Aircraft Systems Flashcards
What are the 4 sections of the engine?
Cold Section
Hot Section
Power Turbine Section
Accessory (Gearbox) Section
What are the functions of the HMU?
PM CAN VDTO
Pumps fuel at a high pressure (400-832 psi, 300 psi idle) for better atomization.
Meters fuel via the LDS, PAS, and DEC (Torque Motor) inputs.
Collective pitch compensation through the LDS. When collective is moved, NG is reset for immediate NP response.
Accel/decel fuel flow limiting to prevent compressor stalls, engine damage, and flameout.
NG limiting (will occur before TGT limiting in extreme cold weather) and NG shutdown (at 110% NG).
Variable Geometry Positioning of the inlet guide vanes for optimum performance.
DEC Lockout via the PAS to bypass torque motor inputs from the DEC.
Torque Motor input to trim NG output.
Opens the vapor vent for fuel priming.
What are the functions of the ODV?
HOPS
Hot start prevention (shuts off fuel when activated by hot start preventer).
Overspeed Protection (limits fuel flow when signal is sent from DEC).
Purges main fuel manifold and nozzles at shutdown to prevent coking.
Sequencing of main fuel for engine starting and operation.
What are the 3 windings in the alternator?
NIP
NG signal to the cockpit (green)
Ignition power to the exciters during start (black)
Power for DEC (yellow)
What happens during a complete alternator failure?
Loss of NG cockpit indication with corresponding ENG OUT warnings and audio (NG < 55%). NOTE: There will be no loss of NP1 and NP2, or Q, and Overspeed Protection is still available due to DEC being backed up by airframe power.
What are the functions of the DEC?
FT (TINT) HHOT
Fault Indication through the TQ indicator.
Trims HMU output through the torque motor based on:
- TGT limiting at 897+/-9 Dual Engine or 903+/-10 when other engine is below 50% Q (DEC, sooner with EDECU).
- Isochronous NP Governing to maintain NP at the reference set by the pilot.
- NP reference from the cockpit via the Eng Speed Trim Switch (INCR/DECR) from 96-100%
- Torque matching/Load sharing increases power on the low engine up to 3% above the reference.
Hot Start Preventer tells ODV to shutoff fuel when TGT 900 degrees Celsius, NG<60%, NP<50%.
History Counter Signal.
Overspeed Protection at 120%+/-1%.
Transient Droop Compensation. 4-1 improvement to reduce transient droop.
When does the EDECU switch from the 10-minute TGT limiting value to the higher 2.5-minute TGT limiting value?
When any of the following occur:
1) NP drops below 96%
2) Greater than 3% droop between reference NP and actual NP
3) Greater than 5% per second NP droop rate exists and NP less than or equal to NP reference.
What functions are locked out when going to (DEC) lockout?
1) TGT limiting
2) Isochronous NP Governing
3) NP reference from the cockpit
4) Torque Matching/Load Sharing
If an engine fails to the highside (DEC failure) will the other engine RPM rise with it? For how long?
Yes, but only until NP is 3% above the reference NP.
In what 3 (emergency) situations will TGT limiting not work?
Engine starts, compressor stall, lockout
Is the TGT temp displayed in the aircraft the actual temperature of the engine? Why?
No, it has a -112 degree C bias (the engine is running hotter than the indication).
What parameters will activate HSP? Can it be overridden?
TGT>900 C, NG<60%, and NP<50%
It can be disabled for emergency starts by pressing and holding the overspeed test button (TEST A/B) for the engine being started during the start sequence.
What is the main function of the MMU?
Minimize inherent control coupling. (Basically, decreased pilot workload).
What are the 4 types of mixing the MMU provides, what do they compensate for, and what input does it provide?
- Collective to Pitch: Compensates for the rotor downwash on the stabilator. Provides forward input to the rotor as collective is increased and aft as it is decreased.
- Collective to Roll: Compensates for translating tendency. Provides left input to rotor as collective is increased, right as it is decreased.
- Collective to Yaw: Compensates for torque effect. Increases TR pitch as collective is increased, and decreases TR pitch as collective is decreased.
