8/17/2019 Final Exam Mea 322 (1)

1/89

FINAL EXAM

MEA 322 AIRCRAFT SYSTEM

8/17/2019 Final Exam Mea 322 (1)

2/89

PRINCIPLE OF

INSTRUMENTOPERATIONS

8/17/2019 Final Exam Mea 322 (1)

3/89

PRINCIPLE OF INSTRUMENT

OPERATIONS

 Aircraft instrument are required to monitor a wide variety ofaircraft conditions

Sections deals with primary operating principles of pressure

instruments, gyro instruments, electrically powered resistance

indicators, and temperature indicators

Mechanical principles are applied to instrumentation in both aprimary and supportive role

When mechanical principles are the primary operating principle,

they are often in a design unique to a specific application

Principles of operation are applied to many different types of

instruments systems in later section Principles of operation associated with mechanically operated

instruments , where the principles are uniquely applied, are

discussed individually in this chapter as the purpose, use and

operations of each mechanical instruments are reviewed

8/17/2019 Final Exam Mea 322 (1)

4/89

PROVIDE THE PRINCIPLE

OPERATION OF PRESSURE

CONTROL INSTRUMENTUsually there is one pointer, which can be adjusted

to the desired cabin altitude by the cabin altitude

set knob

In some cases there is another pointer or a rotating

scale, which also indicates the corresponding

aircraft pressure altitude

 A separate knob adjusts the existing altimeter

setting

The barometric setting selected is indicated on aseparate dial segment

The third knob adjusts the cabin rate of altitude

change

8/17/2019 Final Exam Mea 322 (1)

5/89

WHAT ARE THE PARAMETERSTHAT ARE REQUIRED FOR

HYDRAULIC SYSTEM USED?Pressure

Integrity

Flow rate

Duty cycle

Emergency or reversionary use

Heat load and dissipation

8/17/2019 Final Exam Mea 322 (1)

6/89

BLEED AIR

8/17/2019 Final Exam Mea 322 (1)

7/89

NAME AND EXPLAIN MAJOR

 AIRCRAFT AIR RELATED

SYSTEMS THAT USES BLEED AIR

 AS ITS PRIMARY SOURCE.Ice protection – the provision of hot air to provide anti

icing of engine, nacelles and the wing, tail plane or fin

leading edges; or to dislodge ice that has formed on thesurfaces

ECS and cooling – the provision of the main air source

for environmental temperature control and cooling

Pressurization – the provision of a means by which theaircraft may be pressurized, giving the crew and

passengers a more comfortable operating environment

8/17/2019 Final Exam Mea 322 (1)

8/89

HOW DOES THE AIRCRAFT HIGH

PRESSURE (HP) AIR SOURCE

PROVIDE BLEED AIR WHICH

FORMS PRIMARY SOURCE FOR AIRCRAFT RELATED SYSTEM?

 Auxiliary power unit (APU) Anti ice protection

Engine

ECS ( Environmental Control System )Pressurization

8/17/2019 Final Exam Mea 322 (1)

9/89

8/17/2019 Final Exam Mea 322 (1)

10/89

• All three of the basics gyro instruments areavailable in designs that rely on electricalpower for operation

• Normally require on of four types of powersource :

•14 Vdc

•28 Vdc

•12 Vac

•28 Vac

8/17/2019 Final Exam Mea 322 (1)

11/89

• !any of older and most of lower priced gyro instruments

are operated by a "ow of air moving over buc#ets on therotor dis#

• $low of air can be caused by drawing air through theinstrument with a venture or vacuum pump or by forcingair through the instrument from a pressure source

• Air inlet to the instruments should be %ltered to #eepcontaminants out of the instruments and out of pump

Vacuum pump & either wet pump or dry pump design

wet pump & relies on engine oil to lubricate theoperating mechanism

dry pump & relies on the proper selection of constructionmaterials to provide lubrication

8/17/2019 Final Exam Mea 322 (1)

12/89

Venturi

 generates a vacuum by moving air through a restrictedpassage & as air accelerate through the passage' sidewallpressure is reduced and air can be drawn into theventure core through a hole placed on the side of thetube at the restriction & if hole in the side venture throatis connected to a pneumatically operated gyroinstrument' air drawn through the instruments' spins thegyro and cause instrument t operate

(implest type of vacuum )pump* & normally found onaircraft not intended for instrument "ight

