Engines

Question 1

-20BR Engines

Answer 1

3500lbs thrust up to 104*F, higher ITT limits than AR

Question 2

Low Pressure (N1)

Answer 2

4 stage axial compressor/ 3 stage axial turbine

Question 3

High Pressure (N2)

Answer 3

Single stage centrifugal compressor/ Single stage axial turbine
Drives accessory gear box

Question 4

Temperature and Pressure Sensor

Answer 4

Electrically heated/ Controlled by NAC heat switch

Question 5

Bypass ratio

Answer 5

3.1 : 1

Question 6

Surge bleed valve

Answer 6

prevents compressor stalls for the LP, automatically controlled by DEEC

In MAN mode goes to 1/3 open

Question 7

Igniters per engine

Answer 7

2 
Ignition - EICAS
Green - Both on and operating
White - On but only one operating
Amber - On and neither operating

Question 8

DEEC

Answer 8

Digital Electronic Engine Control
Mounted on top of fan shroud

Provides:
Thrust management
Rating display (N1 bugs)
Engine overspeed protection
Automatic start sequence
Spool speed and temperature limiting
Surge free acceleration/deceleration
engine synchronization
APR

Gets TLA from RVDT

Question 9

Forward Accessory Section

Answer 9

Contains:
DC Starter/Generator
AC Alternator
Hydraulic Pump
Motive flow fuel pump

Question 10

Rear Accessory Section

Answer 10

Oil Pump
Fuel Pump
Fuel Control Unit

Question 11

Secondary TLA input

Answer 11

provided by control cable connecting each thrust lever to the hydromechanical fuel control unit

Question 12

Engine Idle Speeds

Answer 12

Based on squat switches and TLA
Flight Idle:65%N2
Ground Idle: 52%N2 - 20 secs after touchdown

Question 13

Overspeed protection

Answer 13

Only provide with ENG CMPTR in ON/MAN

Mechanical flyweight in the fuel control unit provides overspeed protection through the metering valve to restrict fuel flow to maint