aeroplane structures

Question 1

an aircraft is designed to have sufficient strength to carry the _________ loading anticipated during normal flying. thus, the _____ load condition is the maximum of loads anticipated during normal operation of the aircraft. various types of aircraft will have different limit load factors. for example, a transport aircraft will have a positive limit load factor of .. negative load limit factors are usually ____ than positive load limit factors

the aircraft structure must be able to withstand this load with no ill effects, i.e. must not experience __________ deformation when subjected to the limit load. if fact, the components must withstand this load with a positive margin, and must be able to withstand a load which is at least . times the design limit load. i.e. a factor of safety. this is known as the _________ load

in the example shown, the positive limit load factor is 3.8 and the positive ultimate limit load factor is . (3.8 x 1.5)

Answer 1

an aircraft is designed to have sufficient strength to carry the MAXIMUM loading anticipated during normal flying. thus, the LIMIT load condition is the maximum of loads anticipated during normal operation of the aircraft. various types of aircraft will have different limit load factors. for example, a transport aircraft will have a positive limit load factor of 3.8. negative load limit factors are usually LESS than positive load limit factors

the aircraft structure must be able to withstand this load with no ill effects, i.e. must not experience PERMANENT deformation when subjected to the limit load. if fact, the components must withstand this load with a positive margin, and must be able to withstand a load which is at least 1.5 times the design limit load. i.e. a factor of safety. this is known as the ULTIMATE load

in the example shown, the positive limit load factor is 3.8 and the positive ultimate limit load factor is 5.7 (3.8 x 1.5)

Question 2

STRENGTH REQUIREMENTS

ultimate loads are dealt with in one of two ways:

• the structure must be able to support ultimate loads without failure for at least _ seconds, or…
• proof of strength can be shown by dynamic tests simulating ______ load conditions (CS25.30_)

Answer 2

STRENGTH REQUIREMENTS

ultimate loads are dealt with in one of two ways:

• the structure must be able to support ultimate loads without failure for at least 3 seconds, or…
• proof of strength can be shown by dynamic tests simulating ACTUAL load conditions (CS25.305)

Question 3

PROOF OF STRUCTURE

this is achieved by carrying out a combination of ______ and ________ tests, or by using structural analysis based on experience of ________ structures. (CS25.30_)

Answer 3

PROOF OF STRUCTURE

this is achieved by carrying out a combination of STATIC and DYNAMIC tests, or by using structural analysis based on experience of SIMLAR structures. (CS25.307)

Question 4

HOOP STRESS

in a pressurised aircraft, the fuselage is subjected to a stress that is caused by the ________ in pressure between the inside and outside of the pressurised cabin. this stress is known as hoop stress.

the longitudinal stress is always ____ than the hoop stress

Answer 4

HOOP STRESS

in a pressurised aircraft, the fuselage is subjected to a stress that is caused by the DIFFERENCE in pressure between the inside and outside of the pressurised cabin. this stress is known as hoop stress.

the longitudinal stress is always LESS than the hoop stress

Question 5

FATIGUE TESTING

fatigue testing is carried out on an aircraft structure taken from the __________ line

Answer 5

FATIGUE TESTING

fatigue testing is carried out on an aircraft structure taken from the PRODUCTION line

Question 6

SAFE LIFE

… is the period during which it is considered that _______ of a component is extremely unlikely

Answer 6

SAFE LIFE

… is the period during which it is considered that FAILURE of a component is extremely unlikely

Question 7

FAIL SAFE STRUCTURE

a fail safe structure can be described as a structure having ________ load paths. that means that the loads are shared by an adjacent member. if one part fails, the load it carried will now be carried by the adjacent member for a ________ period, at least until the next periodic _________

the fail safe concept is not restricted to __________ components for example, consider the passenger cabin ________. these windows must be able to take the full cabin pressurisation loads imposed on them during flight.

it must be remembered that once an initial failure has taken place, the ___________ in the structure is no longer present and an inspection __________ capable of finding the failure before it progresses too far is essential

Answer 7

FAIL SAFE STRUCTURE

a fail safe structure can be described as a structure having MULTIPLE load paths. that means that the loads are shared by an adjacent member. if one part fails, the load it carried will now be carried by the adjacent member for a LIMITED period, at least until the next periodic INSPECTION

the fail safe concept is not restricted to STRUCTURAL components for example, consider the passenger cabin WINDOWS. these windows must be able to take the full cabin pressurisation loads imposed on them during flight.

it must be remembered that once an initial failure has taken place, the REDUNDANCY in the structure is no longer present and an inspection PROGRAMME capable of finding the failure before it progresses too far is essential

Question 8

DAMAGE TOLERANCE

damage tolerance is the attribute of a structure that permits it to retain its required ________ strength for a period of use after the structure has sustained a given level of fatigue, corrosion, or damage

this concept requires the cracks to be found by _______ inspections and relies on a slow ___________ rate for the cracks. the inspection cycle must be _________ and amended to support this concept

the inspection cycle is determined on the basis that if a crack of detectable length has been ______ during an inspection, the structure will allow this crack to ________ in length until the next inspection before it becomes ___ dangerous. the minimum detectable length of a crack is agreed by the ____________ and the ___________ authority when the aircraft is being prepared for the issue of its certificate of airworthiness

