The auxiliary power unit drives the accessory drive section of the main transmission to provide full electrical, pneumatic,
and hydraulic power to-the helicopter when the main engines are not on line. The auxiliary power unit is also used to
provide pressurized air system air to start the main engines.
Flight controls are mechanically actuated, hydraulically powered, and electrically assisted in all flight control axes.
A curved canopy structure provides integral rollover protection. The canopy has a blast shield between the two crew
stations. Each crew station contains an adjustable armored seat. The seats incorporate armored wings which pivot to
facilitate entrance to, and exit from, the crew stations.
Configuration. The general configuration of the AH-64A helicopter is shown in Figure 1-2.
Airframe Stations. Fuselage stations, waterlines, buttlines, and centerlines provide an accurate method of
locating or installing parts and/or equipment in the airframe (Figure 1-3). All dimensions are in inches. Dimensions have
FS, WL, CL, or BL in front of the numbers.
Fuselage Stations. Fuselage stations (FS) are distances from a point in front of the helicopter nose. The first
station is zero (0.00).
Waterlines. Waterlines (WL) are distances from a point below the helicopter. They follow the centerline.
Centerline. Centerline (CL) is an imaginary line that passes through the center of the helicopter. The
centerline runs from the nose to the tail.
Buttlines. Buttlines (BL) are distances from the centerline. They start at the centerline and show the distance
to each side of the helicopter. Buttlines will be either to the left or right side.
These dimensions help you find any point on the helicopter. Each point shown on the following pages is a part of the
helicopter you can see.
1.2 TYPE OF CONSTRUCTION.
The following paragraphs describe the type of construction and materials used in the manufacture of the
major AH-64A helicopter components.
Rotor System. The rotor system interfaces with the drive system and flight controls system.
The rotor system provides lift, thrust, directional flight, and anti-torque control for the helicopter. The rotor system
includes the 'main rotor assembly, a single, four-bladed, 48-foot diameter main rotor that provides vertical, longitudinal,
and lateral flight capabilities; the tail rotor assembly, a single, four-bladed, nine-foot diameter teetering tail rotor that
provides anti-torque and directional flight capabilities; and controls and indicators, various cockpit-mounted controls and
indicators used by the aircrew for operating the rotor system. The controls and indicators provide indications of system
The main rotor assembly is secured to the upper portion of the static mast and main drive shaft. The main rotor head
assembly is a fully articulated assembly that provides attachment points for the four main rotor blade assemblies. The
main rotor head assembly provides the means to drive the main rotor blade assemblies in a counterclockwise rotation
while providing feathering, flapping, and lead-lag movement of each blade.