T-38 Systems (SO1190) Flashcards
Where are the two engine-driven generators located?
on an airframe mounted gearbox in the rear of the airplane
The generators produce ____ current when the engines are running to power the two AC busses
AC (alternating current)
How much load does each generator normally carry? How much are they capable of carrying?
Each generator normally carries one-half the total electrical load, but each generator can carry the entire AC load without an interruption in power
What converts AC power to DC power? Where do they get their power from?
2 transform rectifier units (TRUs) which get their power from the AC electrical buses
What do the TRUs power?
2 essential DC busses and one non-essential DC bus
What provides DC power when the engines are not running or the AC buses are not powered?
a 24-volt, lead acid battery
The battery provides power to the battery bus for:
SEA
Static inverter
Engine start
AB ignition
Where is external power plugged in? What can it power? What kind of current is it?
-plugged into the left aft side of the fuselage
-can power the entire T-38C electrical system
-provides AC power, which powers the TRUs to provide DC power
Where is most electrical equipment located?
in the nose section
How is electrical equipment cooled?
On the ground: electric fan
Airborne: ram air and cockpit air
What is connected to the aircraft for engine starting?
Low pressure air
What supplies electrical power for ignition?
The battery (or APU)
What supplies power to the airframe mounted gearboxes?
the engines
What is the useable capacity of fuel system?
3,906 pounds (583 gallons)
What are the ways the aircraft can be refueled?
-Single point refueling via the receptacle on the left forward section of the fuselage
-Manually using the “over the wing” procedure
How does the useable fuel change with over the wing?
Subtract 6 gallons (40 pounds) if using over the wing
Fuel is supplied to each engine by two separate systems. Each system has its own fuel indicating system. What provides connection to either engine fuel system?
A fuel crossfeed valve
How many fuel pumps are there?
Two fuel pumps for each engine
What are the kinds of fuel pumps? Which is the most essential?
An electrically powered boost pump supplies fuel under low pressure to an engine-driven fuel pump.
The engine can operate on gravity feed without the boost pump, but the engine cannot operate without the engine-driven fuel pump.
How many hydraulic systems are there and what are they?
two hydraulic systems –the utility hydraulic system and the flight control hydraulic system
Are the hydraulic systems connected and how are they powered?
The hydraulic systems are independent and powered by an engine-driven pump mounted on an airframe-mounted gearbox
What engine-driven pump controls which hydraulic system?
Flight control hydraulic system -> right pump
Utility system -> left pump
Both systems operate with hydraulic fluid from separate reservoirs and provide hydraulic power to the primary flight control surfaces. If either system fails,
the remaining system will continue to power the flight controls
What hydraulic system do the wheel brakes belong to?
The wheel brakes are powered by a separate, independent system
The utility hydraulic system operates:
FANGS
Flight Controls
Augmenter (SAS)
Nose Wheel Steering
Gear
Speed brake
What indicates an unsafe gear condition?
Red light in the gear handles, an intermittent warning tone, and blinking GEAR warnings on the HUD/MFD
Does the alternate landing gear lowering system require hydraulic pressure or electrical power?
No. The release handle extends the gear by gravity with the aid of the airstream
When will nosewheel steering NOT operate?
-no weight on the nosewheel
-either start button pressed
-either AB selected
How is the stability augmenter engaged and what does it do?
The stability augmenter is engaged with the EGI switch on the Avionics Activation Panel (AAP) and a yaw dampener switch.
Its purpose is to stabilize the aircraft about the vertical axis
How are the flight controls operated? How are they interconnected?
Hydraulically-operated flight control systems. The control stick and rudder pedals are mechanically interconnected between the two cockpits
Each wing flap is powered by a
separate electric motor; the flaps are interconnected so if one motor fails, the other motor actuates both flaps
What is used to pressurize and air-condition the cockpits?
Bleed air from both engines
When does cockpit pressurization occur?
Automatically when the canopies are closed and locked
The front canopy can withstand a bird strike of
4 pounds from 125-400 knots
What systems are in the FCP only?
