Airline Interview Study Guide - Flashcards

Comprehensive flashcards covering turbine engine theory, aircraft systems, Part 121 regulations, aerodynamics, and airport operations based on lecture notes.

What is the basic operating principle of a turbine engine?

Intake, compression, combustion, and exhaust. Intake air is compressed, delivered to the combustion chamber where fuel is ignited, and the resulting expanding gases drive turbines that sustain the process by driving the compressors via a shaft.

What are the primary sections of a turbine engine?

Inlet, Compressor, Diffuser, Combustor, Turbine, and Nozzle.

How does a centrifugal-flow compressor increase pressure?

It slings air outward toward the edges of the turbine into a diffuser, which slows the air via a divergent pathway, trading velocity for pressure.

Describe the components and function of an axial-flow compressor stage.

Each stage consists of a spinning rotor blade and a stationary stator vane. Rotor blades push air rearward and stator vanes slow the air down to trade velocity for pressure.

What is the primary power setting reference during takeoff, cruise, and approach in a dual-spool engine?

N1, which refers to the rotational speed of the low-pressure spool.

What is the N2 spool and why is it used during engine start?

N2 is the high-pressure compressor/spool. It is used during start because adding fuel, ignition, and disengaging the starter are based on N2 RPM.

Which engine components are driven by the N2 shaft via the accessory gearbox?

Integrated drive generators, hydraulic pumps, oil pumps, and fuel pumps.

Where is the point of highest pressure and lowest velocity in a turbine engine?

At the diffuser discharge/combustor inlet.

What is the definition of a turbofan engine?

A turbojet core with a shrouded fan at the front (driven by N1) that accelerates a larger mass of air to a slower velocity, where most thrust is generated by bypass air.

What is the bypass ratio of the CRJ-200 engine?

$$6.2:1$$

Why is jet fuel measured in pounds rather than gallons?

The energy content of fuel is proportional to its weight, and the volume of a given weight of fuel varies greatly with temperature.

What is the function of the Variable Geometry (VG) system?

It optimizes the angle of attack of airflow at the compressor blades and regulates airflow across the N2 compressor by changing the position of inlet guide vanes and stator vanes via FADEC.

What is Engine Pressure Ratio (EPR)?

The ratio of engine output pressure to engine intake pressure.

What does ITT stand for and what does it measure?

Interstage Turbine Temperature; it measures the temperature of gases between the low-pressure and high-pressure turbines using thermocouples.

What causes a 'Hot Start' in a turbine engine?

Fuel is introduced and ignited at too low of a compressor RPM, resulting in inadequate pressure in the combustion chamber and fuel burning at a very high temperature with little gas flow.

Define a 'Hung Start'.

The engine starts after fuel is introduced but fails to reach ground idle RPM, leading to insufficient airflow and very high temperatures.

What are the signs of a compressor stall?

A loud bang with flames emitting from the front and back of the engine, followed by vibrations and a rapid increase in EGT.

What are the sources of bleed air on an aircraft?

External air source, Auxiliary Power Unit (APU), and the main engine high-pressure compressor.

From which stages of the CF34 engine is bleed air extracted?

The $6^{th}$ and $10^{th}$ stages.

What is 'Maximum Differential' in a pressurization system?

The maximum ratio of cabin pressure to outside air pressure that the system can sustain.

What do 'Squat Switches' (Weight on Wheels) ensure regarding pressurization?

They ensure the cabin is depressurized when the aircraft is on the ground.

What is the hydraulic formula derived from Pascal's Law?

$$\text{Force} = \text{Pressure} \times \text{Area}$$

Where does the air used for the Air Cycle Machine (ACM) come from?

Main engine bleed air, APU bleed air, or ground air.

Under Part 121, what is the required takeoff alternate distance?

Within 1 hour from the departure airport at normal cruise speed with one engine inoperative.

What is the '123 Rule' for destination alternates?

An alternate is not required if, for 1 hour before to 1 hour after ETA, the forecast ceiling is at least $2000\,ft$ and visibility is at least $3\,sm$.

What equipment is required for RVSM operations?

Two independent altitude measurement systems, an altitude alerting system, an automatic altitude control system, and a Secondary Surveillance Transponder (SSR) with altitude reporting.

What is the cumulative flight time limit for a pilot per year?

$1000$ hours.

What is the difference between an Alternator and a Generator?

Alternators rotate a magnetic field inside stationary coils, while generators move magnets around a coil of wire; alternators produce current at lower speeds.

What does a Transformer Rectifier Unit (TRU) do?

It converts $115V$ AC power from engine/APU/GPU sources to $28V$ DC power.

Define Critical Mach Number.

The Mach number at which a portion of the airflow around the aircraft reaches Mach $1.0$, but does not exceed it.

What is 'Mach Tuck'?

A strong nose-down pitching force caused by the center of pressure and the wing's shockwave moving aft as speed increases.

Define 'Coffin Corner'.

The high-altitude region where stall speed approaches MMO, leaving little margin between stall buffet and overspeed.

What is a disadvantage of swept wings?

They produce less lift than straight wings (poor low-speed performance) and tend to stall at the wingtip first.

What is Dutch Roll?

A sequence of out-of-phase rolling and yawing oscillations occurring when lateral stability is greater than vertical stability.

What are the standard takeoff minimums for an aircraft with 1 or 2 engines?

$1\,sm$ visibility.

What color are taxiway edge lights and taxiway centerline lights?

Taxiway edge lights are blue; centerline lights are green.

What happens to runway centerline lights in the last $3000\,ft$ of the runway?

They are alternating white/red for $2000\,ft$, then solid red for the last $1000\,ft$.

Define V1 speed.

Takeoff Decision Speed (Go/No-Go). Abort if an abnormality occurs before V1; continue if it occurs after V1.

How is hydroplaning speed calculated?

$8.6 \times \sqrt{\text{tire pressure (psi)}}$ in knots.

What is Zero Fuel Weight (ZFW)?

The maximum permissible weight of an aircraft with no disposable fuel; all weight past MZFW must be fuel in the wings.