Sec. 25.783 - Doors.
(a) Each cabin must have at least one
easily accessible external door.
(b) There must be a means to lock and
safeguard each external door against opening in flight (either
inadvertently by persons or as a result of mechanical failure or failure
of a single structural element either during or after closure). Each
external door must be openable from both the inside and the outside, even
though persons may be crowded against the door on the inside of the
airplane. Inward opening doors may be used if there are means to prevent
occupants from crowding against the door to an extent that would interfere
with the opening of the door. The means of opening must be simple and
obvious and must be arranged and marked so that it can be readily located
and operated, even in darkness. Auxiliary locking devices may be used.
(c) Each external door must be
reasonably free from jamming as a result of fuselage deformation in a
(d) Each external door must be located
where persons using them will not be endangered by the propellers when
appropriate operating procedures are used.
(e) There must be a provision for direct
visual inspection of the locking mechanism to determine if external doors,
for which the initial opening movement is not inward (including passenger,
crew, service, and cargo doors), are fully closed and locked. The
provision must be discernible under operational lighting conditions by
appropriate crewmembers using a flashlight or equivalent lighting source.
In addition, there must be a visual warning means to signal the
appropriate flight crewmembers if any external door is not fully closed
and locked. The means must be designed such that any failure or
combination of failures that would result in an erroneous closed and
locked indication is improbable for doors for which the initial opening
movement is not inward.
(f) External doors must have provisions
to prevent the initiation of pressurization of the airplane to an unsafe
level if the door is not fully closed and locked. In addition, it must be
shown by safety analysis that inadvertent opening is extremely improbable.
(g) Cargo and service doors not suitable
for use as emergency exits need only meet paragraphs (e) and (f) of this
section and be safeguarded against opening in flight as a result of
mechanical failure or failure of a single structural element.
(h) Each passenger entry door in the
side of the fuselage must meet the applicable requirements of §§25.807
through 25.813 for a Type II or larger passenger emergency exit.
(i) If an integral stair is installed in
a passenger entry door that is qualified as a passenger emergency exit,
the stair must be designed so that under the following conditions the
effectiveness of passenger emergency egress will not be impaired:
(1) The door, integral stair, and
operating mechanism have been subjected to the inertia forces specified in
§25.561(b)(3), acting separately relative to the surrounding structure.
(2) The airplane is in the normal ground
attitude and in each of the attitudes corresponding to collapse of one or
more legs of the landing gear.
(j) All lavatory doors must be designed
to preclude anyone from becoming trapped inside the lavatory, and if a
locking mechanism is installed, it be capable of being unlocked from the
outside without the aid of special tools.
[Doc. No. 5066, 29 FR 18291, Dec. 24, 1964, as
amended by Amdt. 25-15, 32 FR 13262, Sept. 20, 1967; Amdt. 25-23, 35 FR
5676, Apr. 8, 1970; Amdt. 25-54, 45 FR 60173, Sept. 11, 1980; Amdt. 25-72,
55 FR 29780, July 20, 1990; Amdt. 25-88, 61 FR 57956, Nov. 8, 1996]