Answer 8

DAMAGE TOLERANCE

damage tolerance is the attribute of a structure that permits it to retain its required RESIDUAL strength for a period of use after the structure has sustained a given level of fatigue, corrosion, or damage

this concept requires the cracks to be found by ROUTINE inspections and relies on a slow PROPAGATION rate for the cracks. the inspection cycle must be DESIGNED and amended to support this concept

the inspection cycle is determined on the basis that if a crack of detectable length has been MISSED during an inspection, the structure will allow this crack to INCREASE in length until the next inspection before it becomes TOO dangerous. the minimum detectable length of a crack is agreed by the MANUFACTURERS and the CERTIFICATION authority when the aircraft is being prepared for the issue of its certificate of airworthiness

Question 9

STRESS RAISERS

at fuselage cut outs such as windows and doorways additional ____________ frames and ________ are used to absorb the stress normally carried by the skin and stringers and transferred from the door by its hinges and stops

however, because the doubler is ________ than the original skin it can transfer loads at its edges _______ than the skin was designed to take. to prevent this, doublers are usually ________ or chamfered across the area of the attachment fasteners so that the stress is progressively ___________ into the existing skin

Answer 9

STRESS RAISERS

at fuselage cut outs such as windows and doorways additional STRENGTHENING frames and DOUBLERS are used to absorb the stress normally carried by the skin and stringers and transferred from the door by its hinges and stops

however, because the doubler is STRONGER than the original skin it can transfer loads at its edges GREATER than the skin was designed to take. to prevent this, doublers are usually TAPERED or chamfered across the area of the attachment fasteners so that the stress is progressively DISSIPATED into the existing skin

Question 10

STRUCTURAL CLASSIFICATION

for the purpose of assessing ________, and the type of ______ to be carried out, the aircraft structure is divided into two categories:

• _______ structure
• _________ structure

diagrams are prepared by each manufacturer to denote how the various structures fall into these categories. on the diagrams, _______ is used to denote the categories

some manufacturers use a colour code to denote the categories:

• ___ - denoted primary structure
• ______ - denoted secondary structure
• _____ - denoted tertiary structure (no longer in general use)

some aircraft may have parts of the structure designated as ________. this includes _______ stressed parts such as fairings, wheel shields and minor component brackets. this term is falling from general use

Answer 10

STRUCTURAL CLASSIFICATION

for the purpose of assessing DAMAGE, and the type of REPAIR to be carried out, the aircraft structure is divided into two categories:

• PRIMARY structure
• SECONDARY structure

diagrams are prepared by each manufacturer to denote how the various structures fall into these categories. on the diagrams, SHADING is used to denote the categories

some manufacturers use a colour code to denote the categories:

• RED - denoted primary structure
• YELLOW - denoted secondary structure
• GREEN - denoted tertiary structure (no longer in general use)

some aircraft may have parts of the structure designated as TERTIARY. this includes LIGHTLY stressed parts such as fairings, wheel shields and minor component brackets. this term is falling from general use

Question 11

PRINCIPAL STRUCTURAL ELEMENTS

certain parts of primary structure are defined as principal structural elements (PSE’s). these are components which contribute significantly to carrying flight, ground and pressurisation loads and whose failure could result is ___________ failure of the aeroplane

Answer 11

PRINCIPAL STRUCTURAL ELEMENTS

certain parts of primary structure are defined as principal structural elements (PSE’s). these are components which contribute significantly to carrying flight, ground and pressurisation loads and whose failure could result is CATASTROPHIC failure of the aeroplane

Question 12

ZONING OF AIRCRAFT STRUCTURE

a zone is identified by one of three indicators, depending on whether it is a _____ zone, major ___-zone or simply a ____.

• major zone - e.g. 100 - 900
• major sub zone - e.g. 310, 320, etc…
• zone - e.g. 321, 322, 323 etc…

Answer 12

ZONING OF AIRCRAFT STRUCTURE

a zone is identified by one of three indicators, depending on whether it is a MAJOR zone, major SUB-zone or simply a ZONE.

• major zone - e.g. 100 - 900
• major sub zone - e.g. 310, 320, etc…
• zone - e.g. 321, 322, 323 etc…

Question 13

STATION IDENTIFICATION SYSTEMS

in order to accurately locate specific positions anywhere on the aircraft, a system like the ____ numbering system for maps and _________ is used

Answer 13

STATION IDENTIFICATION SYSTEMS

in order to accurately locate specific positions anywhere on the aircraft, a system like the GRID numbering system for maps and NAVIGATION is used

Question 14

FUSELAGE STATIONS

the datum is usually at or about the ____ of the aircraft and in some cases it may be a point in space in _____ of the aircraft (measured forward from a specific position)

station number aft of the datum have _______ values and station number forward of the datum have ________ values

Answer 14

FUSELAGE STATIONS

the datum is usually at or about the NOSE of the aircraft and in some cases it may be a point in space in FRONT of the aircraft (measured forward from a specific position)

station number aft of the datum have POSITIVE values and station number forward of the datum have NEGATIVE values

