TM 55-1520-228-10
2-5. SEATS.
a. Pilot and Copilot/Observer Seats. The pilot
and copilot/ observer seats are constructed of tubing and
stretched nylon material. Each seat is equipped with
provisions for cushions, safety belts, and shoulder
harness. An inertia reel, with a manually operated
control handle, is incorporated on each seat. The inertia
reel is a mechanical restraining device that is designed
to hold the pilot in a normal seated position during any
maneuver which would tend to pitch the pilot forward.
Each reel is connected to a shoulder harness with a web
strap. An automatic locking mechanism, a webbing
roller, and a manual control are incorporated in each unit
(figure 2-3).
b. Passenger Seats. The passenger seats are
constructed of aluminum honeycomb panels and form an
integral part of the airframe. The center panel of the
seat back is removable to gain access to the fuel cell. Seats
are equipped with shoulder harness, safety belts, and
cushions. Seating is provided for two passengers or
without seats, space is provided for cargo (figure 2-3).
2-6. WIRE STRIKE PROTECTION SYSTEM (WSPS).
WARNING
Flight with the landing light in other than the
fully stowed position on OH58A/C aircraft
may degrade the effectiveness of the Wire
Strike Protection System (WSPS). When use
of the controllable landing light is not
anticipated, it should be in the fully stowed
position.
The WSPS provides protection against frontal impacts
with horizontally strung mechanical and
power transmission wires. The basic system consists of
an upper cutter assembly, a windshield deflector/cutter
assembly, and a lower cutter assembly (figure 2-1 and
figure 2-2). The windshield deflector/cutter assembly,
consisting of a sawtooth equipped aluminum extrusion,
provides deflection mechanism into the upper cutter
while simultaneously abrading thus weakening wire and
provides additional structural support for the upper cutter
mounting. The mechanical cutter assembly (upper and
lower) (figure 2-9) consists of a sawtooth equipped
deflector section, providing deflection/abrading feature
similar to the windshield deflector section, leading into
the primary wire cutting mechanism - wedge type cutting
blades positioned to provide the necessary mechanical
advantage to cut the design objective wires while
minimizing load input into the airframe. The lower cutter
assembly features a "Breakaway Tip" designed to shear
when relatively large ground contact forces are
experienced and before helicopter structural damage is
incurred. However, the tip shear rivets are designed to
withstand the smaller forces experienced during wire
strikes and the tip will still effectively deflect wires into the
cutter blades.
a. Wire Strikes. If avoidance is not possible or not
effective a wire strike will occur. The protection provided
by the WSPS is 90% of frontal area. The cable
impact/ deflection/ cutting sequence of the design
objective cables does not have a significant effect on
aircraft performance, control, crew functioning or blade
flapping.
b. Avoidance. The most effective defense against
wire strikes is avoidance. Because of the many different
encounters that can occur, it is not possible to provide a
procedure to cover every situation. The success in
coping with emergency depends on quick analysis of the
condition and selection of the proper evasive maneuvers
2-16
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