-Batt and Gen switches
-Fuel shutoff switches, boost pump switches, crossfeed switch
-Throttle gate, anti-ice, and cutoff
-pitot heat, cabin air temp, defog
-alternate gear extension
-all external lighting
-weapon switches
-UHF, NAV, TACAN backups
Avoid taxi operations with an open canopy with relative wind greater than ____ knots
30 knots
What things are on the airframe mounted gearbox?
AC generator and hydraulic pump
Electrical power for the T-38C is primarily provided by
two AC generators
Where is most of the electrical equipment housed?
Nose section
What is powered by both hydraulic systems?
the flight controls
On landing rollout after a full stop, when may you engage the nosewheel steering?
when below 65 knots
You are taxiing into a 20-knot headwind. How fast may you taxi with the canopy open?
30 knots
You are flying a zero-G pushover. Due to engine oil supply and pressure requirements, do not exceed ____ in this attitude
10 seconds
While solo you notice a fuel imbalance. This could lead to CG (center of gravity) problems if
the right system contains more than twice the left
During the engine run-up for takeoff, your right engine RPM reads 96%. You should
abort the takeoff and write it up
What is the cut in range for the generators?
43-48% RPM
What normally provides all AC electrical power in the T-38C when the engines are operating?
Two, three-phase AC generators
What is the voltage output of the generators?
115/200 Volts
How many cycles per second do the generators output?
320 - 480 cycles per second
Where are the generators located and why?
The generators are on an airframe mounted gearbox.
This maintains the frequency of the AC voltage within limits throughout the entire range of engine RPM
Each generator is run by its respective airframe mounted gearbox that shifts at ___ to ___ % engine RPM.
65 to 75%
this keeps the generator RPM and frequency output within rated limits
Under normal conditions, each generator carries about ___ the total electrical load.
1/2 the total load
What does moving the generator switch to OFF do?
The OFF position does not stop the generator from spinning, but disconnects the generator output from its bus
What protects the AC electrical system from a faulty generator and protects the generator from a faulty bus?
The Protection Panel
When external power is connected, what systems are energized?
all AC and DC buses (via the TRUs)
What must be on to receive external power?
Battery Switch
What is the static inverter?
it supplies AC power for starting either engine on the ground or in flight.
In addition, it operates the right engine AC sensors, both fuel quantity sensors, the oxygen quantity indicator, and flight hydraulic pressure gauge
How is the static inverter powered?
by the battery bus to convert DC into AC
How do you activate the static inverter?
-Pushing either start button
-moving either throttle into AB range
-holding the fuel/oxygen check switch
To give accurate and immediate indication of engine performance, AC-powered instruments are used. These are:
oil pressure, fuel flow, hydraulic pressure, fuel quantity, and oxygen quantity
What are the indications of a generator failure with good crossover?
-MASTER CAUTION
-GENERATOR light
the other generator picks up the total load
Why would there be no crossover after a generator failure?
If a generator fails, the remaining generator generally picks up the load. If there is a bus fault or a problem with the crossover relays, you may not get a crossover.
What are the indications of an airframe mounted gearbox failure?
-MASTER CAUTION
-GENERATOR
-Hydraulic lights
What are the indications of a Gearbox Failure to Shift? Why does it happen?
-GENERATOR
The gearbox failed to shift when a throttle is moved forward or aft through 65% to 75% RPM
What does the landing-taxi light switch control?
the illumination of the dual filament light (only if it turns on)
What do you need to do to extend the landing light?
Turn on position light and lower the gear
When does the hydraulic light illuminate?
when pressure drops below 1,500 psi or during an overtemperature
When does FUEL PRESSURE illuminate?
when line pressure drops below 6 psi (normal is 10 psi)
When does the OXYGEN light illuminate?
at or below one liter
When does FUEL LOW illuminate?
Illuminates after a 7.5 second delay when either indicator reads below 250 pounds
When does XMFR RECT OUT illuminate?