- Yaw to Pitch: Compensates for the vertical thrust component of the canted TR. Provides aft input rotor as TR pitch is increased, and forward as TR pitch is decreased.
What is electronic coupling? What does it compensate for?
Collective/Airspeed to Yaw - helps compensate for the torque effect. Decreases TR pitch as airspeed increases and TR and cambered fin become more efficient. Maximum mixing occurs from 0-40 knots, then decreases to 100 knots, after which no mixing occurs.
What controls electronic coupling (what is it a function of?)
2 FCC
What are the speeds associated with electronic coupling?
- 0-40 knots: Maximum mixing
- 40-100 knots - Mixing decreases
>100 knots: No mixing
What are the 5 subsystems of AFCS?
1) SAS
2) Trim
3) FPS
4) Coupled Flight Director
5) Stabilator
What is the central component to the AFCS system (where the AFCS systems gain their information/signals to operate)?
1 and #2 Flight Control Computers (FCC)
Which FCC is the only FCC that sends signals to the trim actuators?
The #2 FCC
How does each FCC know the status of the other?
The Cross Channel Data Link (CCDL)
Airspeed, Barometric Altitude, and Barometric Rate are provided to the FCCs through which system?
Air Data Computers
The primary function of the _____ is to compute attitude, heading, present position, and turn rate.
EGI
What are the inner loop and outer loop systems in the FCCs?
Inner loop - SAS
Outer loop - Trim
What are some of the characteristics of the inner loop of the FCCs?
Fast in response, limited in authority, does not move the flight controls.
How much control authority does the outer loop of the FCCs have and at what rate?
100% at a rate of 10% per second.
What are static and dynamic stability?
Static stability is long term and is the tendency to return to the pilot’s desired heading, attitude, or airspeed.
Dynamic Stability is short term and is the tendency to resist movement.
What does SAS provide? in what axes? What type of stability does it provide (dynamic/static)?
SAS enhances dynamic stability by providing short term rate dampening in the pitch, roll, and yaw axis.
What are the brains of SAS1? SAS2?
SAS 1 - #1 FCC
SAS 2 - #2 FCC
What is the muscle for SAS?
Pitch, Roll, and Yaw SAS Actuators
How much control authority does SAS have? What if one SAS fails?
5% each for a total of 10%. If one SAS fails, the other will double its gain, but only to its max of 5% control authority.
When will the SAS OFF caution appear?
Loss of actuator pressure, or if both SAS1 and SAS2 are turned off.
How is a SAS malfunction identified?
Erratic motion in the helicopter.
What axes (motions) does Trim work in?
Pitch, Roll, Yaw, Collective
What is the muscle for Trim?
3 Trim Actuators (Roll, Yaw, Collective), and 1 Trim Servo (pitch).
What system monitors Trim?
2 FCC
What must be on for Trim to be fully operational (because of yaw trim)?
SAS/BOOST
What are the 3 functions of Trim?
Force Gradient, Muscle for FPS, and Electronic Coupling
If a Trim actuator becomes jammed, what allows the controls to still be moved? What force is required?
Slip clutches allow the flight controls to be moved if an actuator becomes jammed. It requires 80 lbs maximum in Yaw, 13 lbs maximum in Roll, and 22 lbs maximum in collective.
What type of actuators are used for pitch, roll, yaw, and collective trim?
Pitch - Electrohydromechanical actuator.
Roll, Yaw, Collective - Electromechanical actuators.
What does FPS provide? In what axes? What type of stability does it provide (dynamic/static)?
It provides a basic autopilot function in the Pitch, Roll, and Yaw axis. Provides long term static stability.
When coupled with trim, how much control authority does FPS have?
100%
What systems must be on for FPS to work?
SAS/BOOST, Trim, SAS 1 and/or SAS2. Stabilator is not required, performance will increase when operated in the auto mode.
What basic autopilot functions does FPS provide below 50 kts? Above 50 kts?
