TM 1-1520-238-T-4
5–10
Change 10
5–6.
CONTROLS AND INDICATORS (cont)
5–6
Table 5–1.
Rotor System Controls And Indicators (cont)
Master Caution/Warning Panel
SWITCH/INDICATOR
POSITION
FUNCTION
HIGH RPM ROTOR
indicator
RED (ACV)
Lights when rotor speed is greater than 104%.
RED (ACW)
Lights when rotor speed is greater than 108%.
LOW RPM ROTOR
indicator
RED
Lights when rotor speed is less than 92%.
M58-194
LOW RPM ROTOR
INDICATOR
HIGH RPM ROTOR
INDICATOR
Master Caution/Warning Panel
SECTION II.
THEORY OF OPERATION
5–7.
SYSTEM DESCRIPTION
5–7
Rotor System.
The purpose of the rotor system (fig. 5–8) is to provide lift, thrust, directional flight, and
anti–torque control for the helicopter. The rotor system consists of the main rotor assembly, the tail rotor assembly,
and the controls and indicators used by the crew to operate the rotor system.
a. The main rotor assembly is secured to the top of the static mast so that it transfers the flight loads to the
static mast and then to the airframe. The main rotor head is a four arm, fully articulated assembly that provides
attachment points for the four main rotor blades. The main rotor blades attach to the rotor head by titanium
lead–lag links and steel blade attachment pins.
b. Each main rotor blade outboard end is swept aft 20 and the blade is equipped with a de–ice heater
blanket. A static discharger is mounted on the trailing edge at the point where the blade starts to sweep aft. The
main rotor blades are designed to prevent catastrophic failure in the event of certain kinds of battle damage and
cracks. The installed main rotor blades can also be folded into a special saddle for helicopter transportation or
storage.
c. The tail rotor head assembly is a two arm, teetering assembly that provides attachment points for the four
tail rotor blades. Flight loads are transferred from the tail rotor assembly to the static support and to the airframe.
Each tail rotor blade is attached to the tail rotor head by a pre–load indicating (PLI) washer, bolt and nut
combination.