Question 15

WATER LINE

water line is the vertical distance from the __________ datum. this datum may be some convenient part of the fuselage, such as passenger _____ floor, or it may be the ______ with the aircraft on its wheels. water line measurements above the datum have _______ values and those below have ________ values

Answer 15

WATER LINE

water line is the vertical distance from the LONGITUDINAL datum. this datum may be some convenient part of the fuselage, such as passenger CABIN floor, or it may be the GROUND with the aircraft on its wheels. water line measurements above the datum have POSITIVE values and those below have NEGATIVE values

Question 16

BUTT LINES OR BUTTOCK LINES

body buttock lines (BL) are measurements left or right of a vertical plane running through the aircraft __________ axis. expressed as LBL or RBL, they may be used for _________ locations, particularly in wide bodied aircraft and also wing locations on _______ aircraft

W.STA - wing station. a plane perpendicular to the wing set at __ degrees from the leading edge
WBL - wing buttock line - a plane perpendicular to the wing and _________ to the body buttock line

__________ and even large control surfaces are treated in much the same way

Answer 16

BUTT LINES OR BUTTOCK LINES

body buttock lines (BL) are measurements left or right of a vertical plane running through the aircraft LONGITUDINAL axis. expressed as LBL or RBL, they may be used for FUSELAGE locations, particularly in wide bodied aircraft and also wing locations on SMALLER aircraft

W.STA - wing station. a plane perpendicular to the wing set at 90 degrees from the leading edge
WBL - wing buttock line - a plane perpendicular to the wing and PARALLEL to the body buttock line

STABILISERS and even large control surfaces are treated in much the same way

Question 17

DRAINAGE

airframe drainage can be divided into two areas:

• ________ drains
• _______ drains

two types of external drains rely upon pressurised ___ within the cabin to keep the valves closed, one valve has a rubber ______ seal and the other a _____ loaded seal. both are ____ when the aircraft is stationary on the ground, allowing the fluids to drain overboard. during flights, the valves _____ thus preventing any air losses from the cabin areas. illustrated is the use of a _______ compound in areas which may act as a fluid trap. this compound, normally a __________ sealant, fills the cavity and brings the level up to the drain hole, thus ensuring all fluids are allowed to drain out,

also illustrated is another type of drain valve. this valve uses cabin air pressure to close off the drain path by moving the _______ down to seal the drain. when cabin pressure is removed, the spring assists the valve to open and drain out any fluid.

Answer 17

DRAINAGE

airframe drainage can be divided into two areas:

• EXTERNAL drains
• INTERNAL drains

two types of external drains rely upon pressurised AIR within the cabin to keep the valves closed, one valve has a rubber FLAPPER seal and the other a SPRING loaded seal. both are OPEN when the aircraft is stationary on the ground, allowing the fluids to drain overboard. during flights, the valves CLOSE thus preventing any air losses from the cabin areas. illustrated is the use of a LEVELLING compound in areas which may act as a fluid trap. this compound, normally a RUBBERISED sealant, fills the cavity and brings the level up to the drain hole, thus ensuring all fluids are allowed to drain out,

also illustrated is another type of drain valve. this valve uses cabin air pressure to close off the drain path by moving the PLUNGER down to seal the drain. when cabin pressure is removed, the spring assists the valve to open and drain out any fluid.

Question 18

TOILETS AND GALLEY VENTILATION

the galleys and toilets are ventilated by allowing pressurised cabin air to escape to atmosphere. the galleys are ventilated through vent _____ in the ______ panel. the toilet compartments are vented by air flowing through a ___ between the toilet ______ and the toilet bowl ______, and into the vent ____ located beneath the toilet shroud.

the ventilation system consists of the following components:
- _______ - this limits the ______ of cabin air when the aircraft is pressurised

Answer 18

TOILETS AND GALLEY VENTILATION

the galleys and toilets are ventilated by allowing pressurised cabin air to escape to atmosphere. the galleys are ventilated through vent INLETS in the CEILING panel. the toilet compartments are vented by air flowing through a GAP between the toilet SHROUD and the toilet bowl FLANGE, and into the vent DUCT located beneath the toilet shroud.

the ventilation system consists of the following components:
- VENTURI - this limits the OUTFLOW of cabin air when the aircraft is pressurised

Question 19

CABIN FLOOR VENTS

vent _____ are fitted along the side of the cabin at floor level. these are connected via holes in the aircraft structure to _____ ___ panels in the sidewalls of the cargo compartments. these blowout panels are secured by _______ mouldings around their edge. this prevents the spread of fire between compartments. the panels will blow out or in at a differential pressure of _psi. this will ________ the pressure above and below the floor, preventing _________ of the floor. distortion can cause damage to the _______ and other services passing under the floor

Answer 19

CABIN FLOOR VENTS

vent GRILLS are fitted along the side of the cabin at floor level. these are connected via holes in the aircraft structure to BLOW OUT panels in the sidewalls of the cargo compartments. these blowout panels are secured by RUBBER mouldings around their edge. this prevents the spread of fire between compartments. the panels will blow out or in at a differential pressure of 1psi. this will EQUALISE the pressure above and below the floor, preventing DISTORTION of the floor. distortion can cause damage to the CONTROLS and other services passing under the floor