When there is a possible failure of both transformer-rectifiers. The battery powers both essential DC busses and should last approx. 15 mins if fully charged
When you lose a generator in the T-38C,
the other generator normally picks up the load
The ____ normally supplies power to the DC busses when an engine is operating.
transformer rectifier units
If the left airframe mounted gearbox fails,
-the LEFT GENERATOR light will illuminate
-the utility hydraulic light will illuminate
Which of the following are powered by the static inverter?
Both fuel quantity indicators (on EED)
What must you do to extend and illuminate the landing-taxi light?
-turn on the position light
-extend the gear
-turn on the landing light switch
If the MASTER CAUTION light and RIGHT GENERATOR light illuminate, how can you determine if the left generator is not powering the right AC bus?
-check for blank HUD
-check for OFF indications in the right oil pressure and fuel flow indicators, and on both fuel quantity indicators
In the event of complete AC power failure,
the flood lights with illuminate provide the flood light control knob is out of the OFF position
The Caution Light Panel may be operated in the DIM provided
a. the instrument rheostat is _____
b. the Caution light BRIGHT/DIM switch is momentarily moved to the ____ position
c. there is ____ power available
a. OFF
b. DIM
c. AC
At what RPM should the generators come online?
43-48% RPM
How are the Warning/Caution/Advisory System lights powered?
By an essential DC bus in all conditions
What is used to convert AC power into DC power?
two Transform Rectifier Units (TRUs)
If both TRUs fail, what will pick up the DC load on the two essential DC busses?
the battery
A single TRU failure generates what advisories?
-PFL fault
-AVIONICS alert
The battery will power the two essential DC busses for approx.?
15 minutes
When the battery switch is turned on, a minimum voltage is required to connect to the essential DC busses. How many volts does it take to close the battery relay?
18 volts
If the battery relay will not close, the battery will not connect to the DC busses and will not charge even if the engines are running or if external power is connected. Therefore the pilot must check the battery has at least ____ before applying APU ***
18 volts
When are the 3 times battery power is required?
- During starts when an APU is not used
- When both TRUs fail
- When both generators are inoperative
What are the DC-powered instruments? ***
-standby attitude indicators
-the vibrator in the standby altimeters
-flap position indicators
-MFD
-EED
Where is the fuel stored in the T-38?
in the fuselage behind the rear cockpit in five rubberized nylon bladders
Why are the fuel tanks referred to as “left” and “right”?
The two systems are referred to as left and right fuel systems because of the particular engine each supplies, not the physical location of the fuel cell
Which are the left fuel system cells?
The forward fuselage cell and the forward and aft dorsal cells
What are the right fuel system cells?
The center and aft fuselage cells
How is the aircraft normally refueled?
via single-point system which provides fuel simultaneously to both systems
If you cannot use the single-point system, you can manually refuel the aircraft “over-the-top.” What is the drawbacks?
The manual refueling provides 40 pounds less usable fuel.
Also, ensure the left (forward) system is filled first to prevent a center of gravity shift aft.
The fuel cells hold up to ____ of useable fuel
3,906 pounds
How many capacitance probes are there in the fuel system? What do they do?
The fuel cells contain seven probes. The left and right fuel systems have an AC sensor to interpret and display the fuel quantities on the EED
Fuel quantity indicators on the EED indicate the amount of usable fuel in ___ pound increments
10-pound increments
Where is the common vent system exit port?
located on the vertical stabilizer above the rudder
What is the pressure relief valve?
it opens to relieve any excessive pressure buildup in the fuel cells due to thermal expansion
What are the check valves?
they prevent the loss of fuel through the vent line during normal aircraft maneuvering or changes in ambient temperature
Each fuel system has a single AC-powered fuel boost pump that provides fuel to an engine-driven fuel pump. What does the boost pump do?
provide fuel under pressure to the engine-driven fuel pumps
Where are the boost pumps located?
In the forward and aft fuselage cells in an inverted flight reservoir
What are the inverted flight reservoirs?
