spaschal on DSK3GDR082PROD with CFR

Section 25.783

14 CFR Ch. I (1-1-19 Edition)

(2) Each door that could be a hazard
if it unlatches must be designed so that
unlatching during pressurized and unpressurized flight from the fully closed,
latched, and locked condition is extremely improbable. This must be
shown by safety analysis.
(3) Each element of each door operating system must be designed or,
where impracticable, distinctively and
permanently marked, to minimize the
probability of incorrect assembly and
adjustment that could result in a malfunction.
(4) All sources of power that could
initiate unlocking or unlatching of any
door must be automatically isolated
from the latching and locking systems
prior to flight and it must not be possible to restore power to the door during flight.
(5) Each removable bolt, screw, nut,
pin, or other removable fastener must
meet the locking requirements of
Section 25.607.
(6) Certain doors, as specified by
Section 25.807(h), must also meet the applicable requirements of SectionSection 25.809 through
25.812 for emergency exits.
(b) Opening by persons. There must be
a means to safeguard each door against
opening during flight due to inadvertent action by persons. In addition,
design precautions must be taken to
minimize the possibility for a person to
open a door intentionally during flight.
If these precautions include the use of
auxiliary devices, those devices and
their controlling systems must be designed so that - 
(1) No single failure will prevent
more than one exit from being opened;
and
(2) Failures that would prevent opening of the exit after landing are improbable.
(c) Pressurization prevention means.
There must be a provision to prevent
pressurization of the airplane to an unsafe level if any door subject to pressurization is not fully closed, latched,
and locked.
(1) The provision must be designed to
function after any single failure, or
after any combination of failures not
shown to be extremely improbable.
(2) Doors that meet the conditions
described in paragraph (h) of this section are not required to have a dedi-

cated pressurization prevention means
if, from every possible position of the
door, it will remain open to the extent
that it prevents pressurization or safely close and latch as pressurization
takes place. This must also be shown
with any single failure and malfunction, except that - 
(i) With failures or malfunctions in
the latching mechanism, it need not
latch after closing; and
(ii) With jamming as a result of mechanical failure or blocking debris, the
door need not close and latch if it can
be shown that the pressurization loads
on the jammed door or mechanism
would not result in an unsafe condition.
(d) Latching and locking. The latching
and locking mechanisms must be designed as follows:
(1) There must be a provision to latch
each door.
(2) The latches and their operating
mechanism must be designed so that,
under all airplane flight and ground
loading conditions, with the door
latched, there is no force or torque
tending to unlatch the latches. In addition, the latching system must include
a means to secure the latches in the
latched position. This means must be
independent of the locking system.
(3) Each door subject to pressurization, and for which the initial opening
movement is not inward, must - 
(i) Have an individual lock for each
latch;
(ii) Have the lock located as close as
practicable to the latch; and
(iii) Be designed so that, during pressurized flight, no single failure in the
locking system would prevent the
locks from restraining the latches necessary to secure the door.
(4) Each door for which the initial
opening movement is inward, and
unlatching of the door could result in a
hazard, must have a locking means to
prevent the latches from becoming disengaged. The locking means must ensure sufficient latching to prevent
opening of the door even with a single
failure of the latching mechanism.
(5) It must not be possible to position
the lock in the locked position if the
latch and the latching mechanism are
not in the latched position.

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VerDate Sep<11>2014

12:50 Apr 30, 2019

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