8.2.5 The maximum load on the hook to allow for
automatic release loads should be determined as follows:
-
.1 the hook should be loaded with a mass of 200
kg and the actuating mechanism set;
-
.2 the load should be reduced gradually in stages
until the hook releases automatically, but at not more than 30 kg,
to establish load F; and
-
.3 the load F should be measured
and recorded. The minimum allowable load F is the minimum
obtained at release which should be not less than 5 kg.
8.2.6 The hook should be loaded with a mass of
200 kg and the actuating mechanism set. The hook should then be subjected
to cyclic loading between 30 kg and 200 kg using a frequency of 1
± 0.2 Hz. The hook should not release before 300 cycles. The
number of cycles at which the hook opened or whether the test was
discontinued at 300 cycles should be recorded.
8.2.7 The hook should then be reloaded to 200
kg and the actuating mechanism set. The hook should be subjected to
a cyclic loading, the upper limit of which is +200 kg, and the lower
limit being F1 using a frequency of 1 ± 0.2 Hz.
The automatic release mechanism should operate within three cycles.
The number of cycles at which the hook opened or whether the test
was discontinued after three cycles should be recorded. F1
is to be taken as the minimum load on the hook to allow for automatic
release, as established in 8.2.5.2, reduced by 2 kg.
8.2.8 The hook should be attached to a short wire
rope fall, approximately 1.5 m, and loaded with a mass of 10 kg. The
weight should be secured and then lifted 1 m. From this position it
should be released to perform a free fall before it is abruptly stopped
by the wire rope fall. The hook should not release as a result of
this test.
8.2.9 The automatic release hook should be attached
to a test load equal to 1.1 times the safe working load, with the
actuating mechanism in the locked position. The load should be raised
to a height of at least 6 m and then be lowered at a speed of 0.6
m/s. When the load is 1.5 m above the ground or water surface, the
actuating mechanism should be set for automatic release, and the lowering
completed. The automatic release hook should release the load when
it strikes the ground or water surface. The test should be repeated
with a test load equal to 2.2 times the safe working load.
8.2.10 The automatic release hook should be attached
to a test load of 1.1 times its maximum working load using an approved
launching appliance. The test load should be lowered at maximum lowering
speed through a distance of at least 3 m and stopped by applying the
hand brake sharply. This test should be conducted twice, once with
the release mechanism set for automatic release, and again with the
mechanism set to closed. The release mechanism should not open in
either test.
8.2.11 The hook should be loaded to 0, 25%, 50%,
75% and 100% of the safe working load of the hook. At each load level,
the actuating force required at the actuating mechanism should be
measured and recorded. The actuating force should be between 150 and
250 N if the hook is lanyard-operated, or the action required to set
the actuating mechanism should be readily performed by a single person
without difficulty.
8.2.12 The securing force, which should be less
than 120 N, should be determined with an unloaded hook and should
be recorded.
8.2.13 The manual release force should be determined
as follows:
-
.1 the hook should be loaded with a mass of 150
kg;
-
.2 the actuating mechanism should be set;
-
.3 the force required to release the hook manually
should be established and recorded; and
-
.4 the manual release force for a mass of 150
kg on the hook should be at least 600 N for lanyard-operated designs.
Alternative designs should be demonstrated to the satisfaction of
the Administration to provide adequate protection from inadvertent
release under load.
8.2.14 The automatic release hook should be attached
to a test load equal to the mass of the lightest liferaft for which
the automatic release hook is to be approved, with the actuating mechanism
in the locked position (i.e. not set for automatic release). The load
should then be raised so that it is clear of the ground. The actuating
mechanism should be set to automatic release. This should be easily
accomplished by a single person and should not release the load.
8.2.15 The hook should be released 100 times without
failure by each of its modes of release using the maximum load permitting
release for that mode. It should then be disassembled and the parts
examined. There should be no evidence of excessive wear on any part.
8.2.16 The hook should be arranged in a cold store
at -30°C to simulate operational readiness and loaded with 25kg.
A 3.5 cm thick uniform of layer of icing should be built onto it by
spraying cold fresh water from angles above 45° from horizontal,
with intermittent pauses to let icing form. The hook should then be
actuated and as a result release the hold without failure.
8.2.17 It should be demonstrated that the hook
is not damaged as a result of 10 impacts at a horizontal speed of
3.5m/s on to a structure resembling a vertical ship's side. As far
as practical all sides of the hook, especially areas with exposed
controls, should impact the structure. The hook should not sustain
any damage which will interfere with the normal function of the hook.