Question 20

EQUIPMENT COOLING

____ are used to draw air across the equipment racks to cool the equipment. this air is then exhausted _________

Answer 20

EQUIPMENT COOLING

FANS are used to draw air across the equipment racks to cool the equipment. this air is then exhausted OVERBOARD

Question 21

LIGHTNING STRIKE PROTECTION. BONDING

if the ______ on different parts of the aircraft was not of the ____ value, the potential difference could cause sparking between the different parts. this could present a danger of some extent to both the aircraft and the occupants, due to:

• _______ to aircraft structure
• ____ hazard
• _____ interference
• ________ shocks
• corrosion - electro-_______ action

to prevent any build up of potential difference between parts of the aircraft, a very low resistance interconnection must exist between all components. this is called ‘_______’

bonding will also ________ the effect of a lightning strike on the aircraft

Answer 21

LIGHTNING STRIKE PROTECTION. BONDING

if the CHARGE on different parts of the aircraft was not of the SAME value, the potential difference could cause sparking between the different parts. this could present a danger of some extent to both the aircraft and the occupants, due to:

• DAMAGE to aircraft structure
• FIRE hazard
• RADIO interference
• ELECTRICAL shocks
• corrosion - electro-CHEMICAL action

to prevent any build up of potential difference between parts of the aircraft, a very low resistance interconnection must exist between all components. this is called ‘BONDING’

bonding will also MINIMISE the effect of a lightning strike on the aircraft

Question 22

BONDING TEST

the complete aircraft must be checked at various times for the ________ of its bonding. this is called a _______ test and should be carried out:

• when it is called for in the ___________ schedule
• after refitting of ______ components e.g. tailplanes, fin, control surfaces
• if bonding ________ or leads are replaced
• after reports of electric _____ from the structure
• after __________ or modification to electrical systems

the main discharge path of the static to ground must also be checked and this is called a ______ _________ check

Answer 22

BONDING TEST

the complete aircraft must be checked at various times for the EFFICIENCY of its bonding. this is called a BONDING test and should be carried out:

• when it is called for in the MAINTENANCE schedule
• after refitting of MAJOR components e.g. tailplanes, fin, control surfaces
• if bonding JUMPERS or leads are replaced
• after reports of electric SHOCK from the structure
• after REPLACEMENT or modification to electrical systems

the main discharge path of the static to ground must also be checked and this is called a STATIC CONDUCTIVITY check

Question 23

STRESSED SKIN FUSELAGE CONSTRUCTION

the skin takes mainly ______ loads. the framework to which it is attached taking the _________ loads

Answer 23

STRESSED SKIN FUSELAGE CONSTRUCTION

the skin takes mainly TENSION loads. the framework to which it is attached taking the COMPRESSIVE loads

Question 24

SEMI-MONOCOQUE CONSTRUCTION

there are a number of advantages in the use of the semi-monocoque fuselage. the bulkheads, frames, stringers and longerons facilitate the design and construction of a _________ fuselage and add to the strength and _______ of the structure. the main advantage however, lies in the fact that it does not depend on a ___ members for strength and rigidity. this means that a semi-monocoque fuselage, because of its stressed skin construction, may withstand considerable ________ and still be strong enough to hold together. this strength is further enhanced by fitting stiffeners/_______ at door and window positions. may also be known as ________ skin construction

Answer 24

SEMI-MONOCOQUE CONSTRUCTION

there are a number of advantages in the use of the semi-monocoque fuselage. the bulkheads, frames, stringers and longerons facilitate the design and construction of a STREAMLINED fuselage and add to the strength and RIGIDITY of the structure. the main advantage however, lies in the fact that it does not depend on a FEW members for strength and rigidity. this means that a semi-monocoque fuselage, because of its stressed skin construction, may withstand considerable DAMAGE and still be strong enough to hold together. this strength is further enhanced by fitting stiffeners/DOUBLERS at door and window positions. may also be known as STRESSED skin construction

Question 25

LONGERONS

the primary _______ loads are carried by the longerons.

it is usual for ____ rails to be mounted on the longerons

Answer 25

LONGERONS

the primary BENDING loads are carried by the longerons.

it is usual for SEAT rails to be mounted on the longerons

Question 26

STRINGERS

the stringers are also longitudinal members but ______ and ______ than longerons. where possible, stringers run the _______ length of the fuselage. they pass through cut outs in the ______ and _______

Answer 26

STRINGERS

the stringers are also longitudinal members but SMALLER and LIGHTER than longerons. where possible, stringers run the COMPLETE length of the fuselage. they pass through cut outs in the FRAMES and FORMERS

Question 27

CLEATS

cleats and clips are small __________ alloy brackets used to attach the ________ to the frames and formers

Answer 27

CLEATS

cleats and clips are small ALUMINIUM alloy brackets used to attach the STRINGERS to the frames and formers

Question 28

DOUBLERS

these are commonly _________ layers of skin, not necessarily the same _________ as the skin to which they are attached, to provide additional _______ where required, e.g. around the openings for _____, hatches and windows

