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350 Cards in this Set

  • Front
  • Back
What does the AC power system provide?
115/200 volt, three–phase, 400 Hz power on six AC buses, for systems requiring alternating current as a
primary power source.
What components enhance the aircraft performance in cold weather environments?
Variable frequency generators (VFG).
In the event of a generator or main contactor failure, what provides automatic backup power from
an operating generator?
Crosstie contactors.
What are the only generators that can supply power to the left and right nacelle ice protection
systems?
Variable frequency generators 3 and 4.
What ensures alignment (indexing) of the CFGs to the gearbox mating plate and oil ports, and
what provides gearbox rotational torque for the CFG?
An anti–rotation pin. The gearbox mating spline.
At what percentage of the proprotor speed (Nr) will the CFG generators come on line? At what
percentage will it drop off line?
The generator comes on line at about 71percent proprotor speed (Nr). The generator will not drop off line
until the input shaft speed is reduced to about 67percent Nr with WOW.
How do the two oil ports from the MWGB and TAGB provide “maintenance free” lubrication for
the CFGs?
The term “maintenance free” means that generator oil servicing is not required on the aircraft.
What functions does the generator integral GCU perform?
Over/under frequency, over/under voltage, bus fault and differential feeder fault protection is provided by a
GCU, and provides the central integrated checkout interface to annunciate generator fail, contactor fail,
channel fail, or bus inhibited (short circuit detected on bus).
What type of generators are VFG numbers 3 and 4?
Generators number 3 and 4 are 80 KVA, oil cooled, VFGs. VFGs provide 115/200 VAC, three–phase, 360
to 457 Hz primary power for the nacelle ice protection system and environmental buses.
Which winding section of the VFGs provide a maximum rated continuous power output of 420
VA at 0.8 power factor (26 to 62 VAC) for the flight control system?
A separate and isolated winding on the permanent magnet generator (PMG) section of the generator.
How are the VFGs driven?
VFG 3 is driven by the main engines only, while VFG 4 is driven by the MWGBs or engines.
How are the VFGs KVA rating determined?
By its oil temperature. At oil temperatures from -54 degrees C to 75 degrees C, the VFG is rated at 80
KVA. With oil temperatures from 76 degrees C to 95 degrees C the VFGs are rated at 50 KVA.
What components provides interface to annunciate failures in the AC system? These failures
could be over/under frequency, over/under voltage, differential feeder fault, generator contactor
failure, bus fault, oil level, or bearing failure indication.
The GCU.
What are the types of contactors that are part of the AC power system?
Bus contactors, emergency contactors, ice protection contactors, environmental bus contactors, wing feed
contactors, and an ice protection crosstie contactor, are the contactors that are part of the AC power system.
. When provides a path to connect external electrical power to the aircraft AC power system (AC
buses)?
External power contactor, when the contactor is energized.
What interchangeable components measure current in the feeder lines by monitoring current flow
through the three–phase primary feeder lines?
Each of the 10 current transformers in the AC power system.
What is the purpose of the four DPST generator reset switches located on the overhead circuit
breaker panel?
The switches provide the operator with manual control to turn the CFGs and VFGs ON or OFF, or to reset a
generator should the system require a reset.
During ground operations, with both main engines shutdown and only the APU running, what
provides all AC power for AC BUS 1/AC BUS 4, AC BUS 2, ENV Bus 1, and ENV BUS 2?
CFG 1.
In what mode of operations are the two nacelle ice protection system buses powered?
During normal flight operations, with main engines running.
How are AC power system manual and automatic control provided?
AC power system manual control is provided by During normal flight operations, with main engines running. four switches on the overhead circuit breaker panel. Automatic control is provided by the GCUs
What components provide current protection for the SIRFC and AERPS?
Circuit breakers.
What type of circuit breaker has one feeder contact and one load contact?
Single–phase circuit breaker.
What components contain contactors, current sensors, and terminal boards to connect, route, and
sense aircraft electrical power?
Power distribution panels.
What components jumper electrical power to a group of system circuit breakers or electrical components?
Bus bars.
How do capacitor power filters eliminate undesired noise and frequencies from the respective bus
power and return leads?
The filters provide feed–through filtering, which eliminates high frequency noise as part of EMI protection.
How many AC bus filters are located in the circuit breaker panels?
A total of 20.
What component continuously checks that the voltages are within tolerance (109–115 VAC) on
each phase of the bus?
Bus health monitors.
What part of the AC power distribution system provides 115 VAC, three–phase, 400 Hz electrical
power for aircraft support and test equipment operation?
Four cabin utility receptacles.
If distribution of power to the cabin utility receptacles is not monitored, how is each receptacle
protected?
Each cabin utility power receptacle is protected by its own dedicated circuit breaker.
On the CDU, how is a failed bus displayed on the STAT ELEC layer?
A failed bus is red.
What components provide AC to DC conversion for those systems requiring DC voltage?
DC regulated converters (CV).
How is DC voltage monitored?
Each CV monitors DC voltage supplied to its bus contactor and adjusts its output accordingly.
How is cooling provided for the CVs ?
CV 1 and CV 2 are cooled by the avionics cooling system. CV 3 is cooled by a dedicated external fan that
uses draw–through air for cooling.
What does the aircraft battery provide primary power to?
The UNSW BAT BUS and via remote control circuit breaker number 2 (RCCB 2) to the MAINT BUS. The
aircraft battery also provides backup power to the ESS/BATT BUS, and may be used to supply power to
the APU electrical starter through the APU–START battery contactor.
What allows the battery to be electrically heated during cold temperatures?
A battery heater thermostatically controlled and powered by 115 VAC is built into the case.
What provides the capability to test the battery voltage level; provides the crew with indications
of battery status while on the ground, and provides a direct reading of the battery voltage?
The battery test panel and indicator, located in the overhead console in the cockpit.
What solid–state device contains the timing, logic circuits, and relay that automatically
disconnects the aircraft battery from the ESS/BAT BUS after five minutes to prevent excess
battery drain during ground servicing?
Battery relay control unit (BRCU).
When de–energized, what component provides a circuit that allows the battery to be connected to
the ESS/BATT BUS?
APU start battery auxiliary relay.
What provides the ground crew with an access to turn off the aircraft battery power without
entering the aircraft?
An external ground support panel.
What connects/disconnects the battery to the ESS/BAT BUS? What connects/disconnects the
battery to the MAINT BUS?
Remote control circuit breaker 1 (RCCB 1). Remote control circuit breaker 2 (RCCB 2).
What is used for visual verification of the status of an RCCB?
A red/green trip indicator.
What component in the DC power system automatically connects an alternate power source to the affected DC bus in the event of a system WRA failure?
A crosstie connector
What functions are provided by the ABIU and WIU for DC bus monitoring?
The ABIU provides the bus health monitor function for DC BUS 2, DC BUS 3, and the essential/battery
BUS. The WIU provides the bus health monitor function for DC BUS 1 (Note: DC BUS 4 is tapped from
the same terminal block as DC BUS 1).
What provides individual protection to aircraft systems against excessive amperage use?
Circuit breakers.
What is utilized on each circuit breaker to manually open or close the contacts applying power to
the aircraft system circuits?
A push/pull actuated plunger.
How is the grid location system utilized with the circuit breaker panels?
Numbered rows and alphabetical columns aid in determining the location of a circuit breaker.
