APU

Question 1

Fuel rate

Answer 1

150 lbs/hr

Question 2

Oil system

Answer 2

self contained

Question 3

APU uses

Answer 3

Start
Emergency procedures
Single engine training
Practice autos
Powering the ECS during extreme temps

Question 4

Compressor/turbine Warning

Answer 4

No wheel containment so apu failure may result in injury to ground personnel or damage to flight critical components

Question 5

APU accessories

Answer 5

Prime/boost pump
Hydraulic accumulator with hand pump
hydraulic starter
AC generator

Question 6

Prime/boost pump functions

Answer 6

prime engine or apu fuel line

Provide fuel under pressure to apu during start and operations above 8000ft

Question 7

Accumulator functions

Answer 7

Provides hydraulic pressure for driving the apu starter and turns the compressor
Minimum 2650 psi for start
charged by backup pump with ac power or hand pump

Question 8

APU CONTR switch ON

Answer 8

Opens the apu airframe fuel shutoff valve and sends start signal to the apu electronic sequence unit or digital ESU

Question 9

2 types

Answer 9

Turbomach or garrett

Question 10

How to keep BIT codes after failure

Answer 10

DC power and APU CONTR switch left ON

Question 11

APU FAIL causes

Answer 11

high/low Ng
high/low TGT
low oil pressure
start sequence failure

Question 12

APU OIL TEMP HI

Answer 12

maximum oil temp for continuous operation

Question 13

DESU in turbomach added capability

Answer 13

controls APU overtemps by regulating the main fuel valve and start bypass valve.

Question 14

No ACCUM LOW light and no start

Answer 14

Start may be attempted by simultaneously moving the APU CONTR switch to ON and actuating the manual START/OVERRIDE lever on accumulator manifold. Which dumps pressure to starter.