Answer 28

DOUBLERS

these are commonly ADDITIONAL layers of skin, not necessarily the same THICKNESS as the skin to which they are attached, to provide additional STRENGTH where required, e.g. around the openings for DOORS, hatches and windows

Question 29

STRUTS AND TIES

_____ carry compressive loads, ____ carry tensile loads

Answer 29

STRUTS AND TIES

STRUTS carry compressive loads, TIES carry tensile loads

Question 30

BEAMS

they carry _______ loads, the most obvious example being the wing _____

Answer 30

BEAMS

they carry BENDING loads, the most obvious example being the wing SPARS

Question 31

INTERCOSTALS

intercostals are usually _______ section members _______ at each end. they are used in place of ________ and fit between, and are riveted to, adjacent frames and formers

Answer 31

INTERCOSTALS

intercostals are usually CHANNEL section members FLANGED at each end. they are used in place of STRINGERS and fit between, and are riveted to, adjacent frames and formers

Question 32

CRACK STOPPER

a reinforcing member normally placed at _____ angles to the path of an anticipated _____ which will reduce the rate of further ___________

Answer 32

CRACK STOPPER

a reinforcing member normally placed at RIGHT angles to the path of an anticipated CRACK which will reduce the rate of further PROPAGATION

Question 33

FISH PLATES

fish plates are used in ______ work or during construction to _________ the intersection between a ___ and a stringer or a ______ and a stringer

Answer 33

FISH PLATES

fish plates are used in REPAIR work or during construction to STRENGTHEN the intersection between a RIB and a stringer or a FRAME and a stringer

Question 34

COUNTERSINKING AND DIMPLING

as a general guide, sheet metal __SWG and under is dimpled, whereas sheet metal __SWG and thicker is countersunk

Answer 34

COUNTERSINKING AND DIMPLING

as a general guide, sheet metal 20SWG and under is dimpled, whereas sheet metal 18SWG and thicker is countersunk

Question 35

SURFACE PROTECTION. SEALING

freshly formed anodic films are ______ so the coating is sealed to improve ________ resistance

sealing may be carried out by immersing the part in hot _____. this avoids the _______ change caused by the dichromate solution

alternatively, the parts may be sealed by immersing in a hot solution of _________ or sodium dichromate and water. the resulting colour being ______/green on sulphuric acid films and ____ green on thick hard films

Answer 35

SURFACE PROTECTION. SEALING

freshly formed anodic films are POROUS so the coating is sealed to improve CORROSION resistance

sealing may be carried out by immersing the part in hot WATER. this avoids the COLOUR change caused by the dichromate solution

alternatively, the parts may be sealed by immersing in a hot solution of POTASSIUM or sodium dichromate and water. the resulting colour being YELLOW/green on sulphuric acid films and DARK green on thick hard films

Question 36

PRIMERS

exterior primers are applied to the exterior of the aircraft and are usually __________ with a polyurethane topcoat. there are two main types:

• _____ urethane compatible
• ____urethane primer

very often, where an _____ primer has been used, the topcoat may be stripped off leaving the primer ______. after removal of the topcoat, the primer is washed with _______ to remove any contaminants

Answer 36

PRIMERS

exterior primers are applied to the exterior of the aircraft and are usually OVERCOATED with a polyurethane topcoat. there are two main types:

• EPOXY urethane compatible
• POLYurethane primer

very often, where an EPOXY primer has been used, the topcoat may be stripped off leaving the primer INTACT. after removal of the topcoat, the primer is washed with SOLVENT to remove any contaminants

Question 37

PAINT SPRAYING

on completion of paint spraying, the equipment must be thoroughly ______. if any paint is allowed to solidify, the equipment will be ______

Answer 37

PAINT SPRAYING

on completion of paint spraying, the equipment must be thoroughly CLEANED. if any paint is allowed to solidify, the equipment will be RUINED

Question 38

SURFACE PREPARATION. CHEMICAL STRIPPING

chemical paint stripping is still the most ______ used method. approved proprietary paint strippers are available for removing particular types of paint. ______ and __________ paints are the most difficult to remove.

the ___ will specify the paint stripper to be used. it must be noted that some paint strippers may:

• affect __________ used for attaching sealing and chafing strips
• cause hydrogen ___________ of steels having tensile strength in excess of ____N/mm2 (__tons/in2)
• damage _________ materials and _______ windows

Answer 38

SURFACE PREPARATION. CHEMICAL STRIPPING

chemical paint stripping is still the most WIDELY used method. approved proprietary paint strippers are available for removing particular types of paint. EPOXY and POLYURETHANE paints are the most difficult to remove.

the SRM will specify the paint stripper to be used. it must be noted that some paint strippers may:

• affect ADHESIVES used for attaching sealing and chafing strips
• cause hydrogen EMBRITTLEMENT of steels having tensile strength in excess of 1000N/mm2 (65tons/in2)
• damage COMPOSITE materials and ACRYLIC windows

Question 39

RIGGING CHECKS

although the ________ and ________ angles of conventional modern aircraft cannot be adjusted, they should be checked at specified periods and after ______ landings or ________ flight loads to ensure that there is no _________ and that the angles are within the ________ limits. the actual figures obtained are recorded in the aircraft ___ book

the usual method of checking rigging angles is by the use of special boards made from wood or metal on which can be placed an ___________. on larger aircraft, rigging is usually checked by means of sighting rods and a __________

