CRJ 200 Engine Sample Questions

• How are the N1 and N2 sections connected?

  The N1 and N2 sections are independent.

• Explain the two paths that air can take through the engine.

  Bypass air: This air is accelerated by the N1 fan and sent around the engine nacelle. Core air: This air is accelerated by the N1 fan and then sent to the N2 section where it is compressed, fuel is added and then ignited. This burned, accelerated gas then drives the N2 and N1 turbine.

• The bypass N1 airflow on takeoff produces how much of the thrust?

  80%

• Do the thrust reversers direct the core or bypass airflow forward to assist in braking?

  The bypass airflow is diverted forward.

• What improves the efficiency of the N2 compressor and protects against stall and surge damage?

  A Variable Geometry Compressor (VG). The VG changes the angle of attack of the inlet guide vanes and the first five stages of the stator vanes. The changing of the angle of attack optimizes the airflow for best efficiency. The Fuel Control Unit (FCU) uses fuel to hydraulically change the angle of the vanes.

• Where is the ITT measured?

  Between the high and low-pressure turbine.

• What equipment does the accessory gearbox drive?

  Alternator, which powers the N1 control amplifier. Lubrication pumps for the engine. Hydraulic pump. Fuel control unit and engine fuel pump. Integral drive generator (IDG).

• What are the different jobs of the fuel system?

  Provide motive flow to the main ejector pumps and scavenge pumps. Lubricate and actuate servos in the FCU. Cool engine oil. Adjust the variable geometry compressor linkage.

• What are the different ways to stop fuel flow to the engine?

  Shut off the thrust lever. Press the fire switch light on the glare shield panel.

• What is the purpose of the fuel oil heat exchanger?

  The exchanger warms the fuel and cools the engine oil.

• Are any of the fuel filters displayed on the fuel synoptic page?

  Yes, one for each engine.

• How would you know the fuel temperature at the fuel filter?

  The temperature is displayed next to the fuel filter on the fuel synoptic page.

• What occurs when a fuel filter is clogged?

  The fuel will bypass the filter. There will be an EICAS caution message along with an amber fuel filter on the fuel synoptic page.