Pneumatica

Question 1

What is pneumatic

Answer 1

Branch of mechanics that deal with mechanical properties of gas. works with pressurized gas creating mechanical motion.

Question 2

Key components of pneumatics

Answer 2

A compressor
engine of Auxiliary Power unit (APU)
External ground supply
needs a network of pipes and a on/off valve
maybe a way to reverse its direction

Question 3

How do Pneumatic get their energy

Answer 3

obtains all energy from the energy compressed air it uses

Question 4

what does a basic pnuematic system look like?

Answer 4

compressor linking to an actuator through circuit and a valve. Would work slowly which is why there is a reservoir of compressed gas that can be released to speed up operation.

Question 5

advantages of pneumatics

Answer 5

air is universally available
components are simple and lightweight
compressed air is lightweight
relatively free from temperature problems.
no fire hazard and explosion danger is minimised by careful design and operation
installation and proper fits minimizes contamination

Question 6

Types of systems - gases

Answer 6

uses compressed air and sustainable supply from atmosphere. air is moisture removed and a lil oil is used inside to help corrosion and movement of mechanical parts

Question 7

types of systems - nitrogen

Answer 7

smaller or stand alone systems can use other gasses that present asphyxiation danger

Question 8

types of systems - compressed oxygen

Answer 8

doestn have asphyxiation hazard like nitrogen but not commonly used because it can combust, more expensive and has no performance advantage.

Question 9

High pressure systems

Answer 9

gas in 2 metal bottles between 1000psi and 3000psi. cylinder has 2 valves:

• charging valve to add gas
• control valve which acts as shutoff to keep air inside till its operated

Question 10

disadvantages of high pressure

Answer 10

Cannot be refilled mid flight so it isnt used where continuous operation is. Good if there are other air pressurising units available

Question 11

Medium pressure systems

Answer 11

medium pressure at 100-150 psi, usually doesnt include air cylinder instead Bleed air after its been through cooling system.

Question 12

Low pressure systems

Answer 12

low pressure air driven gyro instruments as either the primary gyro instrument or as backup instrument when primary fails.

two types of air pump, dry and wet based on method of lubrication

Question 13

components - air compressor

Answer 13

compresses air to require pressure. converts mechanical energy of motors and engines to potential energy of compressed air. same as cycle pump, accomplished by a motor

Question 14

Air service unit

Answer 14

present in pneumatic circuit, remove dust particles, moisture and humidity from air. made up from several parts.
filter
pressure regulator
lubricator

Question 15

filter

Answer 15

Removes impurities present in air before its delivered to component

Question 16

pressure regulator

Answer 16

allows us to regulate pressure manually

Question 17

Lubricator

Answer 17

provides lube for pneumatic componets

Question 18

Pneumatic pipes

Answer 18

hollow polyurethane pipe which transport pipes from on component to another.

Question 19

Control valves

Answer 19

alter flow of air, controlled ether manually, electronically or pneumatically. 2 basic types

Direction control valves
flow control valves

Question 20

Direction control valves

Answer 20

pneumatic switching element, control pneumatic actuators

Question 21

Flow control valves

Answer 21

controls flow, more or less etc. can be used to install more than one source of air pressure

Question 22

Actuator

Answer 22

Turns potential energy stored in compressed air back into kinetic energy and movement. 2 kinds

single acting cylinder
double acting cylinder

Question 23

Single acting

Answer 23

has entry for compressed air on one side and spring on the other. air goes in spring get compressed. take away air, returns to normal

Question 24

double acting

Answer 24

one can activate the other, both ends of actuators act as inlet and outler for compressed air.

Question 25

undercarriage blow down systems

Answer 25

on all a/c with retractable landing gear. actuators enable and push the landing gear down and lock it in place. typically nitrogen or air systems., when retracted the air is returned to a tank. air from emergency system can be used to retract landing gear in case of emergency

Question 26

Pneumatics - air conditioning and ice protections

Answer 26

engines provide excess air than is needed therefore it is recycled to help with de icing the wing and cabin temp and pressurisation

Question 27

Fire extinguisher and life raft

Answer 27

Engine extinguisher can be activated using compressed gas. they are stored for these purposes. can be used to inflate life rafts and vest.

Question 28

starters

Answer 28

compressed air is used to start the engine, achieved by impingin on turbine directly, thus spinning up the engine or by spinning up a small turbine which is connected to the main engine through gearing

Question 29

shock absorbers.

Answer 29

most complex element of undercarriage, dampens all shocks of landings, taxxing and movement on uneven pavements.

2 basic types:

Uses compressibility of oil to damp out shocks
others use combination of oil and nitrogen under pressure to provide dampening

Question 30

seal inflation

Answer 30

pressurises the seal on doors and windows to aid the pressurisations, helps with irregular gap betweens doors and hatches

Question 31

idications and warning.

Answer 31

depends on what its used for. following are:

pressure tansmitters and gauges
pressure sensors and warning indicators
temp transmitters and gauges
overheat sensors and warning indicators

Question 32

Pneumatic maintenance

Answer 32

consists of:

Servicing
troubleshoot
removing and installing components
operational testing

Lube up all compressors in accordance to AMM

purge oil to remove contamintion, moisture etc.
if excessive contaminates check all the parts of the system for damage.