TM 1-1520-240-10
4-3-18
Figure 4-3-14. Forward and Aft Cargo Hooks
CAUTION
The forward and aft hooks may fail to open
if the slings are slack when the release
solenoids are energized (a load of approx-
imately 20 pounds is required for open-
ing). The hooks can be opened by select-
ing the desired hook(s) and depressing
the release switch as the aircraft is lifted to
apply tension to the slings.
e.
CARGO HOOK EMERG Switch. The emergen-
cy cargo hook release switch is on the CARGO HOOK
control panel. It is a guarded switch and it is labeled
EMERG REL ALL (emergency release all). The switch is
used to simultaneously open the three hooks, if an emer-
gency situation develops. The three hooks will open re-
gardless of CARGO HOOK MSTR or HOOK SEL switch
positions. Setting the switch to REL ALL, energizes an
emergency hook release relay. The relay then energizes
release solenoids in the forward and aft hooks and a
solenoid valve in the center hook. The solenoid valve in
the center hook releases the aircharge stored in the low-
er half of the hydraulic actuator, transferring the charge
to the upper (release) half of the actuator to open the
hook. After this method of opening the hook, the hook
actuator must be recharged to 2,000 to 2,100 psi. The
emergency hook release relay will automatically deener-
gized after a 10 second time delay. This prevents dam-
age to the hook release solenoids.
CAUTION
Before external load operations, crew–
members shall familiarize themselves
with the manual emergency cargo release
mechanism installed on the helicopter
WARNING
When the center cargo hook is opened
with the external load off the ground, the
cargo hook will whip back back and forth.
CAUTION
When the center cargo hook is opened us-
ing the manual emergency release handle,
the hook must be closed manually. No at-
tempt should be made to close the hook
using the normal hydraulic or pneumatic
method, since damage to the cargo hook
can result.