+rimary advantage & simple installation' no operatione,pense' reliable

-rawbac#s & requiring 1 mph of airspeed to operatethe instrument before "ight' and the possibility of theinstrument.s being closed by ice

/omes in 2 si0es designated by the amount of suctionthey can generate

8/17/2019 Final Exam Mea 322 (1)

13/89

• sed on most turbine powered airplane topower indicating and control systemneeding information about the ambient air

and aircraft speed• nput 3 pitot pressure' static pressure'

ambient air temperature

• nfo processed by a computer and signals

are sent to various systems so that theaircraft performs properly

8/17/2019 Final Exam Mea 322 (1)

14/89

 ANTI ICE CONTROL

8/17/2019 Final Exam Mea 322 (1)

15/89

PROVIDE THE PRINCIPALS OF

WING ANTI ICE CONTROL.

PROVIDE DIAGRAM TOOThe flow of hot air to the outer wingleading edges is controlled by the wing

 Anti Ice Valve.

Flow is modulated by the electricallyenabled anti icing controller – allowing air

to pass down the leading edge heating

duct

Heating duct take the form of a pipe with

holes allow flow of hot air onto the inner

surface of the leading edge.

8/17/2019 Final Exam Mea 322 (1)

16/89

 Air is bled out into the leading edge slat section

to heat the structure before being dumped

overboard

8/17/2019 Final Exam Mea 322 (1)

17/89

 ANTI SKID SYSTEM AND

DIAGRAM

8/17/2019 Final Exam Mea 322 (1)

18/89

SPECIFY THE BASIC

FUNCTIONS PERFORMED BY ANTI-SKID SYSTEM.

Touch-down protection, which prevents

landing with the brakes on

Skid control, which ensures maximumbraking efficiency

Locked-wheel protection, prevents a

wheel speed decreasing to zero becauseof runway condition

8/17/2019 Final Exam Mea 322 (1)

19/89

8/17/2019 Final Exam Mea 322 (1)

20/89

The electronic control box contains individual wheel deceleration rate skid

detection circuits with cross references between wheels and changeover

circuits to couple the control valve across the aircraft should the loss of a

wheel speed signal occur.

If a skid develops the system disconnects braking momentarily and the

adaptive pressure coordination valve ensures that brake pressure is re-applied

at low pressure after the skid than the level which allowed skid to occur

 A progressive increase in brake pressure between skids attempt to maintain ahigh level of pressure and braking efficiency

The adaptive pressure control valve dumps hydraulic pressure from the brake

when its first stage solenoid valve is energized by the commencement of a skid

signal

On wheel speed recovery, the solenoid is de-energized and the brake pressure

re-applied at a reduced pressure level, depending on the time interval of the

skid

Brake pressure then rises at a controlled rate in search of the maximum

braking level, until the next incipient skid signal occurs

8/17/2019 Final Exam Mea 322 (1)

21/89

LANDING GEAR

SYSTEM

RAYTHEON / BAE1000DIAGRAM

8/17/2019 Final Exam Mea 322 (1)

22/89

8/17/2019 Final Exam Mea 322 (1)

23/89

8/17/2019 Final Exam Mea 322 (1)

24/89

 ANTI SKID SYSTEM AND DIAGRAM

BRIEFLYDESCRIBETHE

8/17/2019 Final Exam Mea 322 (1)

25/89

BRIEFLY DESCRIBE THE

OPERATION OF AN ANTISKID

SYSTEM

Consist of an electronic control box, wheel-speed-sensor transducers, dual servo valves, failureindicating lights, and system arming switch

It has a locked-wheel protection feature whichprevents braking action prior to wheel rotation.

The system is controlled by a 2-position, 3-pole switchthat will arm or deactivate the system and reset theindicating lights.

When the system is deactivate, the wheel-brakesystem is controlled directly through the brake control

valves by means of brake pedals. When the antiskid system is armed, the brakes arecontrolled by the dual-servo valves, which meter thehydraulic fluid pressure supplied by the brake controlvalves through the pilots application of brake pedals

8/17/2019 Final Exam Mea 322 (1)

26/89

WHY IT IS NOT POSSIBLE TO LAND AN

 AIRPLANE WITH WHEELS LOCKED IF

 ANTISKID SYSTEM IS ARMED?