What provides a common connection point for power distribution, and are non–conductive strips
or blocks with spaced metal posts or receptacles used to attach terminal ends or pinned wires to
provide a common power or return (ground) point for aircraft wiring?
Terminal boards.
What is the purpose of feed–through capacitor filters between the DC buses and the DC circuit
breakers?
Filters are provided for both the power leads and the aircraft ground return leads to provide feed–through
filtering to eliminate undesired noise and frequencies as part of electro–magnetic interference protection.
What provides an automatic crosstie connection in the event of CV or main bus contactor failure?
The respective contactor buses.
What types of contact sets are there in the AC power distribution system contactors?
A contactor contains a single–pole single-throw (SPST) normally open main contact set, a three pole
double–throw (TPDT) auxiliary contact set.
What single–phase circuit breakers provide circuit control for the DC power distribution system?
DC bus health monitors.
How are operational and failed buses statuses displayed on the CDU STAT ELEC layer?
Operational buses are green; failed buses are red.
What solid–state electronic device continuously monitors the quality of the external power source for correct phase sequence, voltage, and frequency, and protects the aircraft electrical system from receiving an unstable electrical input?
External power monitor.
What provides a manual control capability to apply or remove external electrical power from the
aircraft electrical system?
External power switch, located on the cockpit overhead circuit breaker panel.
What is the purpose of the six pins on the external power receptacle?
Four large pins (labeled A, B, C and D) are used to connect the three phases of AC power (A, B, and C)
plus provide a return (ground pin D) to the aircraft electrical distribution system. Two smaller pins (labeled
E and F) provide a system interlock function.
In the de–energized position, what provides a path between AC BUS 2 and AC BUS 1 to create
an electrical distribution system crosstie?
External power contactor, located inside PDP 1.
What relay reports the status of an external power condition (CONNECTED or READY) to the
ABIU for the cockpit displays?
External power aux relay.
Are the two nacelle ice protection systems powered with external power applied, and both main
engines and APU shutdown?
No, the two nacelle ice protection systems are not powered.
What are the identification numbers used for reference designators in the wiring system for
system, sub–system, and sub–sub system identification based on?
The unified numbering system (UNS).
What are the functions of reference designators?
They are used to identify WRAs and SRAs on wiring diagrams. The equipment list for each program
identifies the diagram WRAs or SRAs by the applicable reference designators. The reference designator
can be used to locate WRAs or SRAs on a wiring diagram containing that reference designator.
What circuit classification identifies electro–explosives?
Category VII.
What types of cable wiring are not repairable and must be replaced?
Fuel cell internal cables, phase matched coaxial cables, and explosive ordinance detonation cables.
How is the physical protection for an IWS harness provided?
By an outer braided cover.
How is flight control system (FCS) wiring uniquely marked to distinguish from other system's
wiring?
The flight controls wire harnesses have a black overbraid with a different color tracer for each FCC
channel, or blue tape with the flight control system number labeled on the tape.
Why doesn’t the IWS harnesses located inside the left or right avionics racks have a metal
overbraid?
These harnesses have a copper foil shield. Construction of the avionics racks provides sufficient EMI
shielding.
Are repairs to the IWS harness permitted on the flex section?
No. Repairs to the IWS harness are not permitted to the flex section of the harness defined as six inches
from the base of the connector to six inches beyond the first clamp.
What type of cable harnesses are used extensively in the AC and DC power distribution systems?
Conventional wire harnesses.
What does a hybrid wiring harness consist of?
A hybrid wire harness consists of both conventional (individually shielded and/or unshielded) wires and
IWS wires.
What repairs can be performed on RF wire harnesses at the organizational maintenance level?
Only emergency repairs can be performed. Coaxial cable repair should not be performed except to
repair/replace a damaged connector. Those coaxial cables designated as phase matched are not repairable.
What is the maximum length for data bus coupler stub wiring for data bus wire harnesses?
The maximum length for data bus coupler stub wiring is 18 inches.
What provide system integration and isolation for aircraft wire harnesses?
Wiring integration assemblies.
What is the purpose of WIA mounted relays?
WIA’s contain relays that are mounted to provide access for relay removal/installation without removal of
the WIA from the aircraft.
What does the flight compartment lighting system primary and secondary lighting consist of?
The primary lighting consists of internal panel lighting for light plates, illuminated switches and indicators.
The secondary lighting consists of cockpit dome lighting, cockpit utility lights, secondary console lighting,
and alternate power for console panel illuminated push button switches.).
What is the purpose of the lightplate assemblies?
They provide an internal light source for each control box/panel face.
What provides power to the lightplates and backup power to the illuminated pushbuttons?
From the primary lighting control unit (PLCU).Backup power is from the secondary lighting control unit
(SLCU).
What lights are attachable/detachable; use a coiled four foot power cord, and are used as a handheld light source and positioned to illuminate the center console as a fixed light source?
The left and right cockpit utility lights mounted on each side of the overhead console.
What lights provide an alternate or backup lighting source for illuminating the overhead console panels?
The left and right overhead secondary lights.
What lights alert the aircrew of abnormal system conditions?
Warning/caution lights.
After the master alert lights illuminate, when or how will they extinguish?
Once illuminated, the master alert lights will extinguish when either light reset is pressed on the front of the
light assembly, or automatically when the abnormal condition no longer exists. If the lights were
illuminated as a result of the lamp test switch being depressed, the lights will extinguish when the lamp test switch is released.
What relays provide dimming control of the warning/caution switch and indicator lights?
Warning/caution lights dimming relays.
What provides ON/OFF and continuous intensity control of lighting within the flight compartment?
The flight compartment lighting control switches and potentiometers located on the primary lighting control
panel and the master lighting control panel, and the cockpit utility lights control.
What mode of operation switches the affected cockpit lights from white light to green and the maximum brightness levels are reduced?
In the NVIS mode.
What identical and interchangeable lights provide general purpose interior lighting to the passenger compartment cabin area?
Four cabin dual–lamps (white/NVIS compatible) selectable dome lights located in the passenger
compartment.
What do the cabin panel lights include?
Aft cabin crew intercom panel, crew chief crew intercom panel, troop commander crew intercom panel, and
forward cabin control station panel.
What provides lighting for the cabin compass?
The light is built into the cabin compass bezel mount and provides lighting for illumination of the cabin
compass.
Where is the control for the cabin dome‘s OFF through BRIGHT intensity control?
The LIGHTING CABIN DOME potentiometer on the forward cabin control station.
What provides operating power and intensity control for the passenger compartment dome lighting and passenger compartment panel lighting?
The secondary lighting control unit (SLCU).
What provides the capability for visual recognition of aircraft position during night formation flying, SAR operations, night in–flight refueling, cargo handling and landing maneuvers?
The external lighting system.
What provides a 3–axis aircraft attitude reference to other aircraft?
Six blue/green electroluminescent, night vision imaging system (NVIS) compatible formation lights.
Where are the longer and shorter formation light units installed?
Longer units (12 inches) are installed on the outboard side of each vertical stabilizer. Shorter units (9
inches) are installed on the inboard top of each Nacelle and on top of each aft wing fairing.
What shows the positions of the aircraft proprotors to other aircraft during formation flights?
Two interchangeable light–emitting diode (LED) light assemblies are installed on the tip of each proprotor
blade, with one visible from the top and the other from the bottom.