They are designed to trap a small amount of fuel during inverted or negative-G flight to maintain fuel flow to the engines for a limited time
How are the boost pumps controlled?
Two On-Off boost pump switches only located in the FCP
What do the rear cockpit boost pump lights do?
They illuminate when either boost pump switch in the FCP is switched to OFF. They do NOT illuminate with a boost pump failure
What does the crossfeed switch do and when is it used?
The crossfeed switch connects the right and left fuel systems. Fuel system crossfeeding is only used to correct fuel imbalances greater than 200 pounds
Can you use crossfeeding to transfer fuel from one system to the other?
No. You cannot use crossfeeding to transfer fuel
What are the fuel shutoff switches?
DC-operated, controls fuel flow from the boost pump to the engine
When would you use the fuel shutoff switches?
During normal operations, fuel shutoff valves are controlled by the throttles (placing the throttles to OFF also mechanically shuts off fuel at the main fuel control)
Only use the fuel shutoff switches in an emergency situation, since damage to the engine-driven pumps may occur
Each fuel system has a replaceable fuel filter to separate any impurities before it reaches the engine. What happens if the filter becomes clogged?
The filter system has a bypass capability to allow fuel to flow to the engine if the filter become clogged
How do you know a fuel bypass occurs?
A red indicator extends from the fuel drains on the underside of the fuselage (found during the walkaround)
What does the fuel pressure sensing switch do? What is normal fuel pressure?
Fuel pressure sensing switch closes when there is a loss of fuel pressure in the line. Normal fuel pressure is 10 psi
When does the FUEL PRESS light illuminate?
Less than 6 psi
When does the FUEL LOW light illuminate (and time associated)?
EITHER fuel quantity indicator reads 250 pounds or less. There is a 7.5 second delay to prevent momentary activation due to sloshing
When does the fuel system display a plus (+) indicator with the greater amount of fuel?
If a fuel imbalance of 60 to 190 pounds develops b/w the two fuel systems
When is a fuel imbalance difference displayed in red?
An imbalance of 200 pounds or more
When is a magenta line shown on the EED?
When the crossfeed switch is in the ON position
How is increased fuel flow in afterburner displayed on the EED?
It is not displayed
What increments are used for fuel flow?
20 pound increments
What will the fuel flow indicators read without DC power?
Without DC power, both fuel flow indicators display zero
(T/F) The fuel crossfeed is normally used to transfer fuel from one system to the other for a fuel imbalance greater than 200 pounds.
False. You cannot actually transfer fuel between the systems using crossfeed
The right/left fuel boost pump light on the rear cockpit fuel panel illuminates when
the fuel boost pump switch in the front cockpit is turned OFF for that system
(T/F) Placing either fuel shutoff switch in the CLOSED position electrically shuts off the fuel flow to that engine at the main fuel control unit when the respective throttle is placed OFF.
False. The throttle does NOT need to be in OFF??
The left or right fuel pressure light on the caution panel illuminates when the fuel pressure sensing switch closes due to
loss of fuel pressure (below 6 psi) to that engine
Any fuel flow fluctuation limits must?
remain within steady state limits
Without boost pump pressure, the fuel is gravity fed to the engines. Gravity flow is normally sufficient to maintain MAX power from Sea Level to ____ feet MSL. However, gravity flow is only guaranteed to ____ feet MSL.
25,000 feet MSL
6,000 feet MSL
You should NOT perform MAX thrust dives with less than ___ pounds of fuel in either system
650 pounds
MAX thrust flight at zero or negative G-loads should NOT exceed ___ seconds at _____ feet or ____ at _____ feet
10 seconds at 10,000’
30 seconds at 30,000’
With 250 pounds or less in either system (FUEL LOW light), you should?
Maintain a slightly nose-up attitude if possible
do NOT allow the right fuel system to equal more than ___ the left fuel system during solo flight to avoid exceeding the aft Cg limit of the aircraft
TWICE
When is differential power method recommended?