Answer 39

RIGGING CHECKS

although the DIHEDRAL and INCIDENCE angles of conventional modern aircraft cannot be adjusted, they should be checked at specified periods and after HEAVY landings or ABNORMAL flight loads to ensure that there is no DISTORTION and that the angles are within the PERMITTED limits. the actual figures obtained are recorded in the aircraft LOG book

the usual method of checking rigging angles is by the use of special boards made from wood or metal on which can be placed an INCLINOMETER. on larger aircraft, rigging is usually checked by means of sighting rods and a THEODOLITE

Question 40

RIGGING CHECKS. WING AND TAILPLANE DIHEDRAL

checked by using special dihedral _____ supplied by the aircraft manufacturer, or a _______ edge and an _________. the board or straight edge must be placed in the correct ________ as marked on the wing or tailplane or as stated in the __________ manual

Answer 40

RIGGING CHECKS. WING AND TAILPLANE DIHEDRAL

checked by using special dihedral BOARD supplied by the aircraft manufacturer, or a STRAIGHT edge and an INCLINOMETER. the board or straight edge must be placed in the correct POSITION as marked on the wing or tailplane or as stated in the MAINTENANCE manual

Question 41

RIGGING CHECKS. WING AND TAILPLANE INCIDENCE CHECK

usually checked at ___ positions, _______ and _______ to ensure that the wing or tailplane is not twisted, or to check, for example, ____ ___. special ________ boards, supplied by the aircraft manufacturer are placed at specified positions on the wing and tailplane. the ___________ is placed on top of the board and should read zero or within a permitted _________ about zero.

Answer 41

RIGGING CHECKS. WING AND TAILPLANE INCIDENCE CHECK

usually checked at TWO positions, INBOARD and OUTBOARD to ensure that the wing or tailplane is not twisted, or to check, for example, WASH OUT. special INCIDENCE boards, supplied by the aircraft manufacturer are placed at specified positions on the wing and tailplane. the INCLINOMETER is placed on top of the board and should read zero or within a permitted TOLERANCE about zero.

Question 42

DISTORTED FUSELAGE

the fuselage may be distorted in one of three ways:

• bow about the _______ plane
• bow about the _________ plane
• twist

Answer 42

DISTORTED FUSELAGE

the fuselage may be distorted in one of three ways:

• bow about the VERTICAL plane
• bow about the HORIZONTAL plane
• twist

Question 43

DISTORTED FUSELAGE. BOW ABOUT THE VERTICAL PLANE

check by dropping _____ lines from the _____ line of the structure at the ____ and ____, and at intermediate positions. a line stretched fore and aft, connecting the front and ______ plumb lines, should also contact the rearmost one. if this does not occur it indicates bowing and should be measured and compared with the manufacturers __________

Answer 43

DISTORTED FUSELAGE. BOW ABOUT THE VERTICAL PLANE

check by dropping PLUMB lines from the CENTRE line of the structure at the NOSE and TAIL, and at intermediate positions. a line stretched fore and aft, connecting the front and CENTRE plumb lines, should also contact the rearmost one. if this does not occur it indicates bowing and should be measured and compared with the manufacturers TOLERANCE

Question 44

DISTORTED FUSELAGE. BOW ABOUT THE HORIZONTAL PLANE.

known as _______ and _______

if the lower fuselage has become ‘concave’ due to distortion, then ________ has occurred. the incidence of a fixed tailplane might ________

sagging is the opposite situation and tailplane incidence might ________

the aircraft manual will give procedure for checking this

Answer 44

DISTORTED FUSELAGE. BOW ABOUT THE HORIZONTAL PLANE.

known as HOGGING and SAGGING

if the lower fuselage has become ‘concave’ due to distortion, then HOGGING has occurred. the incidence of a fixed tailplane might INCREASE

sagging is the opposite situation and tailplane incidence might DECREASE

the aircraft manual will give procedure for checking this

Question 45

RIGGING CHECKS WITH SIGHTING RODS

the readings thus obtained must be within the tolerances permitted by the ___________ (details of which are normally included in the rigging drawing), and entered in the aircraft ___ book for a permanent record

Answer 45

RIGGING CHECKS WITH SIGHTING RODS

the readings thus obtained must be within the tolerances permitted by the MANUFACTURER (details of which are normally included in the rigging drawing), and entered in the aircraft LOG book for a permanent record

Question 46

SYMMETRY CHECK

the actual measurements relating to the aircraft concerned are given in the aircraft ___ book

note that the aircraft must be in _______ position when using plumb bobs to check symmetry

Answer 46

SYMMETRY CHECK

the actual measurements relating to the aircraft concerned are given in the aircraft LOG book

note that the aircraft must be in RIGGING position when using plumb bobs to check symmetry

Question 47

PRESSURISED FUSELAGE CONSTRUCTION

a fuselage with a non-circular cross section will try to become circular under internal _______. this places bending loads on the fuselage frames. the ‘double ______’ shape of fuselage is an exception. the shape in this case is maintained by _______ in the floor beams. floor beams are attached to the frames and run horizontally across the fuselage. these beams support the cabin flooring.

