The UH-1C / UH-1M is a utility type helicopter. The helicopter has a two-bladed, semi-rigid main rotor.The fuselage consists of two main sections, the forward section and the aft or tailboom section. Seating positions may be in a two to eleven place arrangement, with the pilot in the forward right-hand location. Conversion from passenger to cargo configuration may be accomplished by removal of the seats. The airframe has built- in work platforms and cowling that can be opened or removed for access to all major components.

Tailboom section.

The tailboom section, attached to the forward fuselage by four bolts, is a tapered semimonocoque structure with a vertical fin slanting up and aft at the rear end to support the tail rotor. Tail rotor driveshafts and gearboxes are mounted under covers along the top of the tailboom and front of the vertical fin. A controllable elevator is also mounted on the tailboom.

Propulsion System.

The propulsion system consists of a gas turbine engine, main driveshaft, transmission and mast, main rotor, and the tail rotor with it's driveshafts and gearboxes. The engine drives the transmission through the short main driveshaft, rotating the mast and main rotor. Power is also taken off from the transmission to drive the tail rotor. Fuel tanks consist of two interconnected cells, Fig.1 & Fig.2 located in the forward fuselage.

T53-L-13B gas turbine engine

Engine Anti-Ice System

T53 Variable Inlet Guide Vane Actuator

Main Driveshaft [ exploded parts view ] Fig.1 | Fig.2 | Fig.3

Main Rotor [ exploded parts view ] Fig.1 | Fig.2 | Fig.3 | Fig.4 | Fig.5 | Fig.6

Main Rotor Blade Description. [ B540 ] The main rotor blades are metal, bonded assemblies. Each blade is attached in the hub with a retaining bolt assembly and is held in alignment by adjustable drag braces.

Main Transmission and Mast [ exploded parts view ] Fig.1 | Fig.2 | Fig.3 | Fig.4 | Fig.5 | Fig.6 | Fig.7 | Fig.8

Upper pylon assembly [ exploded parts view ]

Lower pylon assembly [ exploded parts view ]

Stabilizer Bar [ exploded parts view ]

Dynamic Stop [ exploded parts view ]

Damper Assembly [ exploded part view ]

Swashplate and Support Assembly [ exploded parts view ] Fig.1 | Fig.2

Tail Rotor [ exploded parts view ] Fig. 1 | Fig. 2

Tail Rotor Drive Shaft [ exploded parts view ] Fig. 1

Tail Rotor Driveshaft Hanger Bearing [ exploded parts view ] Fig.1

42 Degree Intermediate Gearbox [ exploded parts view ]

90 Degree Tail Rotor Gearbox [ exploded parts view ]

Flight Control System Description.

The flight control system consists of the collective pitch control system, cyclic control system (pitch and roll) elevator control system tail rotor (directional) control system. The flight control systems are mechanical linkages, actuated by conventional controls, and are used to control flight attitude and direction. The flight controls systems are a straight through system with hydraulic boost. A synchronized elevator is linked into the fore and aft control system at the swashplate. Electrically operated force trims, connected to cyclic and tail rotor controls, induce artificial feel and stabilize control stick and tail rotor control pedals.

Collective Control System Description.

The collective control system consists of a jackshaft assembly with dual control sticks, push pull tubes and bellcranks, and a hydraulic actuator connected to a collective lever on a swashplate assembly. Movement of either control stick is transmitted through linkage and hydraulic actuator to main rotor pitch control mechanism, causing helicopter to ascend or to remain at constant altitude. The collective hydraulic actuator has an irreversible valve to reduce feedback forces.

Elevator Control System Description.

The synchronized elevator is located near the aft end of the tail boom and is connected by control tubes, bellcranks and mechanical linkage to the fore and aft cyclic control system. Fore and aft movement of the cyclic control stick produces a change in the synchronized elevator attitude, thus increasing controllability of the helicopter. Fig.1 | Fig.2 | Fig. 3 | Fig. 4

Cyclic Control System [ exploded parts view ] Description. A system of linkage transmits movement from cyclic control sticks to the swashplate which actuates rotating controls to the main rotor, controlling the direction of helicopter. Fore-aft lateral control are independent linkages from the control stick to an intermixing bellcrank. From this point on the swashplate horns, linkage cannot be considered separately as to effect. Two hydraulic power cylinders are incorporated to reduce effort required for control and to reduce feedback forces from main rotor. Two force gradient units, with magnetic brakes, are incorporated for artificial control feed and stabilization of controls.

Tail Rotor Control System [ exploded parts view ] Description. The tail rotor system includes control pedals, pedal adjusters, a force gradient (centering spring ) assembly with an electrically operated magnetic brake, hydraulic actuator, a quadrant, cables and control mechanism mounted through the tail rotor shaft, and connecting linkage. Actuation of pedals causes power-assisted pitch change of tail rotor blades to offset mail rotor torque and control directional heading of helicopter. Fig. 1 | Fig. 2 | Fig. 3 | Fig. 4

The helicopter has two electrical power systems, direct current and alternating current. The basic power supply is a 28 Vdc, single-conductor system using helicopter structure as negative ground. Power for the dc system is provided by either the main generator, standby starter-generation, battery, or external power. Emergency dc power is provided by the standby starter-generator, which is mounted on the engine. Alternating current is supplied by two 250-volt-ampere, 3-phase inverters (main and spare) that convert 28Vdc to 115 Vac. The inverters are identical, and either is capable of supplying the power required for operation of the ac-operated equipment.

The helicopters landing gear is a skid-type gear. Two ground handling gear wheel assemblies (provided in the loose equipment) may be attached to permanently installed fittings on the skid gear to facilitate ground handling. A tubular steel tail skid is attached to the lower aft section of the tailboom to protect the tail rotor in case of a tail-low landing.