Dash 1 Section 1 Flashcards
What kind of aircraft is the T-6A?
A single engine, two-place (tandem), pressurized, low-wing training aircraft made by Beechcraft and approved for day or night VFR and IFR flight
What is the T-6A powered by?
Pratt and Whitney PT6A-68 free turbine turboprop engine with a Hartzell four blade prop
What type of landing gear does the T-6 have?
A retractable tricycle type which is electrically controlled and hydraulically operated
What is the definition of max abort speed?
The maximum speed at which you can bring the aircraft to a stop in the remaining runway.
What is the definition of max braking speed?
The speed at which maximum braking effort will bring the aircraft to a stop without exceeding the maximum brake absorption energy (3.96 million ft-lbs).
What type of engine is the PT6A-68?
A reverse-flow free-turbine turboprop engine
How much thrust does the PT6A-68 produce?
1100 SHP, 2900 ft lbs torque, 2750 lbs of thrust at SL
What are the three engine sections?
The gas generator, the power turbine and the reduction gearbox
What is the capacity of the oil system?
18.5 US quarts
What are the oil system components?
Pressure, scavenge, cooling and breather
Describe airflow’s movement through the engine.
Rearward through intake duct–>through inertial separator–>annular plenum case–>four stage axial compressor and centrifugal compressor–>through diffuser tubes and straightening vanes–>combustion chamber–>ignited gases drive single stage gas gen turbine which drives compressor–>two stage power turbine drives reduction gearbox–>ejected out exhaust stacks
What is the diameter of the prop?
97”
How long is the aircraft from nose to elevator?
33’ 4”
How long is the T-6 from wingtip to wingtip?
33’ 5”
How wide is the horizontal tail?
11’ 4”
How tall is the T-6 from the ground to the top of the vertical tail?
10’ 8”
When must oil level be serviced?
Within 30 minutes of engine shutdown
For most accurate results check the oil level when?
15-20 minutes after engine shutdown
Describe the oil pressure system.
Two oil pickup elements, one in the center of the tank and another which picks up oil near the top of the tank in inverted flight.
Describe the oil scavenging system.
Two dual element gear type pumps, one inside and one outside of the accessory grbox which return scavenged oil from the bearings and gearbox and routes scavenged oil through the oil cooler
The engine oil pressure indicator may display oil pressures up to what with the engine shut down?
4 psi
When does the red OIL PX annunciator go on?
Either when oil pressure is at or below 15 psi at IDLE, when oil pressure is between 15 and 40 psi at IDLE for more than 5 seconds, or when oil pressure is below 40 psi above IDLE
When does the amber oil PX annunciator go on?
Either when the oil pressure is between 15 and 40 psi at IDLE or between 40 and 90 psi for 10 seconds above IDLE
The reduction gearbox reduces power turbine output shaft speed of what to propeller operating speed of what?
30,000 RPM; 2,000 RPM
Describe what components are mounted on the reduction gearbox.
A chip detector; propeller interface unit (top), torque probe (top), and permanent magnet alternator (top); air conditioning compressor (right side)
100% torque is available between which two altitudes on a standard day?
Sea level to 12,000’-16,000’ MSL
What controls the propeller pitch?
The PMU and PIU
What are the 3 basic conditions of prop pitch and what do they represent?
Feathered, low pitch for low speeds and low throttle settings, high pitch (between feather and low pitch)
When at low pitch the prop blade angle is approximately how many degrees from the reference plane?
15
How does the PIU/PMU control prop pitch?
The PMU sends a signal to the PIU which varies the oil pressure in the prop shaft through a transfer sleeve. Pressurized oil forces a piston forward which makes the pitch lower (more fine) or reduces oil pressure which drives a piston backwards and makes the pitch higher (more coarse)
With the PMU functioning the mechanical overspeed governor limits Np below what?
106%
The electronic governor with the PMU on will keep the prop functioning at what?
100%
The mechanical fly weight overspeed governor keeps Np at what with the PMU off (think overspeed governor check)?
100+/-2%
How does manual governing work?
The centrifugal force moves counterweights outwards causing oil pressure to dump and the feathering spring to make the pitch higher (more coarse) to keep Np in limits.
What are the two methods to feather the prop and how do they work?
- Engine shut down with PMU NORM
- Placing the PCL to cutoff
The PMU sends a signal to the prop servo valve to drain prop oil pressure
The PCL to OFF activates micro switches that power the feather dump solenoid valve which drains prop oil pressure.
When will the PMU abort a start (specific parameters)?
- If no light-off within 10 seconds of AUTO/RESET with the STARTER switch
- If ITT exceeds 940 deg C for 2 seconds, 870 deg C for 4 seconds, or 840 deg C for 19 seconds
- If N1 acceleration rate to IDLE is 50% of normal.
What five parameters may cause the PMU to abort a battery start attempt?
High IOAT; high ITT; weak battery; tailwind; high density altitude
What powers the PMU?
The PMA
The PMA supplies how many volts to the PMU?
32 VAC
The PMU automatically switches to the 28 VDC battery bus when what?
When prop RPM drops below 40-50% RPM or when the PMA fails
What controls whether the PMU operates in flight or ground mode?
The weight on wheel switches
What does it mean if an EDM FAIL message appears on the lower portion of the EID screen?
EID is not receiving all data in proper format; only the dashed out parameters/missing pointers are invalid.
What is the only signal which is processed before going to the AEDD?
Torque