BV107-II Systems Flashcards
SYSTEM MALFUNCTIONS
You notice your Aft Transmission Pressure has dropped and your NR indication has dropped to zero. What has happened? What procedure would you apply?
Your Aft Transmission may be failing.
Carry out procedure for imminent transmission failure. (Nr tach generator reads from the Aft Transmission)
ENGINE CONTROL
What do the positions of the ECL’s do?
Stop - fuel shut off and ignition disabled
Crank - fuel shut off, ignition system energized and the starter remains engaged until starter cutout at 46%ng or ECL is brought back to stop
Start - fuel is provided and fuel control is allowed to automatically start the engine. At ground idle the fuel control will govern to hold NG stable
Fly - fuel control is governing NF
ELECTRICAL SYSTEM
What does the MASTER BATTERY switch do?
1) Completes the circuit between the BATT switch and main battery relay.
2) Ground to the AUX BATT switch.
3) Ground for the AC frequency control relays.
4) Closes the DC external power relay
ELECTRICAL SYSTEM
What does the BATTERY switch do?
ON position closes the battery relay and the battery is connected to the DC bus.
OFF position power is interrupted to the relay and the battery is disconnected from the DC bus.
ELECTRICAL SYSTEM
What does the INVERTER switch do?
DC voltage is supplied to the inverter from the DC bus. The inverter then delivers single-phase 115 VAC, 400 Hz power to the SAS and the two phase-B instrument buses. (Used to power instruments during DC start up or when no AC power is available)
SYSTEM MALFUCNTIONS
When loss of NG indication occurs what other system should you monitor for indications of a greater problem?
Engine oil pressure, the NG tach generator is powered by the accessory drive at the engine oil pump.
ELECTRICAL SYSTEM
What does the AC bus feed switch do?
Used to switch to auxiliary AC feeders if there is a malfunction in the normal feeder lines.
Used to select either GEN as the primary AC power source.
NORM position with both GEN’s on, number 1 is primary and 2 is in stand by. Opposite for AUX position.
ELECTRICAL SYSTEM
What do the Transformer Rectifiers do?
Rectify 115/208 VAC into 28 VDC power for the DC system. When switched to the ON position they are connected to the DC bus, disconnected when moved to the OFF position.
ELECTRICAL SYSTEM
What do the GENERATOR switches do?
Applies voltage to the field energizing the GEN and the output is then connected to the bus.
ELECTRICAL SYSTEM
What does an illuminated AC Feeder Fail warning light mean?
Fault is detected in the selected feeder. Manually switch to the feeder not in use.
ELECTRICAL SYSTEM
Describe the GENERATOR’s
20 KVA Generators
115/208 VAC
Three-Phase
380-420 Hz
ELECTRICAL SYSTEM
Are both GENERATOR’s connected to the electrical system?
No, one unit is in
stand-by mode.
ELECTRICAL SYSTEM
What is the purpose of the GCU’s?
1) Detect over voltage
2) Detect under voltage
3) Detect under frequency
4) Remove the faulty GEN from the bus when one of these conditions is detected.
ELECTRICAL SYSTEM
What do the Differential Protection Units do?
Associated with each GEN
1) Detects current differential between the three phases.
2) Opens the field circuit to disable the generator when imbalance is detected.
3) Activate change over circuitry causing the appropriate GEN to accept the electrical load.
SYSTEM MALFUNCTIONS
If you have a full electrical failure can you still shut down the engines?
Yes, you can attempt to use the 24volt AUX battery to move the ECA to STOP or START then trim the engine down to shutdown, or manually close the fuel shut off valves located in the stub wings.
ELECTRICAL SYSTEM
What are the frequency control relays?
Located under the ECL’s on the center console.
1) Prevent generator operation before the ECL’s are placed in FLY.
2) If the NR falls below 83% when in FLY the under frequency cutout is delayed 10 seconds.
3) The relays also open the rotor brake circuits so the brake cannot be engaged with the ECL’s in FLY.
FUEL SYSTEM
When will the FUEL BOOST FAIL lights illuminate?
When pressure output drops to 10 +/- 3 PSI on either of the two boost pumps located in the stub wings a pressure switch will illuminate the associated light.
FUEL SYSTEM
When does the LOW FUEL PRESS warning light illuminate?
When inlet fuel pressure drops to 7.5 +/- 0.5 PSI a pressure switch located in the engine compartment will illuminate the associated light.
(This light will illuminate above 10,000’ if the boost pump is not operating)
FUEL SYSTEM
Are the fuel boost pumps powered by DC or AC power?
175 gallon tanks use 28 VDC to power the boost pumps.
190 gallon tanks use 115 VAC three phase to power the pumps.
Both variations utilize 28 VDC control
HYDRAULIC SYSTEM
Describe the components of the hydraulic system.
Two independent systems No. 1 and No. 2
Pressure compensated variable delivery pumps driven by the FWD XMSN
Hydraulic reservoir (side by side tanks, shared vent and overboard drain line)
Low fluid level switches
Two pressure switches (1 per system)
Four pressure filters (2 per system)
Two return filters (1 per system)
Two case drain filters (1 per system)
Two pressure transmitters and indicators
Stick boost manifolds
Lower stick boost actuators
Upper stick boost actuators
SAS extensible links
SAS control valves
Accumulators
HYDRAULIC SYSTEM
SAS components and operation
The Stability Augmentation System (SAS) is an electro-hydraulic system that assists the pilot in maintaining helicopter stability about the pitch, roll, and yaw axes.
The SAS responds to changes in attitude as sensed by rate gyros.
Rate-of-motion signals created by rate gyros are processed then sent to the extensible links in the appropriate axis where they are converted into flight control movements.
These inputs are not felt in the controls as the extensible links are located after the lower stick boost actuators.
The systems primary reference is the rate of motion in the given axis and not the actual aircraft attitude.
The SAS has limited control authority (15% in pitch and roll, and 33% in yaw).
Components include: Extensible links LVDT’s Amplifiers Rate Gyros Control Valves SAS on/off selector Pedal Potentiometer Side Slip Ports Pitot static lines
HYDRAULIC SYSTEM
Describe the flow of HYD fluid through the system
Reservoir Quick disconnect Pump Suction to Pump (Case Drain HYD fluid routed to Case Drain filters then to return lines prior to return filters) Pump Pressure to reservoir Pressure Relief Valve internal in Reservoir Quick disconnect Pressure Switch (half gain relay) Upper Pressure Filters Upper Boost System (T-off routes down to lower boost system) Accumulators Direct pressure gauges Lower pressure filters SAS control valves and SAS if activated Snubbers HYD Pressure transmitters Lower boost system manifolds to LDBA’s
Return lines routed to return filters then to reservoir.
ENGINE
Describe the fuel control
Hydromechanical computer
Driven by the accessory drive
Uses the following signal inputs AM, P3, T2, NG, and NF.
Schedules the correct fuel/air flow during start
Governs Ng speed at idle
Maintains a constant Nf speed in FLY
Prevents compressor and power turbine overspeed, compressor stalls, over temperature, and rich/lean blowouts by sensing the onset of these conditions and computing a reaction by adjusting fuel pressure.
Uses raw fuel pressure as a hydraulic force to operate the stator vane actuator.
