Robinsons R66 - 76-00 Description; 76-10 Fuel Control Unit (FCU)

CHAPTER 76
ENGINE CONTROLS
76-00 Description
A twist grip throttle control is located on each collective stick. The controls are interconnected
and actuate the Rolls-Royce engine model 250-C300/A1 fuel control input lever via a push-pull
cable. The throttle is normally not used for control but is set either fully closed (idle position)
or fully open.
The engine incorporates a hydromechanical governor which attempts to maintain 100% engine
output shaft RPM when the throttle is in the open position. A linkage provides the power
turbine governor with collective inputs to help anticipate changing power demands.
Large power changes or varying environmental conditions may cause the governor RPM setting
to vary by a few percent. A momentary toggle switch (beep switch) on the collective stick is
provided to trim, or "beep", the governor setting to the desired RPM. The switch controls an
actuator which adjusts the linkage between the collective and power turbine governor.
The governor controls RPM under normal conditions. It may not prevent over- or under-speed
conditions generated by aggressive ight maneuvers or rapid power changes.
Other engine controls include a push-pull fuel cutoff control on the console face, a start button
on the pilot's collective, a key-type igniter switch, and an anti-ice switch.
76-10 Fuel Control Unit (FCU)
Refer to R66 Illustrated Parts Catalog (IPC) Figure 76-1.
A. Removal
1. Pull fuel valve OFF. Remove engine cowling assembly per Section 53-21.
2. Refer to Figure 76-1. Remove fasteners securing C522-10 throttle and A522-10 fuel
cutoff control inner wires to FCU throttle and fuel cutoff levers.
3. Remove fasteners securing control housings and AN742-4 clamps to F577 bracket
assemblies, as required.
4. Remove FCU per RR300 Series Operation and Maintenance Manual (OMM).
5. If sending FCU to repair facility, remove F147-1 (minimum throttle stop) screw and
D930-2 spring.
B. Installation
1. If removed: Install F147-1 (minimum throttle stop) screw, special torque screw per
Section 20-33, and torque stripe per Figure 5-1. Install D930-2 spring.
2. Install FCU per RR300 Series Operation and Maintenance Manual (OMM).
3. Perform throttle control rigging per Section 76-11.
4. Perform fuel cutoff control rigging per Section 76-12.
5. Push fuel valve ON.
SEP 2012 R66 Maintenance Manual Chapter 76 Engine Controls Page 76.1