components that are attached to the fuselage at reinforced areas include ______, landing gear, _______, stabilisers, jackpads and _________.

the structure of the aircraft vertical stabiliser may be an ________ part of the aircraft fuselage. alternatively, the vertical and horizontal stabilisers may be attached to _______ or reinforced bulkheads by _____ so that they can be easily removed for replacement or repair operations

Answer 47

PRESSURISED FUSELAGE CONSTRUCTION

a fuselage with a non-circular cross section will try to become circular under internal PRESSURE. this places bending loads on the fuselage frames. the ‘double BUBBLE’ shape of fuselage is an exception. the shape in this case is maintained by TENSION in the floor beams. floor beams are attached to the frames and run horizontally across the fuselage. these beams support the cabin flooring.

components that are attached to the fuselage at reinforced areas include WINGS, landing gear, ENGINES, stabilisers, jackpads and ANTENNAS.

the structure of the aircraft vertical stabiliser may be an INTEGRAL part of the aircraft fuselage. alternatively, the vertical and horizontal stabilisers may be attached to CASTINGS or reinforced bulkheads by BOLTS so that they can be easily removed for replacement or repair operations

Question 48

AERODYNAMIC SMOOTHNESS

exterior surface aerodynamic smoothness may be classified in three categories:

• _____ critical
• critical
• ___ critical

critical aerodynamic surfaces are those surfaces which require a ____ degree of aerodynamic smoothness

Answer 48

AERODYNAMIC SMOOTHNESS

exterior surface aerodynamic smoothness may be classified in three categories:

• EXTRA critical
• critical
• NON critical

critical aerodynamic surfaces are those surfaces which require a HIGH degree of aerodynamic smoothness

Question 49

AIRCRAFT DOOR REQUIREMENTS

an _________ must be provided in the control cabin to indicate to the crew that the passenger doors are closed and _______

Answer 49

AIRCRAFT DOOR REQUIREMENTS

an INDICATOR must be provided in the control cabin to indicate to the crew that the passenger doors are closed and LOCKED

Question 50

DOOR INDICATIONS AND WARNINGS

in the interests of safety, knowledge of the opening and closing __________ of a particular door is essential. unless operated in the _______ sequence, initiation of the door opening sequence could cause the inadvertent deployment of an emergency _______ slide and/or the operation of built in powered air stairs

Answer 50

DOOR INDICATIONS AND WARNINGS

in the interests of safety, knowledge of the opening and closing SEQUENCES of a particular door is essential. unless operated in the CORRECT sequence, initiation of the door opening sequence could cause the inadvertent deployment of an emergency ESCAPE slide and/or the operation of built in powered air stairs

Question 51

ACCESS PANELS AND HATCHES

access panels and hatches will invariably be of the inward opening ____ type design to reduce the possibility of them being lost through pressurisation loads. most will also be linked to the ‘door ______’ electrical indication system

Answer 51

ACCESS PANELS AND HATCHES

access panels and hatches will invariably be of the inward opening PLUG type design to reduce the possibility of them being lost through pressurisation loads. most will also be linked to the ‘door UNSAFE’ electrical indication system

Question 52

FLIGHT DECK WINDSCREEN CONSTRUCTION

during flight, the windscreens are heated ___________. this prevents ___ forming and makes the window more _________ and able to withstand birdstrikes

the impact strength of a laminated windscreen is based on the ability of the __________ to stretch and reform and thus ______ the shock load, assuming that the impact is great enough to shatter the glass. for this reason, windscreens are secured to the windscreen frame by _____ passed through the edges of the windscreen

windshields have a bluish green ____ and fine _______ lines may be visible. these lines, called ________ lines, are minute separations between vertical strips of _________ coating which limit coating _______ to the affected strip

___ temperature control sensors are laminated into the windshield _________ to the conductive coating. only one control sensor is used; one is a ______ that is used only if the other fails

Answer 52

FLIGHT DECK WINDSCREEN CONSTRUCTION

during flight, the windscreens are heated CONTINUOUSLY. this prevents ICE forming and makes the window more RESILIENT and able to withstand birdstrikes

the impact strength of a laminated windscreen is based on the ability of the INTERLAYER to stretch and reform and thus ABSORB the shock load, assuming that the impact is great enough to shatter the glass. for this reason, windscreens are secured to the windscreen frame by BOLTS passed through the edges of the windscreen

windshields have a bluish green TINT and fine VERTICAL lines may be visible. these lines, called ISOLATION lines, are minute separations between vertical strips of CONDUCTIVE coating which limit coating BURNOUT to the affected strip

TWO temperature control sensors are laminated into the windshield ADJACENT to the conductive coating. only one control sensor is used; one is a SPARE that is used only if the other fails

Question 53

PASSENGER CABIN WINDOWS. GENERAL

the passenger cabin windows are designed to be ____ safe and normally have ___ panes of acrylic plastic.

fail safe structure is ensured by the _____ pane which is designed for . times the differential pressure at __ celsius. if one fails, the other pane carries the load and prevents loss of cabin ________

Answer 53

PASSENGER CABIN WINDOWS. GENERAL

the passenger cabin windows are designed to be FAIL safe and normally have TWO panes of acrylic plastic.