Below 50 kts:
Pitch: Attitude Hold
Roll: Attitude Hold
Yaw: Heading Hold
Above 50 kts:
Pitch: Airspeed/Attitude Hold
Roll: Attitude Hold
Yaw: Heading Hold or Turn Coordination
What are the brains for FPS? Muscle?
Brains - FCCs
Muscle - Trim Actuators
When/How is turn coordination activated?
When roll attitude is greater than 1 degree for any of the following:
1) Lateral cyclic greater than 1/3 inch stick displacement from trim.
2) Cyclic TRIM REL is pressed.
3) Roll attitude is beeped beyond 2.5 degrees bank angle.
What is the purpose of the stabilator?
Enhance the handling qualities of the helicopter and improves static and dynamic stability about the pitch axis.
What are the 5 functions of the Stabilator?
SCALP
Streamlines w/rotor downwash at low airspeeds (below 30 knots) to minimize nose up attitude.
Collective Coupling to minimize pitch attitude excursions due to collective inputs.
Angle of Incidence decreases above 30 knots to improve static stability.
Lateral Sideslip to Pitch coupling to reduce susceptibility to gusts. Stabilator goes up for nose right, and down for nose left.
Pitch Rate Feedback to improve dynamic stability. Dampens pitch excursions due to turbulence or “G” forces.
What are the brains for the Stabilator? Muscle?
Brains - 2 FCCs.
Muscle - 2 Stabilator Actuators.
On the MFD, What does it mean when the stabilator indicator is white, yellow, and red?
White: AUTO MODE
Yellow: MANUAL MODE
Red: When stabilator fail flag is displayed
What is the purposed of the Flight Director?
Provide autopilot functions
The steering commands derived from the navigation and flight instruments allow FPS to perform what tasks with a coupled Flight Director?
MMMAAA
Maintain a desired heading
Maintain fixed altitude and/or airspeed
Make a programmed accel/decel and climb/descent to a predetermined airspeed or altitude
Acquire a selected course
Acquire and track localizer and glide slope for ILS approach
Acquire and track an MFS route
What are the FD/DCP engagement parameters for the IAS (airspeed hold) mode?
50-150 KIAS
What are the FD/DCP engagement parameters for the HDG (heading hold) mode?
Above 50 KIAS
What are the FD/DCP engagement parameters for the ALT (barometric altitude hold) mode?
Above 50 KIAS
What are the FD/DCP engagement parameters for the RALT (radar altitude hold) mode?
0-1500 ft AGL
What are the FD/DCP engagement parameters for the VS (vertical speed hold) mode?
0-2000 fpm AND above 50 KIAS
What are the FD/DCP engagement parameters for the GA (go around) mode, and what will it provide?
Any airspeed or hover
Gives: 70 KIAS, 750 FPM climb.
What are the FD/DCP engagement parameters for the ALTP (altitude pre-select) mode?
Can be armed in flight or on the ground (will capture within 300’)
What are the FD/DCP engagement parameters for the FMS Navigation mode, and what will it provide?
Above 50 KIAS:
Provides roll command to follow the FMS flight plan.
What are the FD/DCP engagement parameters for the VOR, LOC, and GS Navigation modes, and what will it provide?
Above 50 KIAS:
VOR and LOC modes provide roll commands for the desired course, and GS mode provides collective commands to follow the glide slope.
What does the DECL (ILS Deceleration) mode provide when activated?
Pitch command to slow the helicopter to 70 KIAS by 200’ AGL using the DECL mode (0.5 kts per second deceleration).
What are the 3 different HVR modes that can be activated with the coupled Flight Director?
HVR DECL (deceleration mode) HVR VHLD (velocity hold) HVR POSN (position hold)
At what airspeed can HVR HOLD modes be engaged?
Below 60 knots
What HVR mode is engaged when pressing the “Z-axis plunge” on the trim beeper below 60 knots, and what other hold mode will be engaged (below 1500’ AGL)?
HVR DECL will be engaged along with RALT hold below 1500’ AGL.
When HVR DECL is activated through the z-axis plunge, what will the DECL mode do, and can the rate be changed?