 Antiskid system armed – wheel brakes will be

release – no hydraulic pressure will be allowed

beyond the dual servo valves with the brake

pedal depressed

The system would automatically and rapidly

apply brake pressure compatible with airplane

and runway conditions

It may or may not result in blown tires, and also

wheel fires, and also uncommanded departure ofthe runway (skidding on the runway ) , if the

airplane is able to land with locked wheels

8/17/2019 Final Exam Mea 322 (1)

27/89

8/17/2019 Final Exam Mea 322 (1)

28/89

• +rovide the pressure necessary to operatedsuch instruments as the altimeter' airspeedindicator' and vertical3speed indicator

$N/56N 3 the tas# that a particularrole7system is assigned to accomplished

++6(9 & the )hy* behind every function

8/17/2019 Final Exam Mea 322 (1)

29/89

• t is a combined system that utili0esthe static air pressure' and thedynamic pressure due to the motion

of the aircraft through the air

8/17/2019 Final Exam Mea 322 (1)

30/89

• emoved through ba;es in pitothead and drains in the pressureline are used to remove thewater

8/17/2019 Final Exam Mea 322 (1)

31/89

•

Altimeter slows to respond•V( response degraded

•Airspeed indicator show inaccurate

indication following altitude change

8/17/2019 Final Exam Mea 322 (1)

32/89

• 5his probe also incorporate static vents "ushmounted

• 5he static vents are mounted so that they arenot a

8/17/2019 Final Exam Mea 322 (1)

33/89

8/17/2019 Final Exam Mea 322 (1)

34/89

8/17/2019 Final Exam Mea 322 (1)

35/89

8/17/2019 Final Exam Mea 322 (1)

36/89

8/17/2019 Final Exam Mea 322 (1)

37/89

• t consist of a heater mu< around theengine e,haust stac#s' an air scoop todraw ram air into heater mu

8/17/2019 Final Exam Mea 322 (1)

38/89

•  5his type of heater burns airplane fuel in a combustion chamber or tube to develop the required

heat

• Air "owing around the tube is heated and carried through ducting to the cabin

• $uel is routed from fuel cross3feed line through a %lter and a solenoid supply valve to the

diaphragm3type heater fuel pump

•  5he heater fuel pump and all e,ternal %ttings on the heater are enclosed in metal housing that

are vented and drained as a precaution against %re in the event of lea#y %ttings

• $uel passes from the heater fuel pump through a solenoid valve to the combustion chamber

spray no00le

• hen cabin heater switch is placed in =9A5 position' current is supplied to the combustion air3blower and to the ventilating fan

• $an actuate cam operated brea#er point which start the spar# plug %ring

• As combustion air3blower air increase' the vane type valve at the inlet of the combustion

chamber opens & this actuates a micro3switch which in turn operate the solenoid valve thus

allowing fuel to spray into the heater' where the spar# plug ignites the fuel

• hen the heated air "owing from the heater to the cabin e,ceeds the temperature for which the

thermostat is set' the thermostat closes the solenoid valve and stops fuel "ow to the heater

•  5he heater thermostat cools and the solenoid valve opens again to allow fuel to "ow to the

heater

• =eated air "ows from the heater' and the thermostat again causes the solenoid valve to close

• /ycling on and o< continues and heater thereby maintains an even temperature in cabin

8/17/2019 Final Exam Mea 322 (1)

39/89

• gasoline

8/17/2019 Final Exam Mea 322 (1)

40/89

• -ryer is essential in a vapor cyclesystem in such a way that theyabsorb moisture >ater? from thehumidity in the air that may havegotten inside the system duringmanufacture' assembly or evenduring service

8/17/2019 Final Exam Mea 322 (1)

41/89

• @inetic cooling & occurs when the aircraft s#in heatsup due to friction between itself and air molecules

• (olar heating & a

8/17/2019 Final Exam Mea 322 (1)

42/89

•9ngine oil

•=ydraulic oil

•earbo, oil

8/17/2019 Final Exam Mea 322 (1)

43/89

8/17/2019 Final Exam Mea 322 (1)

44/89

• $uel cooling systems have limited

applications due to the fact that fuel"ow is variable and is greatly reducedwhen the engines are throttled bac#

8/17/2019 Final Exam Mea 322 (1)

45/89

• t is an individual air3distributionsystem that routes only the coldair from the air conditioning pac#sto individually regulated outlets inthe control and passenger cabins

• ts air source is cold air

8/17/2019 Final Exam Mea 322 (1)

46/89

• t is an indication that there is waterin the system where it has fro0en atthe e,pansion valve and then

stopped the "ow of refrigerant

8/17/2019 Final Exam Mea 322 (1)

