ATTITUDE INDICATING SYSTEM

The pilot attitude indicator, mounted in the instrument panel, displays flight attitude of helicopter relative to the earth. Pitch Attitude is indicated by up and down motion of the sphere with respect to horizontal reference. Roll attitude is indicated by rotational motion of roll pointer with respect to the fixed roll scale located at top of display. The indicator sphere can be adjusted to zero indication by the pitch trim knob which is located on face of instrument in lower right corner, and a roll trim control located on face in lower left corner on pilot indicator. The glideslope pointer displays helicopter deviation from the glideslope beam center or FM homing signal strength. The pointer represents position of beam center in relation to helicopter during glideslope operation. During FM homing operation, the pointer deflects downward with increased signal strength. The rate-of-turn pointer indicates in which direction and at what rate the helicopter is turning. The inclinometer ( ball ) indicates when the helicopter is in balance, either in a turn or in straight and level flight. If the helicopter is yawing or slipping, the ball will be off center. The ATT ( attitude ) warning flag provides visual indication of system malfunction. The warning flag comes into view whenever a malfunction occurs in the system circuit. The glideslope (GS) warning flag appears when glideslope signal is unreliably weak or when the GS receiver malfunctions if COURSE switch on HSI display control panel is positioned to VOR. If the course switch is in FM HOME position, the flag appears when the homing signal is unreliably weak or when the FM receiver malfunctions.