The helicopter will be slowed at 2.5 knots per second, and the lateral velocity will be kept at 0. The helicopter will continue to slow until it is below 1 knot and HVR POSN will be engaged. The deceleration rate can be adjusted from 1.5 to 3.5 knots per second by pushing forward or aft on the cyclic trim beeper.
How can HVR VHLD be engaged?
By pressing the HVR hold button on the FD/DCP between 1-60 knots, or by pressing the cyclic TRIM REL button while in HVR DECL mode. Also, if in HVR POSN and the TRIM beeper switch is held for more than 1 second, HVR VHLD will be engaged.
What will HVR VHLD maintain while engaged?
The longitudinal and lateral velocity references at the reference ground speed at the time of engagement (lateral and longitudinal speed).
What happens if you press the TRIM REL button while in HVR VHLD mode? Cyclic Trim Beeper?
If the TRIM REL button is pressed, HVR VHLD will be disengaged and when the TRIM REL button is released, it will re-capture at the current longitudinal and lateral velocities. If the cyclic TRIM beeper is pressed, it will increase/decrease the VHLD velocity at a rate of 3.5 knots per second.
What are the maximum ground speeds forward, aft, and laterally in HVR VHLD?
Forward: 50 knots
Aft: 20 knots
Laterally: 20 knots
How can HVR POSN mode be activated?
It will automatically capture when either HVR VHLD or HVR DECL modes are engaged and the helicopter velocity drops below 1 knot GS.
When in HVR POSN mode, and the cyclic TRIM beeper is pressed, what will happen?
If less than one second, the POSN reference will be adjusted by 1-2 feet in that direction. If more than one second, HVR VHLD will be engaged.
When in HVR POSN mode, will pressing against the cyclic without pressing the cyclic TRIM REL switch change the hover reference point?
As long as ground speed does not exceed 2 knots, it will not be affected. Above 2 knots, DECL mode will engage and POSN will re-engage over the new position.
What will happen if you z-axis plunge above 60 knots?
Unusual attitude recover mode will be engaged. It will:
- Engage barometric altitude hold
- Level the wings (within the limitations of the trim system)
- Engage IAS hold at:
- 80 knots (between 80-120 knots)
- Current speed (between 80-120 knots)
- 120 knots (above 120 knots)
Below 50 knots, what will the collective trim beeper do?
Left/Right - Pedal turn of approximately 3 degrees per second. Once released, maintains heading.
Up/Down - Will adjust the reference altitude for collective FD functions. Once released, altitude hold (if previously engaged) is re-engaged at the new altitude.
Above 50 knots, what will the collective trim beeper do (if heading mode is not engaged)?
Left/Right - Standard rate turn until released, then back to wings level (previously set attitude).
Up/Down - Will adjust the reference altitude for collective FD functions. Once released, altitude hold (if previously engaged) is re-engaged at the new altitude.
The collective AFCS Trim Button is deactivated any time the heading hold mode is engaged.
What are the 5 transmission modules?
2 input modules
The main module
2 accessory modules
What is the tilt in the main transmission?
3 degree forward tilt
Where are the freewheeling units located?
The input modules
What is mounted on the accessory modules?
A main generator and a hydraulic pump
What sensor is located on the #2 accessory module?
Rotor speed. (There is also one on the #1 accessory module in the A+ and L models for transient droop response.
What switch is located on the #1 accessory module?
Oil Pressure Switch (Light at 14 PSI +/- 2)
How long can the gearboxes run without oil?
30 minutes
If the APU generator is the sole source of power, what limitations exist (with the systems)?
The windshield anti-ice and backup pump cannot be used simultaneously.
Why shouldn’t ice be allowed to accumulate on the windshield?
Ice shedding can cause engine FOD
What is the purpose of the OAT sensor?
Provides a signal to the controller for heating EOT (element on time) of the rotor blades. The lower the OAT, the longer the EOT will be.
How many IR sensors are located on the helicopter for fire detection?
5, 2 in each engine compartment and 1 in the APU compartment.