47/89

• 5he process of reducing thetemperature of a liquid below thetemperature at which it wascondensed' the pressure beingheld constant

8/17/2019 Final Exam Mea 322 (1)

48/89

8/17/2019 Final Exam Mea 322 (1)

49/89

• /abin pressuri0ation is achieved by a cabin pressure controlvalve which is installed in the cabin wall to control cabinpressure to the required value depending on the aircraftaltitude by regulating the "ow of air from the cabin

• $or aircraft where o,ygen is not used routinely and wherethe crew and passengers are free to move around as in along range passenger airliner' the cabin will be pressuri0edso that a cabin altitude of about 8 ft is never e,ceeded

• $or aircraft with the crew in %,ed positions' using o,ygenroutinely as in a military aircraft' the pressuri0ation systemis usually designed so that the cabin altitude does note,ceed about 2 ftC

8/17/2019 Final Exam Mea 322 (1)

50/89

8/17/2019 Final Exam Mea 322 (1)

51/89

• 5he altitude3limit components of the

positive pressure3relief valvesystem7the out"ow valve

8/17/2019 Final Exam Mea 322 (1)

52/89

• At 1 ft or D48 m

8/17/2019 Final Exam Mea 322 (1)

53/89

8/17/2019 Final Exam Mea 322 (1)

54/89

• 5o provide the engine with fuel >in aform suitable for combustion?

• 5o control the "ow to the requiredquantity necessary for easy starting'acceleration and stable running

• 

8/17/2019 Final Exam Mea 322 (1)

55/89

•(tores fuel

•-eliver the proper amount of clean

fuel at right pressure to meet thedemands of the engine 7 deliver auniform "ow of clean fuel under

constant pressure to meet all enginedemands

8/17/2019 Final Exam Mea 322 (1)

56/89

• $uel systems must be

constructed and arranged toensure a "ow of fuel at a rate andpressure established for proper

engine and au,iliary power3unitfunction under each li#elyoperating conditionC

8/17/2019 Final Exam Mea 322 (1)

57/89

• !ust be designed and arranged toprevent the ignition of fuel vapor

within the system by direct or sweptlightning stri#es to area where theseare li#ely to occur

• -esign must be such that fuel vaporcannot be ignited at fuel vent outlets

8/17/2019 Final Exam Mea 322 (1)

58/89

• A tan# that is a basic structure of the aircraft

• /ommonly located in the wing of fuselage' but may belocated in other location such as the hori0ontal stabili0er

•  5an#s cannot be removed because they are an integraland permanent part of the aircraft structure

• $ormed by using structural members of the wing to forma fuel3tight tan#

• Normally constructed of the same material as thesurrounding aircraft structure and sealed with a fuelproof sealing compound

8/17/2019 Final Exam Mea 322 (1)

59/89

8/17/2019 Final Exam Mea 322 (1)

60/89

•$uel "ow from the tan#s throughseparate fuel lines to the fuel

selector valve•After leaving the selector valve' thefuel "ow through the fuel strainer

and into the electric fuel pump• 5he fuel boost pump supplied fuelfor starting the engine

8/17/2019 Final Exam Mea 322 (1)

61/89

• t is held in place by several)buttons* or )snap* which attach the

bladder to the top' bottom and sidesof the compartmentC

8/17/2019 Final Exam Mea 322 (1)

62/89

• 5hey must withstand and internal

test pressure of DCG psi H 24C1D #+a Iwithout failure or lea#age and at least12GJ of pressure developed in thetan# from any ram air e

8/17/2019 Final Exam Mea 322 (1)

63/89

• t is installed in a compartment designed to hold the

tan#• 5an# must be fuel3tight but the compartment inwhich it %ts is not fuel3tight

• 5he tan# is made of aluminum component welded

together• /ompartment in which tan# is installed is structurallycomplete and does not rely on the fuel tan# forstructural integrity

• 5an#s are normally held in the compartment by

several padded straps• $ound in more ine,pensive light aircraft and on manyreciprocating3engine powered transports

8/17/2019 Final Exam Mea 322 (1)

64/89

•ipe the insides of the bladder

carefully with an oily rag leaving a%lm of engine oil on its insidesurface

•

 

8/17/2019 Final Exam Mea 322 (1)