Where are the position lights installed to assist in determining the aircraft's direction/position at night or during low visibility conditions?
The nacelle fuselage position lights are located on the outboard side of the engine nacelles, red (left) and
green (right). A white tail (navigation) position light is located on the left vertical stabilizer trailing edge.
How do the anti–collision lights function during NVG mode?
The top anti–collision light can be switched to infrared while the bottom anti–collision light is disabled.
The type of lamps does the hoist operator's light have to provide lighting for hoisting or external cargo operations?
One clear for visible lighting, and one infrared for NVG operation.
How is the in–flight refueling light housing designed to aid maintainers in properly replacing the fixture?
The light housing is labeled with an UP orientation arrow to ensure the light is directed in the correct
direction.
What are the capabilities of the two retractable search/landing lights?
They are capable of search throughout the lower hemisphere, providing illumination of the landing/takeoff
area for night operations and are used as searchlights and are also capable of 360 degree rotation and +20 to -90 degree elevation.
What identifies the left–hand search/landing light assembly when connected to the aircraft's electrical connectors?
The left search/landing light assembly aircraft electrical connector contains a jumper that identifies it as the
left–hand light when connected to the aircraft's electrical connectors.
What provides ground crew with an indication that the landing gear is down and locked?
The landing gear down light.
How is the ON/OFF control function of the hoist operator's light controlled?
By a push button switch on the cargo hook hoist/winch operators grip.
What are the five designated emergency exits does the emergency egress lighting system (EELS)
provides emergency lighting for?
Main cabin door, forward left escape hatch, forward right escape hatch, aft left escape hatch, and aft
overhead escape hatch.
How do the five EELS light assemblies provide lighting?
When illuminated, the light assemblies provide yellow–green lighting arranged in an inverted U pattern
around each emergency exit. Each of the five electroluminescent light assemblies is identical and consists
of three sections.
How are the emergency exit escape hatch light assemblies secured to the fuselage?
Captive fasteners and tiedown straps.
What component provides system interface and control for charging power and system logic control for the EELS light assemblies?
The signal conditioning box is located on the right side cabin area, just forward of the right aft window,
center cabin overhead.
For how long are the self–contained, rechargeable 24 VDC battery pack in the EELS control boxes capable of providing illumination power?
When fully charged, the battery packs are capable of providing sufficient power to illuminate several
emergency egress lighting assemblies for a minimum of ten minutes.
When the 28 VDC is removed (power removed from the aircraft), what maintains the EELS
control box in an extended operational state for one hour?
A solid state countdown timer.
What is provided on the EELS control boxes for maintenance testing?
A press–to–test button and two LEDs on each EELS control box.
When the EMERG EGRESS switch is put in the ARM position, under what conditions will the emergency exit lights and cabin door lights come on?
If the aircraft electrical power buses are powered or have been powered within the previous one hour and
the signal conditioner box senses that rotor RPM is below 20 percent.
What transfers control of the emergency exit lights and cabin door lights to the cockpit?
The CKPT CNTL switch position on the cabin emergency egress lighting control panel transfers control to
the EMERG EGRESS ARM/OFF switch in the cockpit.
What comes on to indicate the presence of battery charging power (28 VDC) and the satisfactory health of the internal battery charging circuit?
The POWER LED on the EELS control box during press-to-test.
What systems do the lighting control system provides operating power and intensity controls for?
Flight compartment lighting system, passenger compartment lighting system, and external lighting system.
What provides the pilot/copilot with an annunciation of warning and caution conditions that have occurred?
The left/right NVIS red master alert lights.
What switch will illuminate all switch and indicator lights to check circuit continuity and lamp integrity?
The LAMP TEST switch on the master lighting control panel.
What switch provides a signal to the PLCU for either day (brighter) or night (dimmer) panel switch/indicator lighting intensity settings and for panel light plate illumination in night mode?
The DAY/NIGHT switch on the master lighting control panel.
How do the PLT, CPLT, and OVHD lighting control potentiometers on the master lighting control panel vary the lighting for each zone?
Moving the lighting control potentiometer out of the OFF position and rotating it clockwise increases the
intensity of the lighting in the respective zones for PLT, CPLT, and OVHD.
What provides DAY/NIGHT mode select lighting control for controlling the intensity of the flight compartment panel switches and indicator light?
The primary lighting control unit (PLCU).
What provides control power for energizing the power source select relays for switching flight compartment panel switches and advisory indicator lights power from the PLCU to the SLCU when the PLCU power fails (auto–activation)?
The secondary lighting control unit (SLCU).
What subsystem of the compression system provides for the intake, particle filtration, and high velocity movement of compressed air?
The compression system.
What component provides a source of compressed air to the ECU under normal conditions and is
attached to the MWGB assembly?
The shaft driven compressor (SDC).
What compression system components provide control of compressed air outlet pressure,
unloading the SDC during APU startup, or sensed low oil pressure conditions?
The inlet guide vane and the hydraflow surge control valve.
In the compression system, when the ECS is selected ON, what does the solenoid valve located
on the top of the SDC do?
The solenoid valve opens the SDC inlet guide vanes and closes the SDC hydraflow surge control valve. The
solenoid valve provides flow and shutoff of oil to the inlet guide vanes/hydraflow surge control valve for
control of the system.
What compression system component functions to provide a discrete input to the CMS for
indication of metal particles detected within the SDC lubrication system?
The drain plug/chip detector located on the lower forward side of the SDC.
What compression system component provides discrete input to the FMU for add oil indication of
the SDC lubrication system requiring service on the GRDP?
The oil level switch is located on the aft side of the SDC.
What monitors the ECU temperature/leak sensor for indication of breaks in the ducting or failed
hydraflow couplers, and monitors the ECU inlet pressure transducer for indication of improper
SDC operation?
The environmental control system (ECS) controller.
What action will result when the CDU ECS select key is ON?
The SDC solenoid valve is energized open. This solenoid action will result in the surge control valve
closing and the inlet guide vanes opening allowing the compressed air from the SDC to the ECU inlet.
What prevents foreign object debris (FOD) from entering the SDC air inlet? What provides for
the removal of FOD from the SDC inlet air?
The outboard opening of the inlet is secured to an aluminum mesh fairing. The SDC inlet particle separator
(IPS).
How are the compressed air ducts constructed?
The ducts use a double wall construction; the inner wall is a titanium pressure carrier, and the outer wall is
an insulation shroud made from a phenolic/fiberglass laminate with an inner layer of aluminum foil bonded
to it.
What provides a connection between the compressed air ducting in the cabin to the ECU, and
provides a connection between the pneumatic ground power cart air connection and the ECU?
The ECU intake duct is located in the ECU bay.
What provides a connection point for a pneumatic ground power cart to power the ECU when the
SDC is not running?
The pneumatic ground power cart air connection assembly, located forward of the ECU bay at the aft left
sponson.
In the air distribution system, what will shut the emergency vent fan off in case of fan motor
overheat, and will provide unfiltered ambient air to the cockpit and cabin in the event of ECU
failure?
A thermal protection circuit.
What is the function of the avionics cooling system?
The avionics cooling system provides for independent cooling of the equipment in the left, right and nose
avionics compartments, and maintains the temperature of the avionics bays within limits.
What fan provides cooling airflow for the components inside the multi–mode radar (MMR) pod
and the nose compartment?