What happens when the APU Fire T-Handle is pulled?
1) Shuts off fuel to the APU
2) Sends a stop signal to the ESU (turning off the ignition to the APU)
3) The directional valve is armed for the APU compartment
Where does the extinguishing agent go if more than one lever is pulled?
The LAST lever pulled.
When does the crash activated fire extinguishing system activate? Where does the fire extinguishing agent go?
10 Gs or more. Both engine compartments.
What bottle must be discharged if there is no AC power to the helicopter?
The reserve
What firefighting capability is lost when there is no AC power to the helicopter?
No 2 Engine
What is AVCS (what is its purpose)?
Active Vibration Control System - reduces vibrations by mechanically generating additional vibrations out of phase with the main rotor in the 90-105 range. It compensates for changes in helicopter configurations throughout flight such as weight and CG.
What is the muscle for AVCS?
3 Force Generators (FGs)
What does each FG contain to produce force?
2 Mechanical Units (MUs)
How much is max torque decreased with the heater on?
5% (7.5% with Auxiliary Cabin Heater)
When will the heater automatically disengage?
During engine starts, and when it reaches 90 to 96 degrees Celsius
What are the minimum parking requirements?
1) Rotor brake or gust lock engaged
2) Wheel brakes set
3) Tailwheel locked
4) Wheels chocked
How long after shutdown must you wait to check engine oil level? When must it be at the full line?
20 minutes. Flights over 6 hours.
What hydraulic pump temperatures requires and entry on the 2408-13-1?
> 132 degrees Celsius
How many first aid kits are in the helicopter? Fire extinguishers? Crash axes?
3 First Aid Kits
2 Fire Extinguishers
1 Crash Axe
What are the emergency exits on the helicopter?
Either cockpit door (or windows if Navy style windows are installed), or cabin windows.
Describe the fuel flow through the engine?
Low Pressure Fuel Pump Fuel Filter HMU Liquid to Liquid Cooler ODV Fuel Nozzles
What are the methods of refuel, and what are the maximum fuel pressures and flows associated with each?
Gravity
Pressure - 55 PSI at 300 GPM
Closed Circuit - 15 PSI at 110 GPM
When do the FUEL LOW cautions appear?
Approximately 172 lbs
When must a fuel sample be completed?
1) Before the first flight of the day
2) After adequate settling time after cold refueling
3) If the fuel source is suspected to be contaminated
Where does the APU get fuel from?
The #1 fuel tank
When is the prime/boost pump actuated (3 conditions cause it to activate)?
1) During engine starts when the starter is engaged
2) When the FUEL PUMP switch is moved to the FUEL PRIME position
3) When the APU is started and operating
Can an engine be primed when the other engine is running?
No, the prime pump capacity is not enough to prime an engine when the opposite engine is running.
What is the capacity of the fuel tanks? What type of refueling will allow for the most fuel to be added to the tanks?
360 gallons (180/tank) Gravity refuel will allow the most fuel to be added
How much pressure do the hydraulic systems supply?
3000 PSI
How are the #1 and #2 hydraulic pumps driven? The backup pump?
The #1 and #2 hydraulic pumps are driven by the accessory modules (in response to RPM R). The backup pump is driven by an AC electric motor.
How many filters are located on each pump? When do the impending bypass buttons pop up for each filter?
2 - a pressure and a return filter.
The red buttons will pop when pressure goes up 70 +/- 10 psi above normal.
Why is bypass required for the hydraulic system? Is there a bypass on the return and pressure filters? When will the bypass valve open?
To prevent hydrostatic lock. There is no bypass on the pressure filter. The return filter bypass valve opens at 100 +/- 10 psi above normal.
When do RSVR LOW cautions appear?
60% fluid remaining
What does the #1 hydraulic system supply pressure to?
1) The first stage of all primary servos
2) The first stage of the tail rotor servo
What does the #2 hydraulic system supply pressure to?
1) The second stage primary servos
2) The pilot assist servos
What does the backup hydraulic system supply pressure to?