65/89

• $or transport3type aircraft & at leastC1 percent of the total tan#capacity or 171K gallon > C24 F ? L

whichever is greaterC

• 6ther types of aircraft & C2G percent

of the tan# capacity or 171K gallon> C24 F ? L whichever is greaterC

8/17/2019 Final Exam Mea 322 (1)

66/89

• 5an# geometry & done by mechanical pro%ling toaccount for tan# shape and provide linear output

• Attitude envelope & most signi%cant factor & high

accuracy may be desirable for refueling when onthe ground

• +ermittivity variations & may adversely a

8/17/2019 Final Exam Mea 322 (1)

67/89

• (pace adMacent to tan# surfaces must be ventilated to avoidfume accumulation due to minor lea#age

• f tan# is in sealed compartment' ventilation may be limitedto drain holes large enough to prevent e,cessive pressureresulting from altitude changes

• 9ach fuel tan# must be vented from the top part of thee,pansion space

• 9ach vent outlet must be located and constructed to

minimi0e the possibility of its being obstructed by ice orother foreign matter and to prevent the siphoning of fuelduring normal operation

• Venting capacity must allow the rapid relief of e,cesspressure di

8/17/2019 Final Exam Mea 322 (1)

68/89

•  5he rotor holds the sliding vanes and is installed in the liner with itsa,is of rotation eccentric to the a,is of the liner

• hen rotor is turning' the vanes maintain a constant with thesurface of the liner

• $uel enters the inlet port and is forced by sliding vanes through the

outlet port

•  5he "oating pin aligns the sliding vanes against the surface of theliner

•

n one position the two lower vanes e,tend from the rotor' whereasthe two upper vanes are forced into the rotor by the surface of thesurface

8/17/2019 Final Exam Mea 322 (1)

69/89

• t provides a signal to the coc#pitnotifying the pilot or crew member

that is a particular %lter is bypassingfuel or is nearing a condition where itwill bypass fuel

8/17/2019 Final Exam Mea 322 (1)

70/89

• t uses pump to move fuel the fuel tan# to the engine fuel3controlcomponent

• Arrangement is required because the fuel tan#s are located too low forsuBcient head pressure to be generated or because the tan#s are somedistance fro the engine

• $uel "ows from the tan#s through separate fuel lines to the fuel3selectorvalve

• After leaving the selector valve' the fuel "ows through the fuel strainerand into the electric fuel pump

• 9ngine driven fuel pump is in parallel with the electric pump without theneed for a bypass valve

•  5he fuel boost pump supplies fuel for starting the engine' and theengine3driven pump supplies the fuel pressure necessary for normaloperationC

8/17/2019 Final Exam Mea 322 (1)

71/89

• 5hey are needed to prevent fuel%lters from being clogged by iceparticles that were trying to pass

through the fuel line

8/17/2019 Final Exam Mea 322 (1)

72/89

• $uel Mettison system is required for transport categoryand general aviation aircraft if the ma,imum ta#eo<weight e,ceeds the ma,imum landing weight

• A fuel Mettison system must be able to Mettison a large

proportion of the fuel in order to reduce weight rapidlyin order to get the acceptable landing weight & mostaircraft are not stressed to land with full fuel load

• 5his fuel Mettisoning system is usually divided into twoseparate independent systems' one for each wing' so

that lateral stability can be maintained by Mettisoningfuel from the )heavy* wing if it is necessary to do so

8/17/2019 Final Exam Mea 322 (1)

73/89

• 5o dump fuel overboard during an in3"ight emergency due to reduce theweight of the airplane to allowable

landing weight

• 5o dump all the fuel e,cept the

reverse quantity required for landing

8/17/2019 Final Exam Mea 322 (1)

74/89

• 6il "ow freely to all bearing

surfaces and the engine will beable to turn on easily

8/17/2019 Final Exam Mea 322 (1)

75/89

• Antistatic agent

• Antio,idants

•

/orrosion inhibitors• $uel system icing inhibitors

• iocides

• !etal deactivator

8/17/2019 Final Exam Mea 322 (1)

76/89

8/17/2019 Final Exam Mea 322 (1)