The nose bay cooling fan, located under the cockpit floor on the left side of the aircraft behind access panel
1LS1.
What types of filter assembly filters any foreign particles that pass through the IPS?
The assembly contains two paper fabric internal throw away filter elements, which are approximately
thirty–six inches long and twelve inches in diameter and the elements are secured to the filter housing by a
V–band clamp. The left filter cleans air from the left IPS, and the right filter cleans air from the right IPS.
What filters eliminate electromagnetic interference from being transmitted through the avionics
cooling system?
Eight electromagnetic interference (EMI) filters located in the left and right avionics racks.
What component senses high temperatures in the nose bay and provides a NOSE BAY HOT
signal and/or a LEFT or RIGHT BAY HOT signal to the ABIU?
Temperature sensors installed in the nose bay and left and right avionics compartments.
What fan provides cooling airflow for the cabin overhead SIRFC receiver processor?
The LRU 1 cooling fan is in the duct located in the cabin overhead to the right of centerline.
What does the empennage cooling consist of?
Empennage cooling consists of the cooling components for the SIRFC counter measures transmitter and
modulator receiver (aft LRU 2/3).
What does the environmental control unit (ECU) provide?
Provides conditioned air (heating or cooling) to the aircraft air–conditioning system; provides partially
conditioned air to the on board oxygen generating system/on board inert gas generating system
(OBOGS/OBIGGS), avionics cooling, and the wing pneumatic deice system.
What type of barrier filters are located in a plenum between the ram/fan inlet air particle separator
and the primary secondary heat exchanger?
The barrier filters are constructed of pleated 100 percent cotton cloth sandwiched between stainless steel
wire mesh. The rectangular shaped filter frame is constructed from black polyurethane with permanently
and legibly marked arrows to signify the direction of airflow. The filters are cleanable, and require oiling
prior to reinstallation.
What cools SDC air through a process of heat transfer using aircraft ram air and ACM fan air?
The primary/secondary heat exchanger.
What three simultaneous duties does the ACM perform?
The fan impeller will increase ram airflow for increased cooling; the compressor section will increase air
pressure for ECU operations, and the turbine section provides the energy to drive each stage of the ACM
while cooling turbine discharge air.
What component significantly lowers the temperature of the air to improve the performance of
the water extractor at removing moisture, and helps raise the temperature of the turbine outlet air
above freezing requiring less additional heated air to prevent ice from forming?
The condenser portion of the re–heater/condenser heat exchanger.
What removes condensed moisture from the compressed air flowing out of the condenser section
of the re–heater/condenser heat exchanger?
The water extractor.
What controls or shuts off the flow of compressed air flowing through and around the re–heater
section of the re–heater/condenser?
The re–heater diverter valve, located at the cold side inlet of the re–heater heat exchanger.
What controls the relative proportion of total airflow going to the cockpit and cabin?
The proportioning valve, located in the cabin supply duct on the left side of the aircraft below the NO. 1
CIRCUIT BREAKER PANEL.
What type of fans are the emergency vent and the recirculation fans?
Electrically driven, vane–axial fans.
How are O2 tubes labeled?
O2 tubes are labeled with tape that identifies oxygen tubes with a green band followed by a band of
rectangle symbols and the legend BREATHING OXYGEN. The flow direction is indicated with an arrow
on the tape.
What is used to connect different diameter tubes together in the oxygen distribution system?
Reducing tees.
How many crew members can the on–board oxygen generating system (OBOGS) support and
under what conditions?
Sufficient oxygen for four crew members under all temperature and altitude conditions.
How does the oxygen/nitrogen (O2/N2) generating system produce oxygen enriched and oxygen
depleted gas?
The system uses pressure swing adsorption to produce oxygen enriched and oxygen depleted gas. The
process uses two different types of synthetic zeolites (molecular sieves) to separate oxygen and nitrogen
molecules.
What in the maximum percentage of oxygen in the oxygen–depleted air that is continuously
supplied to the fuel tanks?
Not more than 7 percent oxygen.
What component produces oxygen enriched air for crew breathing and nitrogen enriched (oxygen
depleted) air for fuel cell inerting?
The O2/N2 concentrator.
What component of the 02/N2 generation system connects/disconnects the conditioned and
pressurized (20–40 psig) system input air source from the ECU?
The oxygen plenum shutoff valve, located on top of the concentrator between the oxygen beds.
What provides a supply of oxygen for an emergency descent in the event of an OBOGS failure?
The emergency oxygen system.
What emergency oxygen bottle component will prevent it’s over servicing and will vent over
board at 2500 and 2755 psi?
The high pressure relief valve, located directly behind the pressure valve.
What provides for manual operation of the emergency oxygen solenoid operated control valve in
the event that electrical control is not available?
A manual lever is located on the emergency oxygen solenoid operated control valve.
When the emergency oxygen system is fully charged, how much oxygen will be provided?
Approximately 400 liters of oxygen (approximately five minutes of oxygen for four people).
Where is the emergency oxygen control panel located?
Located on the cockpit overhead control panel.
How are N2 tubes labeled?
Tubes are labeled with tape that identifies nitrogen tubes with a blue and orange band of continuous X–
formed lattice and the legend PNEUMATIC. The flow direction is indicated with an arrow on the tape.
What connects the nitrogen supply to the fuel tanks?
For the fuel and feed cells, an orifice assembly connects the nitrogen supply to the fuel tank.
What are the functions of the check valves in each cell and feed tank?
Permits nitrogen to flow into the cells and prevent fuel from flowing into the nitrogen distribution system
and maintains the nitrogen overpressure in the tanks while parked and for start–up.
What does active fire detection incorporate in the fire detection system?
Heat–detecting pneumatic fire detector assemblies in the engine bays and optical fire detection units located
in the wing tip rib, wing aft cove, wing dry bay and the midwing areas.
What type of detector is required due to the need for faster response times to extinguish ballistic
fires and fires started by other means in the wing tip rib, wing aft cove, wing dry bay, and the
midwing areas?
Optical detectors.
What is the type and purpose of detector assemblies situated within each engine nacelle?
Two redundant, continuous heat sensing, pneumatically operated nacelle pneumatic detector assemblies are
situated within each engine nacelle. The purpose of each detector assembly is to monitor the area for temperature increases and provide output signals that will enable aural and visual cockpit fire warning
indications.
How do the optical infrared detectors detect a fire and what is their field of view?
The detectors will sense two different bands of infrared radiation, light and heat. Each detector has a 120
degree cone field of view.
What types of fires can optical detectors detect?
The optical infrared detectors can detect a large hydrocarbon fuel fire, ignited by a high explosive
incendiary or armor piercing incendiary round, within ten milliseconds of the time the round creates the
fire. The detector will detect a ten inch hydrocarbon pan fire located at a maximum distance of three feet
from each detector within 35 milliseconds after the fire has fully developed.
How does the fire detection system alert the pilots of a fire?
The fire detection system will alert the pilots of a fire via the fire suppression panel, located on the forward
overhead console. The applicable FIRE light will illuminate when a fire is detected.
How is the fire detection system deactivated so that maintenance tasks can be performed on the
affected areas?
By the wing fire disable switch on PDP 3. The switch is a guarded, two position toggle switch.
With the Osprey fire extinguishing system, what areas of the aircraft include fire suppression?
Fire suppression is within the left and right engine nacelles, the left and right wings, and the midwing area.