1) Emergency pressure to the #1 and #2 hydraulic systems
2) The second stage of the tail rotor servo
3) The APU accumulator
The pitch trim servo requires how much pressure? How does the pressure change from one amount to another?
1000 PSI. It is reduced via a pressure reducer.
When does the impending bypass button pop up on the Pilot Assist Module?
1375 PSI
What 2 things can only be pressurized by the backup hydraulic system?
Second stage of the tail rotor servo and the APU accumulator.
What are the time differences for the backup pump to come on when the main generator is operating vs when the APU generator is operating?
0.5 seconds when the main generator is operating and 4 seconds when operating from the APU generator on external power.
The depressurization valve reduces output pressure of the pump upon startup of the electric motor to reduce its current demand and torque requirement.
What 5 lights cause the backup pump to come on?
1) RSVR 1 LOW
2) HYD PUMP 1 FAIL
3) T/R SERVO 1 FAIL
4) HYD PUMP 2 FAIL
5) APU ACCUM LOW
What boost servos are on the helicopter?
Collective, Yaw, and Pitch
What happens if there is a leak in the APU Accumulator?
The flow rate should increase. When it increases to 1.5 GPM (normally the flow is 1 GPM), the velocity fuse un the utility module will shutoff flow to the accumulator, preventing all of the fluid from being drained from the backup pump.
Can both #1 and #2 primary servos be turned off at the same time? Why?
No, they cannot because of an electrical interlock.
Describe a leak in the #1 system
- A leak is detected and the RSVR 1 LOW Caution appears
- LDI isolates the #1 TAIL RTR SERVO, turns on the backup pump, and pressurizes the #2 TAIL RTR SERVO
If the leak continues:
- The HYD PUMP 1 FAIL caution will appear, the transfer valve in the #1 transfer module will move over, the #1 hydraulic pump will be isolated and the backup pump will pressurize the #1 system.
- Hydraulic logic will automatically restore the #1 TAIL RTR SERVO.
If the leak continues:
- The BACKUP RSVR LOW caution will appear and the pilot must isolate the #1 PRIM SERVO.
- If the pilot does not isolate the servo, all of the hydraulic fluid will be lost through the backup pump, and the backup and #1 systems will be inoperative.
Describe a leak in the #2 system
- A leak is detected and the RSVR 2 LOW caution will appear.
- LDI isolates the Pilot Assist Area (BOOST SERVO OFF, SAS OFF, FPS FAIL, and TRIM FAIL cautions will appear).
If the leak continues:
- The HYD PUMP 2 FAIL caution will appear, and the backup hydraulic pump will come on.
- The transfer valve in the #2 transfer module will move over, the #2 hydraulic pump will be isolated, and the backup pump will pressurize the #2 system.
- Hydraulic logic will restore the pilot assist area.
- If the leak stops there, the pilot must do a power on reset to get back FPS and TRIM.
If the leak continues:
- The BACKUP RSVR LOW caution will appear and the pilot must isolate the #2 PRIM SERVO.
- If the pilot does not isolate the servo, all of the hydraulic fluid will be lost through the backup pump and the backup and #2 systems will be inoperative.
What will happen if the #1 pump fails?
- HYD PUMP 1 Fail Caution will appear and T/R SERVO 1 FAIL caution will appear.
- Hydraulic logic will turn on the backup pump.
- Pressure from the backup pump will reposition the transfer valve in the No. 1 transfer module, pressurizing the No. 1 system, and it will operate the second stage tail rotor servo.
- The pilot should move the TAIL SERVO switch to BACKUP and then NORMAL for continued system redundancy in the tail rotor.
What will happen if the #2 pump fails?
- HYD PUMP 2 FAIL Caution will appear.
- TRIM FAIL, FPS FAIL, BOOST SERVO OFF, and SAS OFF cautions will briefly appear.
- Hydraulic Logic will turn on the backup pump.
- Pressure from the backup pump will reposition the transfer valve in the No. 2 transfer module, pressurizing the No. 2 system (including the Pilot Assist Area).
- The BOOST SERVO OFF and SAS OFF cautions will appear.