Low altitude or with 250 pounds or less in either system
During normal operations, crossfeeding is recommended when the fuel difference exceeds ____ pounds
200 pounds
What are the steps for crossfeeding?
- Turn the crossfeed switch ON
- “pick on the little guy” turn the BOOST PUMP of the smaller tank OFF
What could cause the fuel pressure caution light to come on?
-Fuel leak
-Boost pump failure
-Partial generator failure
If an internal EED failure prevents the display of either fuel system, what happens to the solid white bar on the fuel quantity scale?
It blanks (DC dies)
What engines are on the aircraft? How much thrust do they produce?
two General Electric J85-GE-5R/S series, eight stage, axial-flow, turbojet engines
2,200 pounds at MIL and 3,300 pounds at MAX
What do the thermocouples do?
mounted on the diffuser casing, the thermocouples receive DC voltage to interpret and display EGT. The other element provides a temperature signal to the T5 amplifier for nozzle positioning
What controls the position of the nozzles during normal throttle operations from IDLE to 97%?
A hydromechanical scheduling system which senses engine fuel pressure (throttle position) to open and close the nozzles
The nozzles continue to close down until reaching the maximum EGT of ___ to ____, which occurs at about ____% RPM. Above this point, the ____ system begins to function to keep EGT in limits
630 - 650 ºC
97% RPM
T5 system takes over
Is the T5 powered by the aircraft electrical system?
No. It is powered by its own alternator, which is one of the engine accessories
The function of the _____ is to direct the flow of air into the first stage compressor blades at the proper angle
front frame
How many stages is the compressor section?
Eight stages that form a convergent duct that compresses and accelerates the air rearward
Low pressure air from an external starting unit is directed against the ____ to rotate the engine for ground starts
turbine rotors
The afterburner augments the engine thrust from approx. ___ to ___ percent
10 to 50 percent??
High-pressure bleed air from the ____ section of the engine is routed through tubes mounted on the main frame to the engine anti-ice and aircraft pneumatic system
compressor
What does the variable geometry system consist of and what do these things do?
Variable inlet guide vanes: automatically adjust to direct air into the first stage compressor blades at an optimum angle
Bleed valves: prevent overpressurization by allowing compressed air to escape at low engine RPM
What happens when you turn on the engine anti-ice system?
Hot bleed air from the eighth stage compressor is directed to the anti-ice manifold and bullet nose of the engine
Effective anti-ice requires a minimum of ___% RPM
80% RPM
Below ___%, the anti-ice system is always on, regardless of whether the system is turned on. The system is designed to fail to ___
65% RPM; system is designed to fail to ON
When the anti-ice system is on, expect a loss of 180 +/- 10 pounds of thrust; therefore, only use engine anti-ice when required. Also, do not fly in?
Known or reported icing conditions since the T-38 engines are very susceptible to damage
What does each fire light bulb correspond to in the engine?
the right FIRE light bulb is the aft detection circuit and the left FIRE light bulb is the forward detection circuit (RALF)
What is the primary purpose of the air bleed valves?
allow compressed air to escape to prevent compressor stalls at low RPM
When the engine anti-ice system is ON, hot bleed air from the eighth stage compressor is directed to the anti-ice manifold (inlet guide vanes) and the ____ of the engine
bullet nose
The ____ and ____ are both mounted on the same drive shaft as the oil pump in the engine accessory gearbox
tachometer generator and T5 generator
What should happen with the FIRE lights if an overheat condition is detected in the aft area of the left engine?
BOTH bulbs in the left FIRE light illuminate steady
Failure of a fire light to illuminate when testing the circuit means you should consider any subsequent illumination of that fire light a false fire?
No. Illumination of a fire light still warrants a fire condition, even if it did not illuminate during testing
(T/F) The tachometer (RPM) has its own generator and operates independently from the aircraft electrical system
True
What does “latching” refer to?
The letters remaining red after limits have been exceeded
The T-38 has ____ independent hydraulic power supply systems. What are they?
two;
utility hydraulic system
flight control hydraulic system
Each hydraulic system operates on approx. ____ psi
3000 psi
How is hydraulic pressure being supplied?