There is a separate engine fire extinguishing system for each of the two engine nacelles.
What type of extinguishing agent is in each engine fire suppression bottle?
Each engine fire suppression bottle is a 224 cubic inch fire bottle charged with six pounds of HFC–125
extinguishing agent pressurized to 600 psi by a nitrogen precharge.
How is the fire extinguishing agent routed to each nacelle?
During discharge, extinguishing agent is routed up the forward inboard side of each nacelle to three tubes
that release the agent into the nacelle to suppress the fire. At the discharge point the tube is flared to allow
for adequate dispersion.
Under normal and fire conditions, how does the fire door assembly and the two fire
door/actuators in the engine nacelles operate?
During normal operation, the doors will remain open for cooling of the nacelles. When a fire is detected in
a nacelle, the doors/actuators are signaled to close, shutting off airflow to the nacelle. This will contain the fire extinguishing agent inside the engine nacelle when discharged.
What type of agent does the gas generator suppressors contain?
The gas generator suppressors, located throughout the wing and midwing structures, contain an inert, nontoxic, non–corrosive, and non–ozone depleting solid agent material sealed airtight within the gas generator case.
What areas does the wing fire protection controller (WFPC) monitor? What happens if a fire is detected?
Tubes monitor the fire detector/suppressor assemblies in the wing tip rib, wing dry bay, midwing and aft
cove areas. If there is a fire in any of the monitored areas, the WFPC will initiate programmed fire
suppression sequences to extinguish the fire.
What is the result of moving the T–handle to the ARM position on the fire suppression panel?
Moving the T–handle to the ARM position arms the appropriate engine extinguishing fire bottle, shuts off
fuel to the affected engine, removes backup full authority digital electronic control (FADEC) power,
removes hydraulic pressure to the EAPS blowers, and closes the fire doors.
Under what conditions is the fire extinguishing system armed?
The fire extinguishing system is armed whenever power is on the aircraft.
What is unique to the explosion suppression system?
Unique to the explosion suppression system are the powder panel assemblies that contain an aluminum
oxide suppressant used to extinguish a fire resulting from an incendiary round through the forward spar.
Two fire screens are installed in the forward spar in each wing to prevent propagation of fire between the
tip rib bay and the wing leading edge area, forward of the forward spar.
In the explosion suppression system, how many gas generator suppressors are in the midwing?
The midwing has seven gas generator suppressors.
How is fire suppression in the left wing, right wing, or midwing area activated?
Fire suppression in the left wing, right wing, or midwing area is automatically activated upon detection by
the associated optical sensors.
What is provided by the ice and rain protection system and the rain removal subsystem?
The ice and rain protection system provides a means for detecting, preventing, and removing ice and ice
conditions from the aircraft. The rain removal subsystem provides a means for the operators to remove rain,
snow, salt spray, and other foreign matter from the outside of the windshields, and to wash the windshields
with a mechanical wiper/wash system.
What areas are controlled by the ice and rain protection system?
Areas controlled by the ice and rain protection system include the wing leading edge surfaces, proprotor
blades, blade root fairings, spinner assemblies, and the cockpit windshields.
What subsystems make up the ice protection system?
Airfoil ice protection system, proprotor ice protection system, windshield ice and rain protection system,
and the ice protection system control system.
How is airfoil deicing of the wing leading edge accomplished?
Deicing the wing ice protection system leading edge is accomplished by the wing deice boots.
How do the pneumatic deice boots function?
Air pressure for inflating the deice boots is supplied by the MWGB–mounted SDC. Vacuum deflates the
deice boots, which helps retain the boots against the wing leading edge and maintains the aerodynamic
characteristics necessary for air flow across the wing.
What is the inflation duration and air evacuation of the wing deice boots?
The inflation duration of the wing deice boots is five seconds. After five seconds, there is a 15 second air
evacuation period in which a vacuum deflates the boots to return it to its original more aerodynamic shape.
What is the purpose of the wing deice solenoid valves?
The wing deice solenoid valves control the air flow to and from each wing deice boot to provide a regulated outlet flow of 15 – 22 PSIG. They are located in the inboard wing leading edges.
In what modes does the wing ice protection system operate?
The wing ice protection system operates in AUTOMATIC, LIGHT, MODERATE, and OFF modes.
What does the proprotor deicing and anti–icing system encompass?
The proprotor deicing and anti–icing system encompass (integral/built-in heaters) components that remove
or prevent ice buildup on the proprotor blades, blade root fairings, and spinner assemblies.
In the event of a NO. 3/4 VFG failure, how is ice protection for the nacelles affected?
In the event of a NO. 3/4 VFG failure, the ice protection for the affected nacelle will shed all deice/anti–ice
(including blade deice) except for spinner afterbody deice and engine inlet anti–ice. The VFG cannot carry
the entire load of all ice protection systems.
What is incorporated into each proprotor blade to facilitate thermal control?
Anti–ice blanket heater elements and temperature sensor, built into the proprotor blade and located between
the titanium abrasion strip assembly and the proprotor blade spar assembly.
What does the master ice protection control unit (MIPCU) provide?
Provides monitoring OAT sensor and ice detection system, control and monitoring of the left nacelle ice
protection control unit, control of wing deice boot solenoid valves and monitoring the associated pressure
switches, and provides control and monitoring of anti–icing/deicing of windshields, pitot probes, AOA
sensors, and provides protection against electromagnetic environment effects and indirect lightning threats.
What does the nacelle ice protection control unit (NIPCU) provide?
The NIPCU provides control of the nacelle ice protection functions.
What is the function of the blade deice distributors (BDD)?
The BDD’s are a microprocessor based, full authority, digital subsystem. Each BDD switches power
serially to the ten (10) heater zones, and provide pass–through wiring for parting strip power, parting strip
temperature sensors, rotor tip lights, blade fold power, blade fold proximity sensors and slip ring shear pins.
How is deicing accomplished when PRTR DEICE AUTO is selected on the CDU ICE
PROTECTION layer?
The proprotor blades, blade fairings, and spinner assemblies will be deiced/anti–iced automatically
when a preset ice thickness is reached.
What component activates the deice cycle when the ice thickness on any surface reaches the
preprogrammed limit?
The master ice protection controller (MIPC).
What is the result of a failure of the MIPC?
Failure of the MIPC will result in the loss of all anti-ice/deice systems except for engine bleed air anti-ice
which is fail safe to the valve open position.
How are the left and right NIPCU’s powered?
The left and right NIPCUs are powered by the NO. 3 and NO. 4 generators, respectively. The NIPCUs are
not available with only external power.
What component receives icing data signals from ice detector sensors, relays icing data signals to the MIPC and receives controlling instructions from the MIPC?
Ice detector control unit (IDCU).
How do the ice detector sensors function when the ice buildup reaches 0.06 inch?
The sensor is heated for five seconds to remove the accumulation and the sequence is repeated. The icing signal will continue for 15 minutes after the last icing indication. The icing signal is present as long as the
icing persists.
In AIRPLANE MODE, how do the ice detectors sense the presence of icing conditions? How do
the ice detectors sense the presence of ice conditions while in vertical take–off and landing mode (VTOL) and hover mode operations?
In AIRPLANE MODE, ice detectors sense the presence of icing conditions and the anti-icing and deicing is accomplished automatically with no pilot action required. In VTOL and hover mode, proprotor deice and
anti–ice must be manually activated in the presence of visible moisture and an OAT below 45 degrees F.
