GK (random) Flashcards
What is the flat rated shaft horsepower output of the PT6A-68 engine?
1100 SHP
What are the two sections of the T-6’s engine?
- Gas generation section
- Power turbine section
What components make up the gas generator section of the engine? (aft half)
- 4 Stage Axial Flow Compressor
- Single-Stage Centrifugal Flow Compressor
- Combustion Chamber
- Single-Stage Compressor Turbine
What components make up the Power Turbine section?
- 2 Stage Axial Flow Power Turbine
- Reduction Gearbox
Briefly describe the flow of air into and through the engine?
Air enters the intake cowling beneath the prop and flows first through an inertial separator. It then turns 180 deg and passes through a 4 stage axial compressor and a single stage centrifugal compressor. From there, it enters the combustion chamber, is mixed with fuel and is lit. The expanding air first passes over the compressor turbine, making the engine self- sustaining, and then passes over the two power turbines before passing through the exhaust ports and diverted rearward by the exhaust stacks.
What is the capacity of the oil system?
18.5 quarts
What components does the oil system supply filtered oil to?
- Engine Bearings
- Reduction Gears
- Accessory Drives
- Propeller
When must oil be checked and where to get an accurate reading?
Within 30 minutes of engine shutdown and using the dipstick, not the sight gauge.
When does the Amber OIL PX illuminate?
- IDLE - 15-40psi - no time delay
- >IDLE - 40-90psi - 10s
When does the Red OIL PX illuminate
IDLE - <15psi - no time delay
>IDLE - <40psi - no time delay
When does the Amber and Red OIL PX illuminate?
IDLE - 15-40psi - 5s
The engine oil pressure indicator may display oil pressures up to __ psi with the engine shut down due to the design of the oil pressure transmitter.
4
Caution: For most accurate results, check oil level how many long after shutdown?
15-20minutes
Caution: What is the only acceptable method for getting a correct indication of oil level?
Dipstick
Note: T/F Due to the sensitivity of the SCU, a single, momentary illumination of the amber OIL PX annunciator while maneuvering indicates a system malfunction.
False
The Reduction Gear Box reduces shaft output speed from ______ RPM to a propeller operating speed of ______ RPM.
Over 30,000 - 2,000
What drives the RGB?
Hot Gases impinging on the 2-Stage Power Turbine
What does a red CHIP annunciator indicate?
Contaminated oil
T or F: the RGB is mechanically connected to the gas generator section of the engine?
False - No Mechanical Connection to the Gas Generator Section
What accessories are mounted on the reduction gearbox?
- Prop interface unit (PIU)
- Torque probe
- Permanent magnetic alternator (PMA) (on top)
- Air conditioning compressor (belt driven) (on right side)
A chip detector is mounted in the RGB to detect ferrous material in the ___.
oil
The propeller system is designed to maintain a constant speed of _____ during most flight conditions?
2000 RPM (100% Np)
What is the unit on the primary engine data display that indicates prop speed?
Np
At 100% indicated torque, the engine is producing approx _____ foot pounds of torque at the prop shaft?
2,900 ft-lbs
What are the three basic conditions of propeller pitch?
- Feathered
- Low pitch (flat or fine)
- High pitch (coarse)
Approximately what is the blade angle of the propeller at low pitch?
15°
Normally, propeller governing is automatically set by the ____ and ____.
PMU and PIU
What happens to the prop if there is an engine failure with the PCL out of the CUT-OFF position?
The prop will slowly begin to feather due to loss of oil pressure but MAY NOT fully feather.
Power for the feather dump solenoid valve is provided through which circuit breaker?
PROP SYS
With the PMU functioning, the _______________ will modulate oil pressure to the prop pitch change piston to limit Np to 106%, while electronic governor will keep Np at 100%.
mechanical overspeed governor
If PMU is not functioning, the ______________ will modulate oil pressure to maintain Np at or below 100+/-2 %.
flyweight overspeed governor (checked in hammerhead)
What will happen if the PROP SYS CB is pulled, the PMU is off, and the PCL is placed in CUT-OFF?
The prop will not rapidly feather and may not fully feather until after landing
During an auto start or normal operations with the ignition set to NORM, the ____ will energize and de-energize the igniters as required.
PMU
Power for the START control is provided through a circuit breaker placarded START, located on the ________ bus circuit breaker panel in the front cockpit.
battery
During an auto start or normal operation with the IGNITION switch set to _________, the PMU will energize and de-energize the igniters as required.
NORM
Power for the IGNITION system is provided through a circuit breaker, placarded IGN, located on the _______ bus circuit breaker panel in the front cockpit.
Battery
T/F If the IGN SEL message remains continuously illuminated, notify maintenance personnel after the mission.
True
The _____ PCL is connected to the Fuel Management Unit (FMU) both electrically and mechanically with a flexible cable.
Front
T/F When the PCL is moved forward to idle during engine start, two roller bearings lock in place on the front side of a rocker cam detent to secure a gate.
Ture (This is what makes the two audible clicks when pushing the PCL up @ 60%)
What is the primary source of power for the PMU?
PMA
What sort of power does the PMA provide?
32 VAC, and the PMU converts that to DC power
When does the PMU automatically switch to 28 VDC from the battery bus?
- When the prop PRM drops below 40-50% Np
- When the PMA fails
The aircraft weight on wheels switch on the main gear struts controls what for the PMU?
PMU In Flight and Ground Mode
In ground mode, what is idle? Flight mode?
- 60% N1
- 67% N1
Above ______ feet MSL the PMU raises N1 to maintain Np above 80% to avoid stress on the propeller during spins.
10,000’ MSL
Relation of PCL position to power setting is _______ with the PMU operating.
Linear
In what situations will the PMU automatically abort the start?
- light off has not occurred within 10 seconds of selecting AUTO/RESET
- ITT exceeds 940 deg C for 2 seconds, 870 for 4 sec, or 840 for 19 seconds
- N1 acceleration rate to idle is 50% less than normal
The PMU will go offline when the IOAT exceeds _____?
121°C
When does hydroplanning occur (nose wheel vs. main wheel)?
Nose wheel: 85 kts
Main wheel: 115 kts
Tire pressure (nose & main)
Nose: 120 +/- 5 psi
Main: 185 +/- 5 psi
Until below what quantity does the fuel probe measure?
Outer probe fail: 445 ± 50 lbs
Middle probe fail: 308 ± 50 lbs
Tire wear (nose gear)
No visible cords
Main tire wear (Michelin)
Always (and local) sortie: no red cords
O+B: maximum of 3 cords
X-Country sorties: maximum of 2 cords
Main tire wear (Goodyear)
Always: no red cords
Local sorties: one white cord
O+B or X-Country: no cord visible
