2.1 The requirements of this paragraph are applicable
for crew and revenue seats in craft having a design collision load
of less than 3 g.
2.2 All seats to which this paragraph applies,
along with their supports and deck attachments, should be designed
to withstand at least the following static forces applied in the direction
of the craft:
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.1 Forward direction: a force of 2.25 kN,
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.2 After direction: a force of 1.5 kN,
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.3 Transverse direction: a force of 1.5 kN,
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.4 Vertically downward: a force of 2.25 kN, and
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.5 Vertically upward: a force of 1.5 kN.
If these forces are applied in the fore or aft direction of
the seat, they should be applied horizontally to the seat back 350
mm above the seat bottom. If the forces are applied in the transverse
seat direction, they should be applied horizontally to the seat bottom.
Vertical upward forces should be evenly distributed to the corners
of seat bottom frame. Vertical downward forces should be uniformly
distributed over the seat bottom.
If a seating unit consists
of more than one seating position, these forces should be applied
at each seating position concurrently during the tests.
2.3 When the forces are applied to a seat, consideration
should be given to the direction in which the seat is to face in the
craft. For example, if the seat faces sideways, the transverse craft
force would be applied fore and aft on the seat and the forward craft
force would be applied transversely on the seat.
2.4 Each seating unit to be tested should be attached
to the support structure similar to the manner in which it will be
attached to the deck structure in the craft. Although a rigid support
structure can be used for these tests, a support structure, having
the same strength and stiffness as the support structure in the craft,
is preferred.
2.5 The forces described in 2.2.1 to 2.2.3 should
be applied to the seat through a cylindrical surface having a radius
of 82 mm and a width at least equal to the width of the seat. The
surface should be equipped with at least one force transducer able
to measure the forces specified.
2.6 The seat should be considered acceptable if:
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.1 under the influence of the forces referred
to in 2.2.1 to 2.2.3, the permanent displacement measured at the point
of application of the force is not more than 400 mm;
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.2 no part of the seat, the seat mountings or
the accessories become completely detached during the tests;
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.3 the seat remains firmly held, even if one or
more of the anchorages is partly detached, and all of the locking
systems remain locked during the whole duration of the test (adjustment
and locking systems need not be operational after the tests); and
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.4 rigid parts of the seat with which the occupant
may come into contact should present a curved surface with a radius
of at least 5 mm.
2.7 The requirements of section 3 may be used
in lieu of the requirements of this section provided that the accelerations
used for the tests are at least 3 g.