What is the recommended mixture of washing fluid for the reservoir and motor/pump assembly for ambient temperatures below -4 degrees F?
20 percent water and 80 percent alcohol when temperatures are below -4 degrees F.
What does the motor/pump portion of the assembly provide?
The motor/pump portion of the assembly provides a flow of 14 gph at 18 psi pressure through tubing to the
spray bars.
In strokes per minute, what are the low and high speeds for the rain removal system motors?
The motors have two speeds and produce 120 strokes per minute for the low speed and 180 strokes per
minute for the high speed.
What is the purpose of the left and right lift cams and lift blocks?
The lift cam raises the wiper arm and blade off the windshield while the lift block positions the windshield
wipers in the park position.
If the wipers are off when WASHER is selected, what prevents wiper operation on a dry
windshield?
A 0.8 second time delay occurs between the WASHER and WIPER ON commands, preventing wiper
operation on a dry windshield. After the washer cycle is completed, the wipers will continue to operate for
0.8 seconds, and then will automatically set to off.
The wipers can no longer operate above what airspeed?
Above 140 knots.
What proprotor configuration gives the CV–22 lift and directional control?
HELICOPTER MODE gives the Osprey lift and directional control. AIRPLANE MODE supplies the
Osprey with the thrust required in forward flight as an airplane.
When composite materials must be worked on, what are some of the common safety precautions
associated with composite materials maintenance?
Drilling, grinding, or cutting composite materials require all maintenance personnel to wear respirators
throughout repair and cleanup. Additionally, composite materials contain a copper mesh for distribution
and dissipation of electrical charges.
What is the approximate weight of the hub and blade assembly?
The hub and blade assembly weighs approximately 2000 pounds.
Which component connects the pendulum damper weights to the yoke?
The spindle assembly.
Which component on the proprotor system allows the rotor system to slide on an axis upon it?
The drive tube assembly.
What is the primary purpose of the spinner assembly?
The primary purpose of the spinner is to reduce proprotor drag, provide a conductive path in the event of a
lightning strike and ice removal.
What loads are supported by the proprotor blades?
The blade structure also supports the centrifugal, torsional and bending loads experienced during fight.
What is required when removing a major component, such as a pendulum damper, from the
nacelle?
The wing support adapter assembly should be installed to provide support for the opposite wing. The
adapter assembly is used in conjunction with a 20–ton tripod jack.
What do the blade tip lights provide?
Visual indication of aircraft attitude at night.
What is the lateral envelope of the aircraft in VTOL configuration?
84 feet, 7 inches.
What are the selectable manual positions of the RPU?
INDEXED, LOCKED, and FLY.
What component receives information from sensors and relays the information to the AMC?
The VSLED airborne unit.
What is used to track the alignment of the blades for proprotor smoothing operations?
Optical trackers.
What is the range of adjustment allowed on the pitch links?
0 to 100.
What is the maximum allowable weight for a proprotor blade tip weight?
1.5 pounds.
What type of vibration results from a span imbalance, chord imbalance, and/or aerodynamic
variations between the proprotor blades and their respective installations?
1 / rev vibrations.
Which components allow for adjustments in order to correct proprotor vibrations at the most
optimum level?
Pitch links, tip weights, and chord weights.
Pitch links, tip weights, and chord weights.
15–20 hours.
What is the amount of VSLED data stored in the AMC?
Out–of–balance condition. They occur due to changes in blade pitch.
What is chord imbalance also referred to?
Out–of–balance condition. They occur due to changes in blade pitch.
What is the overall process of rotor smoothing?
The process of measuring track and the 1 / rev vibrations in flight.
What component transmits power from the PRGB to the TAGB?
Pylon driveshaft
What is the nacelle blower driveshaft made of?
Aluminum.
What is the total number of wing mounted driveshafts on the CV–22?
Six, driveshafts L2, L3, L4, R2, R3, R4.
Which the only drive shaft is installed into the TAGB?
Spindle driveshaft.
What driveshaft component provides dynamic system damping?
The single coupling support assemblies
What system is designed to function as a synchronization and power transfer mechanism between
the proprotor systems and accessory equipment?
Interconnecting shafting system (ISS)
What components allow for a more solid connection between a driveshaft and its couplings?
Curvic adapters
What are the three different flexible coupling supports?
PRGB, MWGB, and TAGB couplings
What is capacity of the PRGB oil reservoir?
The reservoir for the PRGB is 7.0 gallons.
At what level of maintenance can oil jets be replaced?
Oil jets are a depot level replacement only item.
What size oil filters does the PRGB incorporate??
The filters incorporated are a 3 micron and a 40 micron.
How many debris sensors does the PRGB incorporate?
The PRGB has 3 debris sensors.
What is the function of the proprotor mast?
The proprotor mast distributes and carries loads to and from the proprotor.
What is the debris monitoring system monitored by?
DSIU.
Which TAGB has an additional idler gear?
The right TAGB has an additional idler gear.
How many sections does the TAGB have?
The TAGB has two sections. One section being the bevel gear section the other being the accessory drive
section.
How many debris sensors are located on the left TAGB?
Two debris sensors per gearbox.
Which components are driven by the left TAGB accessory drive section?
The left accessory drive section assembly drives the following components: oil pump, nacelle blower, no. 1 hydraulic pump, and No. 3 VFG.
How does the TAGB connect the PRGB to the MWGB?
Interconnecting shafting system.
Where is the bevel gearbox assembly located?
Forward portion of the TAGB assembly mounted to the transmission adapter.
What micron filter setup is incorporated in the dual stage oil filter assembly?
3 and 40 micron.
Where is the air/oil separator located?
The air/oil separator is a shaft driven accessory located inboard, aft, and below the oil pump.
What type of debris sensor detects metal in the TAGB lubrication system?
Magnetic capacitor.
What components are mounted to the MWGB?
The rotor brake, RPU, No. 1 CFG, No. 4 VFG, APU, SDC, No. 3 hydraulic pump, and oil cooler/blower
assembly are mounted to the MWGB.
What drives the MWGB?
The APU drives the MWGB. The engines also provide power to run the MWGB through the ISS.
What three visual indications will you get from the MWGB oil sight gauge regarding fluid level?
Under serviced, indicated by a clear sight gauge. Fully serviced will be indicated by the center of the sight
gauge being dark. An overserviced MWGB will be indicated by the sight gauge being completely dark.
What components allow the operation of the MWGB by either the APU or the main engines?
Clutches in the MWGB.
How many cores does the oil cooler/blower assembly have?
Four.
What caution will display on the CDU/EICAS if debris is detected in the MWGB?
A Caution will illuminate on the CDU/EICAS displaying a “CHIPS” indication.
Which component equalizes the internal and external case pressure of the MWGB?
The oil breather.
When driven by the MWGB, what is the gpm flow of the number 3 hydraulic pump in
AIRPLANE MODE and when in HELICOPTER MODE?
32gpm in AIRPLANE MODE; 38gpm in HELICOPTER MODE.
What is the normal operating range of the oil cooler/blower assembly?
20 to 110 degrees C.
What is the purpose of the emergency lubrication system?
To supply oil to a failed PRGB.
How many minutes (maximum) can oil be supplied to a failed PRGB?
30 minutes maximum under a restricted flight scenario.
