Powerplant Flashcards
some stuff in here you don't need to know
What engines is the Hawker 900XP equipped with?
2x Garrett/Allied Signal/Honeywell TFE 731-50R’s
General overview of the TFE 731-50R’s:
Dual spool, axial flow, turbofan engines
How much thrust does the TFE 731-50R produce, and to what altitude?
Each engine produces 4,600 lbs of thrust, flat rated up to an altitude specified in the AFM
What is the bypass ratio at low altitudes? High altitudes?
80% bypass, 20% core at low altitude
20% bypass, 80% core at high altitude
What is the purpose of the fan, and what drives it?
Moves large volumes of air into the bypass duct and engine core, driven by the low pressure spool (N1)
What is the Low Pressure Spool (N1)?
Consists of a four-stage, low pressure axial flow compressor and three-stage low pressure turbine mounted on a common shaft
What is a stage?
A paired rotor and stator
What is one of the functions of the low pressure spool (N1)?
Increases pressure through the compressor stages without significantly increasing the velocity of the air
What is the High Pressure Spool (N2)?
Single-stage centrifugal compressor driven by a single-stage turbine on a concentric shaft
What drives the accessory gearbox, and how?
The High Pressure Spool (N2) through a tower shaft
What is a spool, and how many on the TFE 731-50R?
A compressor with a power turbine - 2 on the TFE 731-50R
Describe the combustion can:
Contains the igniters (at the 6 and 7 o’clock positions), with fuel atomizers
What does the turbine section consist of?
Contains four turbine wheels (1 high pressure, 3 low pressure) and four stator assemblies, as well as a mixer nozzle that mixes core and bypass air before the air is discharged by a convergent-divergent nozzle
How is Interstage Turbine Temperature (ITT) measured?
Thermocouples in the gas path between high-pressure turbine and first stage of low pressure turbine, sending signals to cockpit indicator and fuel computer. Each engine has own indicator on center instrument panel display
What is driven by the accessory drive?
Starter-generators*, hydraulic pump, alternator, fuel pump, fuel control unit, oil pump
What does the engine oil system contain?
Oil tank and sight gauge, oil pump, oil filter and bypass valve, air/oil cooler and bypass valve, fuel-to-oil cooler, oil-to-fuel cooler, breather pressurizing valve, & pressure and temperature transmitters and indicators
What drives the oil pump?
Accessory drive
What collects oil and returns oil to the reservoice?
Scavenge pump
What is the function of the bypass oil filter? Is there an annunciator?
Prevents contaminants from going to engine components - condition indicated in rear equipment bay… if there is a clog causing a drop in oil pressure, bypass can open, routing oil around the filter to the engine components. There is no oil filter annunciator
How is oil and fuel temperature transferred between each other?
Fuel heater provides fuel-to-oil heat transfer, air/oil cooler after fuel heater cools the oil
When does the OIL 1/2 LO PRESS annunciator illuminate?
If oil pressure drops below 49 psi on an engine
Can the ignition system be continuously operated? If so, how?
Yes - place the switch to ON
What does the AUTO switch position do in the ignition system?
Energizes igniters if there is an uncommanded N2 drop of 500 RPM
What does the fuel control system consist of?
Fuel pump assembly, hydromechanical fuel control unit, digital electronic engine control (DEEC), fuel flow divider assembly, fuel atomizers
What provides high pressure fuel to the fuel control unit, and what powers it?
Engine-driven fuel pump on the accessory gearbox
What is the function of the bypassable fuel filter? Is there an annunciator?
Prevents downline contamination of fuel - yes, there is an annunciator illuminated if the bypass is open (will illuminate around 6-8 psi, bypass will open around 9-12 psi)
What is the DEEC and its function?
Digital Electronic Engine Control, aka fuel computer. Provides governing, limiting, and scheduling of fuel during acceleration and deceleration
What is the position of the ENG CMPTR switches in normal operation?
AUTO position
How is the DEEC powered?
28 volt DC power from the PE bus
What inputs does the DEEC monitor?
Engine inlet pressure, engine inlet temperature, ITT, N2 speed, N1 speed, thrust lever angle
What are the protections offered by the DEEC?
Commands engine shutdown if N1 exceeds 107%, or N2 exceeds 107.7% (ultimate overspeed protection)
What happens if the DEEC malfunctions?
Fuel Control Unit automatically switches to manual mode
What does a red ENG 1/2 CMPTER annunciator indicate?
Total failure of engine computer, requires memory items
What does an amber ENG 1/2 CMPTER annunciator indicate?
Internal fault; ultimate overspeed protection still available; no further crew action require
What does an amber ENG 1/2 CMPTER MM annunciator indicate?
Internal fault, reversion to Manual Mode made. Crew action: place ENG CMPTER switch to OVSP PROT, resulting in ultimate overspeed protection being available again
What does a white ENG DEEC MINOR annunciator indicate?
Minor fault, complete engine control maintained; no further crew action required
How do the thrust levers control power output?
Connected to the FCU via cables and pulleys, movement drives position of FCU, causing the DEECs to send signals to the fuel controllers to increase or decrease fuel flow
With the computer switches in the OFF or OVSP PROT positions, what do the thrust levers do?
Directly control engine power through fuel control governor
What controls the fuel shutoff valve and locks the throttles?
HP Cocks
What do the HP Cocks do when closed?
Mechanically locks thrust levers in the full idle position
What is the function of the engine synchronizer?
Compares N1 or N2 of master engine (left) to provide a trim signal to the DEEC
What are some requirements of the engine synchronizer?
Requires both computers to be in AUTO position, inoperative with APR armed
What is the Automatic Performance Reserve (APR)?
May allow an automatic increase in engine thrust in the event of an engine failure
What triggers APR activation in AUTO mode?
An uncommanded split in N2 occurs of 15% or more
What does the override mode on the APR do?
Manually increase thrust on both engines or to activate system if not armed
What are some limitations of the APR system?
No increase of thrust if ambient conditions are such that the engines are N1 RPM limited (basically will not exceed engine limitations)
What is the function of the thrust reversers?
Can be used to aid in deceleration or to control taxi speed
What does an amber REVERSER annunciator indicate in flight? On the ground?
In flight: thrust reversers are unlocked
On the ground: rudder bias system is not inhibited
What is the maximum takeoff thrust with APR operating (in % RPM)? Maximum ITT? Time limit?
N1 100%, N2 101%; 1022°C Max ITT; 5 minute time limit
What are the Hawker start procedures and callouts?
- Start (engine start button activated)
- N2 (Connected to starter-generator via tower shaft… at 12% N2, & some N1 rotation, no call but HP Cock UP)
- Ignition
- Fuel Flow
- ITT
- N1
- Oil (at 49 psi)
How is maintenance scheduled?
At 6000 hours: Compressor Zone Inspection
At 3000 hours: Major Periodic Inspection
The powerplant classification on Hawker 900XP series aircraft is:
Two-spool turbofan
When the aircraft is static on a standard day at sea level, each engine develops:
4,660 pounds of thrust
The primary overspeed rpm-limiting device on the 731 series engine is the:
Mechanical governor in FCU
The maximum HP rotor (N2) overspeed is:
102.5% for 10 seconds
The maximum oil pressure for power at or above idle rpm without a time limit is:
80 psi
The maximum interturbine temperature for engine starting or relight is:
994°C
The maximum transient oil pressure permissible is:
100 psi
If the MWS reverser annunciator illuminates during the deploy cycle, it indicates:
Rudder bias not inhibited
To facilitate an accurate setting of climb power:
CLIMB in green displayed on the MFD engine display
The APR system is available:
To any engine with an operative computer
