GoJet Systems - Powerplant

Other than providing high pressure fuel to the engine, the engine fuel pump unit also provides fuel for what two other purposes?

1. Fuel for the oil/fuel cooler 2. Pressurized fuel to start motive flow in the fuel system

What conditions must be met for thrust reverser deployment?

1. Thrust reversers must be armed 2. Weight on wheels 3. Thrust levers at idle

The compressor has how many stages?

10 stages

Normal Takeoff Thrust Rating

12,670 lbs

APR Thrust Rating

13,790 lbs

The combustor contains how many fuel injectors

18

How many ignition systems are there?

2 (Ignition A and Ignition B)

The high pressure turbine has how many stages

2 stages

The engine fuel pump unit contains how many separate fuel pumps?

3 separate fuel pumps in a single housing.

The low pressure turbine has how many stages?

4 stages

Bleed air is extracted from which compressor stages?

6th and 10th stage

Ignition A is powered by?

AC Essential Bus

During engine start, when does the starter cut out?

At 50% N2

On engine start, when should thrust be moved to idle?

At minimum of 20% N2

APR (acronym)

Automatic Performance Reserve

Ignition B is powered by?

Battery Bus. However the power for Ignition B goes from the Battery Bus through a Static Inverter. The Static Inverter converts the DC power from the Battery Bus into AC power.

Fan air is divided into:

Bypass Air and Core Air

Explain Bypass Air

Bypass air is ducted around the engine to produce approximately 80% of the engine thrust.

Explain Core Air

Core air passes through the engine. It is compressed (compressor), ignited (combustor) and exhausted (turbine & exhaust nozzle). Accounts for approximately 20% of engine thrust.

How are the inlet guide vanes, stator vanes and operability valve controlled?

Electronically controlled by the FADEC and hydraulically actuated by high pressure fuel

Explain how the Air Turbine Starter (ATS) works.

FADEC commands the starter control valve to open. This allows pressured air from the pneumatic manifold to rotate the ATS. The ATS then turns the compressor (N2).

What are the stages of the turbofan engine?

Fan, compressor, combustor, turbine and exhaust

Name the 5 different idle settings

Flight Idle Approach Idle Landing Idle Reverse Idle Ground Idle

The FADEC controls?

Fuel control, compressor airflow management and engine starting/ignition.

FADEC (acronym)

Full Authority Digital Electronic (Engine) Control

CRJ-700 Engines

GE CF34-8C5B1

The Compressor (N2) is connected to:

High Pressure Turbine

Fan Rotor (N1) connected to:

Low Pressure Turbine

How can the pilot set APR power?

Moving both thrust levers to the MAX POWER detent

When both engines are started and oil pressures are in the normal range, the oil pressure gauges on ED1 are replaced by?

N1 Fan Vib gauges

The engine fuel pump unit provides approximately how much fuel pressure to the engine?

Over 1000 PSI

What is the purpose of the operability valve?

Provides additional compressor airflow control by extracting bleed air to off load compressor pressure during engine starts and high aerodynamic loading

What is the purpose of the inlet guide vanes and stator vanes?

Provides compressor stall and surge protection

The FADEC has how many channels?

The FADEC has dual channels. One is controlling and the other is in standby. Both process and share all information.

Explain Landing Idle

The FADEC receives a weight on wheels or wheel rotation signal. This keeps the N2 RPM elevated so reverse idle can be achieved in an acceptable amount of time.

Explain the Fuel Metering Unit (FMU)

The FMU is controlled by the FADEC and distributes the fuel needed for combustion. Also supplies high pressure fuel to actuate the operability valve, stator vanes and inlet guide vanes.

What happens if both FADEC channels fail?

The engine shuts down/flames out.

What is the purpose of the exciters?

The exciter converts the AC power to a high voltage DC that is sent to the air-gap igniter.

Explain Reverse Idle

There is weight on wheels or wheel rotation, reverse thrust lever is raised, and the thrust reverser cowl is open. This setting permits the engine to achieve full reverse thrust in an acceptable amount of time.

Explain Approach Idle

Thrust lever at idle and landing gear is down or the flaps are set greater than 20. This setting permits the engine to accelerate to go-around thrust in the least amount of time.

Explain Flight Idle

Thrust lever at idle, landing gear is up and flaps are set to 20 or less. N2 RPM increases with altitude.

Explain Ground Idle

Thrust lever is set to idle and there is weight on wheels. This is the minimum thrust setting. N2 RPM varies with field altitude and ambient temperature.

What happens when an engine fails and thrust levers are in the TOGA detent?

Thrust on the operating engine is automatically increased to APR power (MAX POWER)

What happens when an engine fails and thrust levers are in the CLIMB detent?

Thrust on the operating engine is automatically increased to maximum continuous thrust (MCT)

What happens when an engine fails and thrust levers are in the cruise range?

Thrust on the operating engine is proportionally increased