What component transfers lubricating oil to the left or right PRGB?
Oil pump assembly
What does the ELS dump valve responsible for?
The dump valve provides drainage during ELS operation. The valve prevents the PRGB from being
overfilled.
What component signals the ELS to activate?
The DSIU activates the ELS
What prevents oil from sloshing in the ELS reservoir during flight?
Slosh control baffles in the reservoir.
Where does the emergency lubrication oil go once it is used in the PRGB?
Lubricant is not recycled, but passed overboard through the dump valve.
What feature of some of the ELS hoses helps maintain the integrity of the 30 minute oil flow?
Some of the tubes and hoses are heated as cold oil moves very slowly.
What are the basic characteristics of the AE1107C Liberty engine?
The engines are an axial flow turboshaft, internal combustion engines that produce 6,150 shaft horsepower each.
What four major assemblies make up the engine?
The four major assemblies of the engine are the torquemeter assembly, gas generator assembly, power
turbine assembly and the accessory drive gearbox.
What are the primary and secondary purposes of the torque meter assembly?
The purpose of the torquemeter assembly is to simultaneously measure and transmit the output torque of the
power turbine to the PRGB. Secondarily, it has the capability to measures power turbine shaft (rotational)
speed (Np) in the event of primary Np sensor failure.
How many stages of compression are provided by compressor?
The axial flow compressor has 14 stages.
How are the five variable guide vanes controlled?
The 5 variable guide vanes are controlled by the CVG actuator through the CVG torque tubes.
What kind of design is the combustion liner and what does that mean?
The combustion liner is of an annular design; meaning the fuel air mixture is burned in a circular pattern.
What is the purpose of the gas generator turbine?
The gas generator turbine coverts gas flow into shaft horsepower to rotate the engine compressor and the engine driven accessories.
What is the purpose of the power turbine?
The power turbine extracts gaseous energy from the high temperature gas stream and produces usable
mechanical energy in the form of shaft horsepower to drive the proprotor.
What does the AGB drive do and provide mounting for?
The accessory drive gearbox drives the permanent magnet alternator (PMA), fuel pump and metering unit
(FPMU), lube and scavenge pump, and provides a mounting pad and gear train for the engine starter.
Where are “E” seals used?
“E” seals are located in the turbine assembly and provide a flexible seal on the turbine assemblies where
mating parts are exposed to high pressure air or gas flow.
What is the EAPS responsible for?
The EAPS System is responsible for separating foreign particles from engine inlet airflow in order to
provide clean air for engine combustion.
What are the five major components of the EAPS assembly?
The five major components of the EAPS assembly are the housing assembly, bleed air tubing, blowers,
exhaust ducts, and the housing seal assembly.
What do the fixed turning vanes in the housing assembly do?
The fixed turning vanes deflect the incoming air and debris downward through the scroll section toward the
blowers and exhaust ducts.
Where does the EAPS tubing connect to the EAPS housing?
At the 12 O’clock position
What is the power source and operating speed of the EAPS blowers?
The EAPS blowers operate at 10,500 rpm and are ran by the No. 3 hydraulic system.
What prevents improper installation of the EAPS blowers?
What prevents improper installation of the EAPS blowers?
What is the purpose of the flared surface of the housing seals?
This flared surface will ensure a tight fit between the exhaust duct and the housing seal assembly. In case of
fire this sealed interface helps prevent entrainment of retardant and ingestion of fresh air through the EAPS.
What is the default mode for the EAPS?
“EAPS AUTO” is the default mode that is controlled by the AMC.
What are the compatible fuels for the fuel supply system?
The fuel supply system is compatible with JP4, JP5, JP8, Jet A, Jet A–1, and Jet B jet fuels.
What is the purpose of the CVG actuator?
The CVG actuator controls the movement of the compressor’s variable guide vanes.
What are the two functions of the feedback turnbuckle?
The feedback turnbuckle has a range of 23 degrees providing precise position input, it is also used to lock
the torque tube in position during a fail fixed operation.
How many fuel nozzles are on each engine?
There are 16 identical fuel nozzles.
What does the internal fuel flow divider do?
The internal fuel flow divider ports primary fuel flow to the metering set during engine start and idle; it also
adds secondary fuel to the metering set as the power demand increases fuel pressure compressing the spring
on the secondary port.
What is the primary function of the FPMU?
The primary function of the FPMU is to generate and control the fuel pressure and delivery rate to the
engine fuel nozzles and CVG actuator.
What limits the HP pumps pressure?
The fuel pump pressure relief (approximately 750 PSI) is above the maximum gear pump pressure rise seen
in normal operation limited by the parallel relief valve.
What is the PDSVs function?
The PDSV opens to allow the fluid to return to the HP pump; maintaining a constant 70 psi pressure drop
across the MMV while. The PDSV also acts as a spill valve routing excess fluid back to the HP pump.
What kind of filter is housed in the fuel pump assembly?
This filter is a disposable, 25–micron filter housed in the fuel pump assembly.
What is the fuel cooled oil cooler designed to do?
The fuel cooled oil cooler is designed to cool the oil to below 240° F.
The engine ignition system is comprised of what four components?
The four major components of the ignition system are the PMA, ignition exciter, ignition leads, and the spark igniters.
How many sets/types of windings does the PMA have and what are they dedicated to?
The PMA has 2 sets of three phase windings (one for each FADEC) and 2 sets of single phase windings
(one for each ignition exciter).
Where are the ignition exciters mounted?
Ignition exciters mounted on the top of the engine air inlet housing at the 1 O’clock and 11 O’clock
positions.
What is the output of each exciter during a normal start?
Each exciter provides a minimum of four sparks per second at 3.0 Joules (60,000 Watts) during a normal
start.
Besides providing spark for ignition what else do the ignition exciters do?
They also provide spark and ignition data to the engine monitoring system by an internal spark detector.
What do you need to ensure prior to performing maintenance on the engine ignition system?
Warning: Be careful when you work on the PMA, ignition exciter, tension leads or igniters. Do not touch
any of these components for at least 5 min. after the applicable circuit breakers are open. Always use
insulated tools to remove these components as their electrical discharge can cause shocks, burns, or death.
How many spark igniters are there and where are they located?
There are two spark igniters mounted at the 6 and 12 O’clock positions on the diffuser case.
The engine anti–icing system air is delivered to what components to prevent ice formation?
The anti–icing air system controls the distribution of anti-ice air to prevent the formation of ice on the
engine inlet housing struts, inlet guide vanes, and the EAPS turning vanes.
What percentage of total engine airflow does the 14th stage bleed air account for?
This air is 14th stage compressor discharge air accounts for 4.8 percent of total engine airflow.
What is the temperature and pressure of 14th stage bleed air?
14th stage bleed air is 815°F at 225 psi.
How is the number 4 inlet strut anti–iced?
The No. 4 strut is anti–iced by scavenge oil.
The anti–icing air valve regulates bleed air to what pressure?
The valve regulates anti–icing air pressure to a constant 50 psi.
What is the purpose of the compressor acceleration bleed valve during engine start?
The compressor acceleration bleed system aids in compressor stall/surge prevention by allowing eighth
stage compressed air to be bled off during engine start.
Where are the bleed air valves located at?
The bleed air valves are identical and are mounted to a manifold on the eighth stage of the compressor case.
During normal shutdown, the ABC valve is in what position?
