ROTOR BRAKE – GENERAL
The Rotor Brake (RB) is described in SECTION 5 – OPTIONAL
EQUIPMENT SUPPLEMENTS of the AW139–RFM–4D.
The Rotor Brake allows:
• a rapid deceleration of the rotors after engines shut down
• to maintain the rotors stopped up to 8 hours
• the manual restore of the parking pressure
ROTOR BARKE – MAIN COMPONENTS
ROTOR BRAKE CONTROL LEVER (RBCL)
The pilot manually operates the Rotor Brake Control Lever for the selection
of one of the following positions:
• OFF (RB release)
• PUMPING from forward detent and backward stop (pumping limit)
• BRAKE
The RBCL transmits mechanically the control to the Rotor Brake Control
Module (RBCM). The trigger with the spring lets the pilots to unlock the lever
and move it between the OFF and BRAKE position.
ROTOR BRAKE CONTROL MODULE (RBCM)
The Rotor Brake Control Module (RBCM) transforms the action of the pilot in
hydraulic power of the RB circuit. The RBCM includes:
• a dual-stage hydraulic pump that supplies the necessary pressure and
fluid displacement;
• an outlet valve which discharges the pressure in the hydraulic
reservoir;
• an hydraulic accumulator which provides the hydraulic fluid
displacement during the brake application;
• a shut-off valve which manages the RB circuit;
• an interlock pressure switch which detects the pressure in the circuit;
• a pressure transducer which provides monitoring of pressure values
and gives a visual indication on the RBPI.
ROTOR BRAKE PRESSURE INDICATOR (RBPI)
The Rotor Brake Pressure Indicator (RBPI) is installed inside the cockpit and
gives:
• rotor brake pressure indications (on the display),
• the position of the caliper.
ROTOR BRAKE ASSEMBLY (RBA)
The Rotor Brake Assembly (RBA) comprises the caliper, the pads and the
pistons.
The RBA provides for the braking action when pistons are hydraulically
actuated to clamp the rotating disc bolted to the tail output drive shaft flange.
ROTOR BRAKE ACTUATION ASSEMBLY (RBAA)
The Rotor Brake Actuation Assembly (RBAA) provides for to move and to
maintain the RBA caliper on its operative UP and DOWN positions.
ROTOR BRAKE RELAY BOX (RBRB)
The Rotor Brake Relay Box (RBRB) controls the UP and DOWN movements
of the caliper according to this logic:
• during flight the caliper is maintained in DOWN position far from the
rotor brake disc;
• on the ground with the engines OFF the caliper is moved in UP
position.
The electrical signals used for the braking action are provided by:
• the Rotor Brake Control Lever position;
• the Rotor Brake Actuation Assembly UP/DOWN position;
• the engine mode selector position;
• the Weight–On–Wheels (WOW) microswitch.