77/89

• ravity feed fuel system

iC =igh wing aircraft with a fuel tan# in each wing are common

iiC ith the tan#s above the engine' gravity is used to deliver the fuel

iiiC 5he space above the liquid fuel is vented to maintain atmospheric pressure onthe fuel as tan# empties

ivC 5he two tan#s are also vented to each other to ensure equal pressure whenboth tan#s feed the engine

vC A single screened outlet on each tan# feed lines that connect to either fuel

shuto< valve or multi3position selector valve

viC 5he shuto< valve has two positions : fuel 6N and fuel 6$$

viiCf installed' the selector valve provide four options : fuel shuto< to the engine Lfuel feed from the right wing tan# only L fuel feed from the left fuel tan# only Lfuel feed to the engine from both tan#s simultaneously

viiiC-ownstream of the shuto< valve or selector valve' the fuel passes through a

main system strainer & this often has a drain function to remove sediment andwater

i,C$rom there' it "ows to the carburetor or to the primer pump for engine starting

,C =aving no fuel pump' the gravity feed system is the simplest aircraft fuelsystem

+ f d f l t

8/17/2019 Final Exam Mea 322 (1)

78/89

• +ump feed fuel system

iC Fow and mid3wing single reciprocating engine aircraft cannot utili0e gravity3feedfuel systems because the fuel tan#s are not located above the engine

iiC nstead' one or more pumps are used to move the fuel from tan#s to the engineiiiC9ach tan# has a line from the screened outlet a selector valve

ivC=owever' fuel cannot be drawn from both tan#s simultaneously L if fuel is

depleted in one tan#' the pump would draw air from that tan# instead of fuelfrom the fuel tan#

vC (ince fuel is not drawn from both tan#s at the same time' there is no need to

connect the tan# vent spaces togetherviC$rom the selector valve > F9$5' =5 or 6$$ ?' fuel "ows through the main

strainer where it can supply the engine primer

viiC 5hen it "ows downstream to the fuel pumps

viiiC 5ypically' one electric and one engine3driven fuel pump are arranged in parallel

i,C 5hey draw the fuel from the fuel tan# and deliver it to the carburetor

,C 5he two pumps provide redundancy,iC 5he engine3driven fuel pumps acts as the primary pump

,iiC 5he electric pump can supply fuel should the other fail

,iiiC 5he electric pump also supplies fuel pressure while starting and is used to

prevent vapor loc# during "ight at high altitude

8/17/2019 Final Exam Mea 322 (1)

79/89

• $uel cross feed system is "e,ible when used inmultiengine airplane

• (hould an engine fail' its fuel is immediately availableto supply the demand of the other engine

• f the fuel tan# becomes damaged and loses fuel' thecorresponding engine can be supplied with fuel fromother tan#s through the cross3feed manifold

• 5his system also allow aircraft to transfer fuel from

any tan# to any other tan# for the purpose ofbalancing the weight distribution and to maintain anacceptable position for the airplane.s center of gravity

8/17/2019 Final Exam Mea 322 (1)

80/89

8/17/2019 Final Exam Mea 322 (1)

81/89

• -rawbac#s7disadvantage & if theenvironment air supply from the engine

stops then so does the supply of o,ygen

• /ompensation & small bac#up of o,ygen

systems are required for emergencysituations to enable pilot to descend toaltitudes where o,ygen levels are highenough for breathing

8/17/2019 Final Exam Mea 322 (1)

82/89

8/17/2019 Final Exam Mea 322 (1)

83/89

CONTROL SUFRACES

COMERCIAL AND

MILLITARY AIRCRAFT

8/17/2019 Final Exam Mea 322 (1)

84/89

8/17/2019 Final Exam Mea 322 (1)

85/89

8/17/2019 Final Exam Mea 322 (1)

86/89

8/17/2019 Final Exam Mea 322 (1)

87/89

 AUTOMATIC BRAKING

8/17/2019 Final Exam Mea 322 (1)

88/89

EXPLAIN THE AUTOMATIC BRAKECONTROL MECHANISM AND THE

PRE-REQUISITE THAT MUST BE

SATISFIED BEFORE AUTOBRAKING IS INITIATED?

During automatic braking a two-position

three-way solenoid valve is energized followingwheel spin-up to feed system pressure. This is

done through shuttle valves directly to the

anti-skid valves where it is modulated and

passed to the brakes. Signals from the auto

braking circuit are responsible for modulation

of pressure at the brake to match preselected

deceleration

8/17/2019 Final Exam Mea 322 (1)

89/89

Pre-requisites that must be satisfied

before auto-braking is initiated Auto-brake switch must be ON and

required deceleration selected

 Anti-skid switch must be ON and

operativeThrottle must be correctly positioned

Hydraulic pressure must be available

Brake pedals must not be depressedWheel must be spun up