Figure 2-1-6. Canted Console (Typical)

TM 1-1520-240-10 2-1-9 2-1-21. Shoulder Harness Inertia Reel Lock Lever. A two-position shoulder harness inertia reel lock lever is on the left side of each seat (22, fig. 2-1-3) The lever positions are LOCKED (forward) and UNLOCKED (aft). The lock may be moved freely from one position to the other. When the lock lever is in UNLOCKED position, the reel harness cable is released to allow freedom of movement. However, the reel will automatically lock if a horizontal impact force of 2 to 3 g is encountered. When the reel is locked in this manner, it stays locked until the lock lever is moved forward to LOCKED and then returned to UNLOCKED. When the lever is at LOCKED, the reel is manually locked so the pilot is restrained from bending forward. When a crash landing or ditching is anticipated and time permits, manual locking of the shoulder harness inertia reel provides added safety be- yond the automatic feature of the inertia reel. Depending on the pilot’s seat adjustment, it may not be possible to reach all switches with the inertia locked. Each pilot should check and adjust the shoulder harness in locked position to deter- mine whether all switches can be reached. 2-1-22. Self -Tuning Dynamic Absorbers. The helicopter is equipped with three sel-tuning dynamic absorbers. One absorber is in the nose compartment and the other two absorbers are under each pilot’s seat below the cockpit floor. All three absorbers serve to maintain a minimum vibration level through the normal operating rotor RPM range of the helicopter. The self-tuning feature of the the dynamic absorber functions as follows: each dynamic absorber consists of tuning mass suspended by springs, and electronic measuring circuit, accelerome- ters, counter-weights, an electrical actuator and a self- test box. The accelerometers sense and compare the vibration phases of the helicopter and the spring- mounted mass. When the measured vibration phases differ from a built-in phase relationship required to assure proper tune, the electronic circuit extends or retracts the electrical actuator to reposition the counterweights which, in turn, increases or decreases the resonant fre- quency of the spring-mounted mass. The dynamic ab- sorbers are constantly being adjusted (tuned) to mini- mize helicopter vibration. A self-test box is in the heater compartment to provide maintenance personnel with an integral testing capability for self-tuning feature of the dynamic absorbers. Power is supplied by the No. 2 AC bus through the VIB ABSORB-LH, CTR and RH circuit breakers in the No. 2 PDP. Figure 2-1-6. Canted Console (Typical)