UP F RONT
aircraftinteriorsinternational.com
010 SEPTEMBER 2019
1. IN THE EVENT OF A
DECOMPRESSION HOLE APPEARING
IN THE ADJACENT FUSELAGE, THAT
DAMAGE WOULD POSE A GREATER
THREAT TO A SUITE OCCUPANT
THAN THE COLLAPSE OF A
PARTITION WALL
PANEL DISCUSSION
The FAA is proposing changes to the Part 25 requirements for non-structural partitions, which
could improve aircraft structural integrity and compartment design, and simplify certification
Designers of certain small aircraft cabin compartments, such as
lavatories, private suites and crew rest areas may find their work a little
easier in the future, if an FAA proposal is passed. The agency is looking
to revise standard 25.365, “Pressurised compartment loads,” in Title 14,
Code of Federal Regulations (14 CFR) Part 25, such that non-structural
partitions (any non-structural wall, floor or ceiling panel) need not be
designed to withstand “significant” decompression holes in the
fuselage skin. Such major damage to the fuselage could be caused by
an event such as a fatigue failure, an engine rotor burst, or an explosive
or incendiary device.
It can be difficult to achieve compliance with 25.365(g) because
a large decompression hole occurring in such a compartment
would result in very high air loads on the partitions that form the
compartment. Compliance is typically demonstrated by either
strengthening the partition to the extent that it would not fail, adding
sufficient venting to reduce the loads on the partition, or a combination
of the two measures. The FAA states that in some cases, both of these
approaches have been shown to be impractical because the resulting
design can compromise the airplane’s structural integrity or indeed the
compartment’s intended function.
For example, strengthening the partition to the extent that it would
not fail can increase the loads on the floor and thereby the potential
for a more serious floor failure, which could jeopardise continued safe
CURTAINS UP?
1
flight, either through
structural failure or by
damaging control systems
routed through the floor.
Adding venting would
reduce loads on the
partition, but in some
cases it is not possible
to add enough venting
while also maintaining
the purpose of the
compartment. A more
obvious point is that if a
large decompression hole
occurs in a compartment,
the risk to occupants from
the decompression itself
is likely to exceed that of
a collapse of the partition.
Therefore, the FAA proposes to revise this section to allow the failure
of partitions immediately adjacent to the decompression hole, provided
the failure would not compromise the structural integrity of the aircraft,
and that meeting the current conditions would be impractical.
According to the FAA this proposal would not compromise safety
because it conforms the regulatory text to long-standing FAA practice
established through equivalent level of safety findings and methods of
compliance for small compartment design. The proposal would also
improve certification efficiency by eliminating the need for design-bydesign
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equivalent level of safety analyses to allow for such partition
design. Partition failure due to less significant decompression events
would continue to be prohibited because it is practical to design
partitions to withstand those events.
The FAA has invited interested parties to submit comments, data
or views relating to the proposals. The agency may change the proposal
in light of any comments it receives.
A solid door is fundamental
to the intended use of
compartments such as lavs,
remote crew rests or private
suites. While using a curtain
in place of a solid door would
improve the decompression
capability of the compartment
and is physically practical for
compliance with 25.365(g), the
FAA accepts that changing the
door to a curtain in these
instances would be impractical
because the resulting design
would not fulfill the purpose
of the compartment.
STAYING SECURE
Standard 25.365(g) requires that
reasonable design precautions are
taken to minimise the probability of
parts such as failed partitions
becoming detached and injuring
seated occupants following a
decompression event. This proposal
would not change that requirement.
For example, lanyards or other
devices can be used to reduce the
chance that a failed partition will hit
an occupant, in which case venting
would also have to be added as a
precaution, to reduce the risk a
partition will fail as a result of
smaller decompression holes.
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