R44-II POH Section 7 (Systems) Flashcards
Describe the Powerplant on the R44.
Lycoming IO-540 six-cylinder, horizontally opposed, overhead-valve, air-cooled, fuel-injected engine with a wet sump oil system. Equipped with a starter, alternator, shielded ignition, two magnetos, muffler, two oil coolers, oil filter, and induction air filter.
Displacement: 541.5 cubic inches
Max continuous rating: 205 BHP at 2718 RPM (102% on tach)
5 min takeoff rating: 245 BHP at 2718 RPM
Limitations:
Max continuous speed: 102% (2718 RPM)
Max transient speed: 105% (2800 RPM)
Cylinder Head Max Temp: 500F (260C)
Oil Max Temp: 245F (118C)
Oil Pressure min during idle: 25 psi
Oil Pressure min during flight: 55 psi
Oil Pressure Max during flight: 95 psi
Oil Pressure Max during start & warm up: 115 psi
Minimum oil quantity for takeoff: 7qt
Max oil quantity for takeoff: 9qt
Describe The Drive/Clutch System on the R44.
A vee-belt sheave is bolted directly to the engine output shaft. Vee-belts transmit power to the upper sheave which has an overrunning clutch contained in it’s hub. The inner shaft of the clutch transmits power forward to the main rotor and aft to the tail rotor. Flexible couplings are located at the main gearbox input and at each end of the long tail rotor drive shaft. The main gearbox contains a single-stage spiral-bevel gear set which is splash lubricated. The tail gearbox contains a single 90 degree splash-lubricated spiral-bevel gear set.
After the engine is started, it is coupled to the rotor drive system through the vee-belts which are tensioned by raising the upper drive sheave. An electric actuator, located between the drive sheaves, raises the upper sheave when the pilot engages the clutch switch. The actuator senses compressive load and switches off when the vee-belts are properly tensioned. The clutch caution light illuminates whenever the actuator circuit is energized. the light stays on until the belts are properly tensioned or fully disengaged.
A fuse on the test switch panel prevents an actuator motor overload from tripping the clutch circuit breaker. If the fuse blows, the actuator motor will stop but the clutch caution light will remain illuminated. An open circuit breaker removes power from both the motor and the light.
Describe the Electrical System on the R44.
A 28-volt DC electrical system including an alternator and a sealed lead-acid battery is standard.
A circuit breaker panel is located on the ledge just forward of the left front seat. In flight reset of circuit breakers is not recommended.
A 14V alternator powered by the engine provides electricity when the engine is running, and charges the 12V battery. If the alternator fails the battery acts as a backup but only for 10min or less. If ALT caution light comes on in flight, land as soon as practical.
The 12V battery is needed for backup, initial startup power, and to help protect electrical equipment from voltage spikes.
If electrical power fails, that includes the tachs, governor, low RPM warning system, radios, lights, fuel gauge, etc. The magnetos keep the engine running, converting mechanical energy into electrical energy. Each one provides spark to all four cylinders.
Engine and rotor tachs, governor, and low RPM are on separate circuits. These can still be powered if battery is healthy but switch is off, via a wire bypass fuse near the battery.
Describe the Fuel System on the R44.
Consists of a main (29.5 usable) and an auxiliary tank (17 usable), a shutoff valve control located between the front seats, a strainer (gascolator) , an engine-driven pump, and an auxiliary (electric) pump. The fuel tanks have flexible bladders in aluminum enclosures. A fuel return line allows pump supply in excess of engine demand to return to the fuel tanks.
The auxiliary pump primes the engine for starting and runs in flight to provide fuel pump redundancy.
Fuel gauges are electrically operated by float-type transmitters in the tanks. When gauges read E, the tanks are empty except for a small quantity of unusable fuel. The low fuel caution light is actuated by a separate electric sender located on the bottom of the main tank.
The auxiliary tank is interconnected with the main tank and located somewhat higher so it will become empty first while fuel still remains in the main tank.
Approved fuel grades are shown here.
Fuel burn rate is ~15gpm
Describe the Engine RPM Controls on the R44.
Throttle: Twist grip, mechanically linked to throttle valve
Correlator: mechanically links the throttle to collective inputs
Governor: the governor maintains engine RPM by sensing change and applying corrective throttle inputs through a friction clutch which can be easily overriden by the pilot. The governor is active only above 80% engine RPM and can be switched on or off using the toggle switch on the end of the right seat collective. It may not prevent over- or under-speed conditions generated by aggressive flight maneuvers. Above 6000’, throttle-collective correlation and governor are less effective; power changes should be slow and smooth
Describe R44 main rotor system.
- Semi-rigid system with two all-metal blades mounted to the hub by coning hinges. The hub is mounted to the shaft by a teeter hinge which allows for blade flapping. Both hinges use self-lubricated bearings
- Droop stops for the blades provide teeter hinge friction which normally prevents the rotor from teetering while starting/stoping
- Pitch change bearings are enclosed in a housing at the blade root, which is filled with oil and sealed with an elastomeric boot
- Each blade is a thick stainless steel spar at the leading edge; the skins are bonded to the spar approximately 1” aft of the leading edge
- The blades have a 10” inboard chord and 10.6” outboard chord with a blade twist of -6 degrees
- rotor disk diameter of 33’
POH 7-2, 1-4
Describe the R44 tail rotor system.
- Two all-metal blades attached to a teetering hub with a fixed coning angle and a blade chord of 5.1 inches (constant)
- The pitch change bearings have self-lubricated liners
- The teetering hinge bearings are elastomeric
- rotor disk diameter of 4’ 10”
POH 7-2, 1-4
Describe the R44 flight controls.
Dual controls are standard and all primary controls are actuated through push-pull tubes and bellcranks. Bearings are all either sealed or have self-lubricating liners
Describe the R44 hydraulic system.
Hydraulically-boosted main rotor flight controls eliminate cyclic and collective feedback forces.
- The pump is mounted on and driven by the main gearbox
- A servo is connected to each of the three push-pull tubes that support the main rotor swashplate
- The reservoir is mounted on the steel tube frame behind the main gearbox and includes a filter, pressure relief valve, and pilot-controlled pressure shut-off valve which is solenoid-actuated and controlled by the hydraulic switch on the cyclic
- The working fluid is MIL-H_5606 and normal operating pressure us 450-500 PSI
- A sight gauge for fluid level checks is incorporated into the reservoir; a vented filler cap is located on top
