NATOPS - Powerplant Flashcards by Jon Miller

Describe the aircraft powerplant.

single, non-afterburning twin-spool turbofan engine

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Describe the compressor/turbine configuration

2 stage low pressure compressor driven by a single stage LP turbine and a 5 stage high pressure compressor driven by a single stage HP turbine. N1 and N2 shafts are concentric and both rotate clockwise when viewed from the front.

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What is 100% N2 in RPM

15,512 RPM

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When does the bleed valve close and how is it indicated?

61±4%, indicated by an N2 increase of 3% and a 50 degree C decrease in EGT.

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When does the bleed valve open?

When N2 RPM falls to 45% during shutdown

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When does the bleed valve open if the engine is operating under manual fuel control?

When GTS button is pressed it opens for 60 seconds. Or when engine rpm is below 61±4% when the engine is switched to manual fuel control.

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***What is bleed air used for within the engine?

To seal the compressor and turbine bearing compartments as well as providing cooling for the turbine assemblies. Also provides engine anti-ice to spinner

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***What is bleed air used for external to the engine and what stage does it come from?

ECS, OBOGS, anti-g, and the fuel tank pressurization system; 5th stage

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When does the steam ingestion bleed valve open?

When the launch bar is not retracted, weight on wheels, and N2 RPM above 70%

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What does the ACCEL caution light indicate?

The steam ingestion bleed valve is not in the commanded position OR the shot of fuel solenoid is not operating

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How is engine anti-ice provided?

A small flow of bleed air is continuously ducted forward through the N1 shaft and through the fan spinner

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***What does the external (accessory) gearbox drive?

(HTFOG) Hydraulic pumps, 
Tach generator (N2 rpm), 
Fuel pumps (high press &amp; low press), 
Oil pumps, and 
Generator

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***What drives the engine during start?

The Air Turbine Starter (ATS) rotates the N2 shaft through the external gearbox

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What does the engine fuel system consist of?

LP fuel pump, fuel cooled oil cooler (FCOC), LP fuel filter, HP fuel pump, Fuel Control Unit (FCU), and 18 fuel spray nozzles

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When does the LP PMP caution light illuminate?

Fuel pressure drops below 35 psi

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What modes does the engine fuel control have?

NORMAL (main) and MANUAL (backup)

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What may selecting MANUAL fuel control at high rpm result in?

Exceeding RPM or EGT limits

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How is fuel metered when in manual fuel control?

By direct movement of the throttle

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What meters a fuel supply to the fuel spray nozzles during the starting cycle?

Sub-idle Fuel Control Unit (SIFCU)

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What automatically prevents overspeed and overtemp conditions under normal operation?
***Does it monitor N1 or N2?

Engine Control Amplifier (ECA)

*Monitors N1

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What is the total capacity of the oil tank and system?

25.2 U.S pints

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How many pumps does the oil system have?

One pressure, Three scavenge pumps

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When does the OIL PRESS warning light

illuminate?

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When Differential pressure decreases below 10 psi

What does the ignition system consist of?

Study These Flashcards

Two 12 joule dc ignition units and two igniters

How is ignition controlled?

Ignition is controlled by the ECA and starter control unit. Both igniters operate during ground and air starting.

***What is the function of the GTS?

The GTS provides air to start the engine on the ground, and can also be used in flight to assist during an airstart. (***provides bleed air to power the Air Turbine Starter)

Where is the GTS located?

Above the engine bay

What does the GTS consist of?

The GTS is a self‐contained unit complete with ignition system, fuel pump, fuel control, lubrication system, and a dc starter motor and consists of a compressor driven by a two stage turbine.

When does the green GTS advisory light illuminate?

Once the GTS is at idle

What happens to the GTS when the ENGINE switch is momentarily selected to START?

The GTS accelerates, the start valve is opened, the dump valve closes and the GTS supplies compressed air to the engine ATS.

What prevents shock loading of the ATS clutch?

A speed switch inhibits operation of the start valve when N2 rpm is above 20 percent

When does the GTS automatically shut down?

When N2 rpm reaches 45 percent

***What is the minimum interval for GTS start attempts?

3 minutes, then 30 minutes after 3 attempts

When do protection circuits within the starting system automatically shut down the GTS?

When GTS idle speed is not achieved within 30 seconds after the GTS start button is pressed.

How do you interrupt the start cycle?

By placing the throttle to OFF

How do you shut down the GTS after an aborted start attempt?

Placing the engine switch to OFF

***What is the basic start sequence?

(BATT switches ON, throttle OFF, Engine switches ON, Ignition NORM) - GTS start button - press momentarily ***(GTS advisory light within 20 seconds) - ENGINE switch - START (READY advisory within 15 seconds) - Throttle - IDLE when RPM is between 17-20% (light off must occur within 15 seconds) - Monitor engine instruments for normal start while engine stabilizes at idle with the OIL PRESS warning light out

***What is max EGT during a ground start?

550˚C with max over-shoot of 20˚C for 10 seconds

What is max EGT during an airstart?

600˚C with max over-shoot of 50˚C for 10 seconds

***What are the indications of a compressor stall?

loud bangs/pops, rpm drop and high EGT

***What is the danger of the bleed valve being stuck open?

Reduced thrust and high EGT

***What should idle rpm be with bleed valve closed and airflow knob not in OFF position?

55+/-2%

***What are the indications of an engine fire?

FIRE warning light, audible tone (first indications) May be accompanied by rising EGT, excessive fuel flow, erratic or rough engine operation, smoke, flames, EGT/RPM, OIL PRESS, HYD, or TP HOT warnings and cautions

***What does it mean if the fire light comes on and then goes off?

Temperature has dropped below 300 F or the fire loop was burned through

***What temp causes the TP HOT caution to illumiate?

150 F

***What causes the EGT/RPM light to illuminate?

EGT 650+/-8 F or N1 112.4+/-1%

***What should you do if your engine flames out below 1,500 feet AGL with airspeed below 180 KIAS?

Eject

***When is the Starter Control Unit energized?

When both engine switches are ON

***What are the possible failure conditions with a dual channel ECA failure?

Full trim - ECA is restricting fuel flow at all throttle settings (EGT and RPM decreases, significant reduction in thrust available, very low idle rpm) No trim - ECA is not restricting fuel flow (most likely failure mode. EGT and RPM increase)

***What is the purpose of the finger lift and what does it do?

Prevents inadvertent pull of throttle to OFF. | Raising it allows you to go below approach idle stop or go past idle to OFF

***What temperature does the engine and GTS fire loop go off at?

300 F

***Does the Sub idle fuel control unit (SIFCU) work in manual fuel control?

No. Normal only

***What does the GTS start button do?

Starts the GTS, energizes the igniters when ignition is NORM, and starts the electric fuel boost pumps. If airborne, wheels down, it also removes the approach idle stop.

After lowering the landing gear, what direction should your first throttle movement be in?

FWD in case the approach idle stop has inadvertently lifted the finger lift

***When do the igniters operate?

Automatically when the READY light comes on during start, OR manually by pressing the GTS button (in flight they operate for 30 seconds after pressing)

NATOPS - Powerplant Flashcards

(55 cards)