- The pilot should do a power on reset to get full control of the pilot assist area.
How many bleed ports are on the engine and what do they do?
- One provides air to the anti-ice start bleed valve and the other two provide air to the pneumatic system and engine inlet anti-ice.
What is the purpose of the APU?
It is used to start the main engines, cabin heating, and electrical power for ground and emergency in-flight electrical operations.
What is the air source for starting the APU?
The APU Accumulator
When does the APU ACCUM LOW advisory appear?
2600 PSI
What should you do if the APU fails?
If the APU FAIL light appears, note and analyze the bite indications before cycling the battery, or attempting another start.
If the APU ACCUM LOW light hasn’t come on, you can pull the manual override lever on the accumulator manifold and hold it until the APU has reached self-sustaining speed.
How much is max torque reduced with use of engine anti-ice?
20% TRQ
When do the ENG ANTI-ICE ON advisories appear?
- When the ENG ANTI-ICE is on
- During low power settings until NG reaches 88-92%
- In the event of an electrical failure the start bleed valve will open and the advisories will appear
When must the engine inlet anti-ice come on? When might it come on? When won’t it come on?
Must - 4 degrees Celsius and below
May - Above 4 degrees Celsius to 13 degrees Celsius
Will Not - Above 13 degrees Celsius
When will the ENG INLET ANTI-ICE ON advisories appear?
When the temperature of the inlet fairing gets above 93 degrees Celsius.
What are the requirements for performing a cross-bleed start?
Anti-ice advisory on the source engine must be off, NG above 90%, and RPMR at 100%.
What type of bearings are used in the main rotor system? Tail rotor?
Main - Elastomeric bearings
Tail - None. The tail rotor is a bearingless system.
What type of rotor system is the main rotor? Tail rotor?
Main - Fully Articulated (it can feather, flap, and lead/lag)
Tail - Rigid
What is the cant of the tail rotor? How much total lifting force does it supply in a hover?
20 degrees cant which provides 2.5% of the total lifting force in a hover.
What does a TAIL ROTOR QUADRANT caution indicate?
That a tail rotor cable has been severed.
What happens if both tail rotor cables fail?
The centering spring will position the tail rotor servo linkage to provide 10.5 degrees of pitch.
If both cables fail, is trimmed flight available? At what airspeeds?
Trimmed flight is available between 25 KIAS to 145 KIAS (depending on gross weight).
What type of current is the primary source of power for the helicopter (AC/DC)?
AC
When does the APU GEN ON advisory appear?
When only the APU generator is supplying power to the system. It will not appear when either the No. 1 or No. 2 generator is supplying power.
How is primary DC power obtained?
From 2 converters with the batteries as a secondary power source.
How are the main generators cooled?
With transmission oil.
What busses are powered when only the batter switch is on?
BUB - Battery Utility Bus
Battery Bus
DC Essential Bus
What allows power from one generator to power all of the other generators’ main busses?
Current Limiters
What are the functions of the GCU?
Feeder Fault - when there is a short circuit, the generator is disabled.
Under Frequency Protection - during ground operations only, it is disabled by the WOW switch. It disables gens below 93-95%.
Current Limiting - if there is excessive current demand to the generator, it will be disabled.
Voltage Regulation - regulates to 115/200 VAC.
Over Voltage - if output voltage rises above 125 VAC, the generator will be disabled.
Under Voltage - if the output voltage drops below 100 +/- 5 VAC, the generator is disabled.
How long can the SLAB battery operate in flight if it is the sole source of power?
Approximately 15 minutes (less when using the searchlight).
When do the BATT LOW CHARGE caution appear?
When voltage on the BUB drops below 20.5 VDC.
What does a GEN BRG caution indicate? When does it have to be written up?
A GEN BRG caution indicates a worn or failed bearing. It needs to be written up if the GEN BRG caution appears for more than 1 minute.
Can we continue to fly if a GEN BRG appears? For how long?
Yes, the auxiliary bearing will allow 10 additional hours of operation after the caution appears.
