety belts, and 

harnesses. 

(a) A seat (or berth for a nonambu-

lant person) must be provided for each 
occupant who has reached his or her 
second birthday. 

(b) Each seat, berth, safety belt, har-

ness, and adjacent part of the airplane 
at each station designated as occupi-
able during takeoff and landing must 
be designed so that a person making 
proper use of these facilities will not 
suffer serious injury in an emergency 
landing as a result of the inertia forces 
specified in §§ 25.561 and 25.562. 

(c) Each seat or berth must be ap-

proved. 

(d) Each occupant of a seat that 

makes more than an 18-degree angle 
with the vertical plane containing the 
airplane centerline must be protected 
from head injury by a safety belt and 
an energy absorbing rest that will sup-
port the arms, shoulders, head, and 
spine, or by a safety belt and shoulder 
harness that will prevent the head 
from contacting any injurious object. 
Each occupant of any other seat must 
be protected from head injury by a 
safety belt and, as appropriate to the 
type, location, and angle of facing of 
each seat, by one or more of the fol-
lowing: 

(1) A shoulder harness that will pre-

vent the head from contacting any in-
jurious object. 

(2) The elimination of any injurious 

object within striking radius of the 
head. 

(3) An energy absorbing rest that will 

support the arms, shoulders, head, and 
spine. 

(e) Each berth must be designed so 

that the forward part has a padded end 
board, canvas diaphragm, or equivalent 
means, that can withstand the static 
load reaction of the occupant when 
subjected to the forward inertia force 
specified in § 25.561. Berths must be free 
from corners and protuberances likely 
to cause injury to a person occupying 
the berth during emergency conditions. 

(f) Each seat or berth, and its sup-

porting structure, and each safety belt 
or harness and its anchorage must be 
designed for an occupant weight of 170 
pounds, considering the maximum load 
factors, inertia forces, and reactions 
among the occupant, seat, safety belt, 
and harness for each relevant flight 
and ground load condition (including 
the emergency landing conditions pre-
scribed in § 25.561). In addition— 

(1) The structural analysis and test-

ing of the seats, berths, and their sup-
porting structures may be determined 
by assuming that the critical load in 
the forward, sideward, downward, up-
ward, and rearward directions (as de-
termined from the prescribed flight, 
ground, and emergency landing condi-
tions) acts separately or using selected 
combinations of loads if the required 
strength in each specified direction is 
substantiated. The forward load factor 
need not be applied to safety belts for 
berths. 

(2) Each pilot seat must be designed 

for the reactions resulting from the ap-
plication of the pilot forces prescribed 
in § 25.395. 

(3) The inertia forces specified in 

§ 25.561 must be multiplied by a factor 
of 1.33 (instead of the fitting factor pre-
scribed in § 25.625) in determining the 
strength of the attachment of each 
seat to the structure and each belt or 
harness to the seat or structure. 

(g) Each seat at a flight deck station 

must have a restraint system con-
sisting of a combined safety belt and 
shoulder harness with a single-point re-
lease that permits the flight deck occu-
pant, when seated with the restraint 
system fastened, to perform all of the 
occupant’s necessary flight deck func-
tions. There must be a means to secure 
each combined restraint system when 
not in use to prevent interference with 
the operation of the airplane and with 
rapid egress in an emergency. 

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