During normal shutdown, the FADECs will energize the ABC valve closed allowing the 8th stage pressure
to vent into the nacelle
What is the overall purpose of the IRS?
The overall purpose of the IRS is to deflect engine exhaust away from the fuselage and reduce the aircraft
IR signature.
What is the function of the Coanda nozzle tube?
The coanda nozzle tube entrains (creates an area of low pressure causing a vacuum effect) IRS exhaust flow and pulls the flow outboard.
How is the internal volume of the oil system broken down?
The usable oil in the tank is 1.92 gal. The unusable oil that always remains in the lines is .3 gal. It has an
expansion volume capacity of .78 to allow for thermal expansion during operations. Finally it has a .25 gal
gulping volume (represents the initial amount of oil required to fill the lubrication system lines, pumps,
sumps, bearings, etc., when the engine is started).
What is the engine oil tank pressurized to? What is the operational ceiling of the oil tank?
The tank is pressurized to 20 PSIG at sea level by the air scavenged from the air oil separator at sea level to ensure adequate delivery of oil to the engine oil pump up to 30,000 feet.
What is the scupper assembly used for?
The scupper assembly prevents catastrophic loss of engine oil in the event the oil cap is not installed
properly.
What is the purpose of the OCU?
The purpose of the OCU is to contain, cool, and filter the engine oil.
What is the purpose of the thermal lockout device on the DPI of the fuel filter assembly?
The purpose of the thermal lockout device is to prevent erroneous activation by viscous fluid below 80
degrees Fahrenheit.
When will the EMS remote impeding and actual bypass indicators actuate?
The EMS remote impending bypass indicators will signal when the pressure drop across the filter reaches
22 psid, the actual bypass indicator will extend at 30 psid.
Oil leaving the air oil separator is routed where and at what psi?
The oil is discharged back to the tank at 33 psi.
At what percent accuracy can a 500–1000 micron ferrous particle be identified by the magnetic
plug?
85 percent accuracy.
How many scavenge and pressure elements does the oil pump have?
The oil pump has seven scavenge elements and two pressure elements.
How is the speed of the engine power turbine determined?
The speed of the power turbine (LPT) is measured by the rotation of an LPT shaft mounted, speed pickup
wheel (also serving as an oil impeller) and a dual coil magnetic sensor mounted to the rear sump. The
sensor is located in close proximity to the exciter teeth of the speed pickup wheel. As these exciter teeth cut
through the field created by the sensor, an electronic signal/pulse is generated.
Where does the Np wiring harness send signals to?
The harness wiring transmits power turbine speed (Np) information to FADEC A and B harnesses.
What does the EMS provide?
It provides in-flight, ground test, and ground maintenance monitoring for engine operating limit exceedance
detection, fault detection/isolation, power assurance check, and post-flight maintenance data.
Using information from the data storage, the ground station will provide the maintainer with what
three pieces of information?
The ground station will produce inspection, service, and replacement requirements information.
What is the purpose and function of the engine vibration signal conditioner?
It is an electrical signal conditioner designed to condition the vibration signals from the three
accelerometers.
Where are the T2 and P2 sensors mounted?
8:30 and 12 O’clock positions.
How many MGT thermocouples on each engine?
14 MGT thermocouples. These thermocouples are located within the vane airfoils of the power turbine 3rd
stage vane ring.
Which MGT thermocouples are dedicated to which FADECs?
FADEC A receives signals from the even numbered positions 2, 4, 6, 8, 10, 12, and 14, while FADEC B
receives its signals from the odd numbered positions 1, 3, 5, 7, 9, 11 and 13.
When does the anti–icing air valve pressure switch actuate?
The pressure switch has an actuation set point of 15 psi for increasing downstream pressure and a reset
point of 10 psi for decreasing downstream pressure.
What does the VSLED airborne unit support?
The VSLED supports in–flight monitoring and postflight analysis of the aircraft.
What are the two cumulative damage indexes used by VSLED.
Cumulative damage index (CDI) 1 is computed for stress rupture of hot–section parts. CDI 2 measures hot
corrosion effects.
What controls engine power during normal flight operations?
During normal flight operations, the thrust control levers (TCL), (center console), pilot (left side console)
control engine power.
How is control of the engine achieved?
Control of the engine is achieved by adjusting the fuel flow and the compressor variable geometry (CVG)
vane angle.
What are the three basic goals of engine control logic?
First, it is designed to provide a closed loop control of gas generator speed. Second, it protects the engine
from exceeding operating limits. Third, it needs to start and shutdown the engine in a controlled manner.
How are the FADECs powered during start up and emergency operations?
For start up and emergency operation, the FADECs are powered by +28 VDC aircraft power.
Where is the memory stored for the FADEC that last controlled the engine?
Memory of which FADEC last controlled the engine is stored in the FADEC A.
At what Ng, will the FADEC turn on the ignition exciters?
At 2100 rpm Ng speed, the FADEC will turn on the ignition exciters by de–energizing the ignition relay in
each exciter box
After light off, the FADEC looks for what indication from the MGT thermocouples to indicate
normal operation?
An MGT residual temperature is taken when the igniter is energized and the FADEC then monitors for a
200 degree F rise above this residual temperature.
What component sends the power demand signals to the FADEC?
The FCC sends a PDS to the FADEC.
During a flame out, if a relight is not detected before the Ng drops below 85percent, what will the
FADEC do?
If a relight is not detected and the Ng speed drops below 85percent, the FADEC will initiate a controlled
engine shutdown.
During failed fixed operation, how is the engine shut down?
Engine shutdown in the fail fixed mode is accomplished by moving the ECL lever to OFF.
What is the purpose of the APU?
The APU system drives the MWGB, in turn driving components to provide electrical, hydraulic, and
compressed air for preflight checkout, operation of aircraft systems, main engine starts, and proprotor blade
fold/wing stow.
What are the characteristics of the APU gas turbine power section?
The gas turbine power section is a single shaft, gas turbine engine including a compressor/turbine assembly,
and APU combustion assembly. The compressor/turbine assembly consists of an air inlet housing, rotor
assembly, diffuser, and turbine nozzle assembly. The APU combustion assembly consists of the combustor housing, integral combustor liner, start and main fuel nozzles, and manifolds.
How are the overhung radial compressor and turbine wheel bearings cooled?
Both bearings are cooled by an air/oil mist entering through the pinion shaft, lubricating the bearings, and
returning to the gearbox sump.
What is the primary function of the APU accessory/speed reduction drive gearbox?
The accessory/speed reduction drive gearbox reduces the turbine assembly rotor speed from 64,154 rpm to 12,029 rpm to drive the MWGB and its components.
What transmits power from the APU accessory/speed reduction gearbox to the MWGB?
The hydro viscous clutch transmits power from the APU reduction gearbox to the MWGB.
Through what percentage of the APU self–sustaining speed, will the APU starter motor assist
with the acceleration?
The starter assists with the acceleration of the APU through approximately 50percent of the APU selfsustaining
speed of 100 percent
At maximum contamination, how long can the APU operate with the fuel filter?
The APU can operate for 12 hours at maximum contamination rates
What is the maximum operation in APU CRANK mode before timing out?
APU CRANK mode has a timeout feature limiting it to 30 seconds of maximum operation.
Where is the APU initiated BIT (IBIT) selected?
The APU system IBIT is selected in the MFD WRA TEST STATUS page.