Hydraulic pressure is supplied by the hydraulic pump on the airframe mounted gearbox of each engine
Which engine supplies pressure for which hydraulic system?
Left engine -> Utility
Right engine -> Flight controls
What is the normal operating range of the hydraulic pressure?
2850 to 3200 psi
Does failure of the gearbox to shift affect the hydraulic system?
No. The hydraulic pump can operate on either of the two different airframe mounted gearbox speeds
The hydraulic pressure indicator is a(n) AC/DC powered indicator?
AC powered
What are the minimum and maximums for hydraulic pressures?
1,500 psi
3,200 psi
When does the hydraulic system warning light come on?
1,500 psi or fluid overtemperature
When does the hydraulic warning light go out?
increasing through 1,800 psi
How do you know if you have a hydraulic fluid overtemperature?
Whenever the hydraulic light illuminates, check the gauge. If the gauge reads normal or high pressure, you have a fluid overtemperature
What are the indications of a high hydraulic pressure condition?
The only warning is the reading on the indicator itself. The caution light does not illuminate for high pressure
What does the utility hydraulic system pressurize?
FANGS
Flight controls
Augmenter
Nosewheel steering
Gear control
Speed brake
How do you “feel” the flight controls?
You cannot feel actual aerodynamic forces on the flight control surfaces b/c they are hydraulically-powered. An artificial system of springs and bob weights simulates feel. The bobweight simulates the G-load.
How does the flight control trim system work?
Trim is part of the secondary flight control system. It uses AC-powered motors to change the control stick position and neutral reference point of the artificial feel springs. The trim switch activates the servo valves with move the flight control surface to a selected position,
What are limit switches in the trim system?
Limit switches limit the range of stick travel
What are cutout switches in the trim system?
Interrupt horizontal tail trim inputs when stick force is applied against the direction of trim
What needs to be on for the rudder trim to function?
only operational when the Stability Augmenter System (SAS) is functioning and the yaw damper switch is in the YAW position
Manual rudder trim is limited to
+/- 2 degrees
How long does extension and retraction of the landing gear take?
6 seconds
When does the gear warning system beep?
The gear is not down and:
-Less than 210 knots
-Below 10,000 feet
-BOTH throttles less than 96% RPM
What does the alternate release handle do?
Allows extending the gear without hydraulic pressure or electrical power
How long does alternate gear extension take?
Usually 15 seconds, but up to 35 seconds
When is nosewheel steering deactivated?
-one or both throttles in MAX
-either start button is pressed
-when aircraft weight is not on the nose gear
Each hydraulic reservoir is pressurized by _____ to aid in the flow of fluid to the hydraulic pump and to eliminate foaming and air in the hydraulic fluid caused by altitude changes
bleed air from the compressor
Which of the following operates ONLY by the utility hydraulic system?
A. Trim system
B. Speed brake
c. Wheel brakes
D. Wing flaps
B. Speed brake
(T/F) If the engine mounted gearbox fails to shift, the hydraulic pump on that gearbox will drop off line and hydraulic pressure from that pump will be lost
False
The hydraulic caution light illuminates when either a fluid overtemperature condition is detected or the pressure drops to ____ psi or less
1500 psi
If one hydraulic system has zero pressure, be aware that hydraulic fluid may transfer from the other system, which could limit flight time to ____ minutes
35 minutes
What must you do if you lose both hydraulic systems?
Eject
What do you do if dual gearbox failure occurs?
do NOT delay your decision to eject
If you get a “Utility hydraulic” light with good indication on hydraulic pressure, is it likely?
fluid overtemperature
If you get a generator failure with a hydraulic failure, it is likely?
Gearbox failure
(T/F) The utility/hydraulic caution light will illuminate when the pressure drops to 1,500 psi or less, or is grater than 3,200 psi.
FALSE. You will not get a light for high hydraulic pressure