fail safe structure is ensured by the INNER pane which is designed for 1.5 times the differential pressure at 21 celsius. if one fails, the other pane carries the load and prevents loss of cabin PRESSURE

Question 54

POLYSULPHIDE SEALING COMPOUND. APPLICATION

the sealant manufacturer may specify a minimum application ___________ for the sealant

Answer 54

POLYSULPHIDE SEALING COMPOUND. APPLICATION

the sealant manufacturer may specify a minimum application TEMPERATURE for the sealant

Question 55

PASSENGER SEAT ATACHEMENTS

passenger seats are attached to the floor beam mounted seat tracks by quick ________ fittings. these allow rapid changes to cabin __________ and seat pitch while maintaining the required cash resistance. galley and toilet compartments, crew seats, stowages, cabin dividers and internal bulkheads are also secured to the seat tracks.

the seat assemblies are secured in place by the rear track ___________ fitting. the seat group electronics box (SEB) is located, if fitted, under the seat and is provided with _____-loaded ________ locking plugs

Answer 55

PASSENGER SEAT ATACHEMENTS

passenger seats are attached to the floor beam mounted seat tracks by quick RELEASE fittings. these allow rapid changes to cabin CONFIGURATION and seat pitch while maintaining the required cash resistance. galley and toilet compartments, crew seats, stowages, cabin dividers and internal bulkheads are also secured to the seat tracks.

the seat assemblies are secured in place by the rear track ATTACHMENT fitting. the seat group electronics box (SEB) is located, if fitted, under the seat and is provided with SPRING-loaded POSITIVE locking plugs

Question 56

CARGO. COMPONENTS. ROLLERS AND BALL MATS

rollers and ball mats provide a ___ friction surface for the containers to move upon.

guide _______ are mounted to the side of the door _____ to centralise the containers as they run in and out of the door and so prevent door frame _______

sill rollers are mounted to the lower ____ frame to provide a rolling surface into and out of the door area

roller trays are mounted down the ______ length of the cargo bay, except for the ____ mat area. they provide a low friction surface for moving containers.

ball mats (or ball transfer panels) are mounted in the door area and are low friction devices for ease of container movement. a ______ loaded self lubricating steel ball which itself rides on small ball bearings in a cup shaped housing makes up the individual ball unit. a _____ ring prevents the ingress of dirt into the mechanism

Answer 56

CARGO. COMPONENTS. ROLLERS AND BALL MATS

rollers and ball mats provide a LOW friction surface for the containers to move upon.

guide ROLLERS are mounted to the side of the door FRAME to centralise the containers as they run in and out of the door and so prevent door frame DAMAGE

sill rollers are mounted to the lower DOOR frame to provide a rolling surface into and out of the door area

roller trays are mounted down the ENTIRE length of the cargo bay, except for the BALL mat area. they provide a low friction surface for moving containers.

ball mats (or ball transfer panels) are mounted in the door area and are low friction devices for ease of container movement. a SPRING loaded self lubricating steel ball which itself rides on small ball bearings in a cup shaped housing makes up the individual ball unit. a WIPER ring prevents the ingress of dirt into the mechanism

Question 57

CARGO. COMPONENTS. ROLL OUT STOPS

the purpose of the roll out stops shown, is to _______ the container rolling out of the cargo bay while it is on the ____ mat. the roll out stop has a lip guide and roller. as the container moves into the cargo door frame it contacts the lip guide roller and rotates the roll out stop ____ to allow the container to pass. after the container has entered the cargo bay the lip guide springs back to vertical to _______ the container sliding out

Answer 57

CARGO. COMPONENTS. ROLL OUT STOPS

the purpose of the roll out stops shown, is to PREVENT the container rolling out of the cargo bay while it is on the BALL mat. the roll out stop has a lip guide and roller. as the container moves into the cargo door frame it contacts the lip guide roller and rotates the roll out stop DOWN to allow the container to pass. after the container has entered the cargo bay the lip guide springs back to vertical to PREVENT the container sliding out

Question 58

CARGO. COMPONENTS. LATERAL GUIDES

they provide ______ control for the containers as they move into or out of the cargo bay.

to allow passage down the bay, the guides are ________, the ______ on top of the guide assists in container movement

Answer 58

CARGO. COMPONENTS. LATERAL GUIDES

they provide LATERAL control for the containers as they move into or out of the cargo bay.

to allow passage down the bay, the guides are RETRACTED, the ROLLER on top of the guide assists in container movement

Question 59

WING CONSTRUCTION

wings can be cantilever or semi-cantilever

a cantilever wing has all its structural strength ______ the wing structure and is attached to the fuselage at one end and requires no external _______. this type of wing is normally found on ____ performance aircraft and ________

the semi-cantilever wing obtains its strength ____ by internal structure and _______ bracing by struts. this arrangement allows a ______ wing structure. this type of wing is usually found on ______ aircraft and relatively slow aircraft designed to carry _____ loads.

Answer 59

WING CONSTRUCTION

wings can be cantilever or semi-cantilever

a cantilever wing has all its structural strength INSIDE the wing structure and is attached to the fuselage at one end and requires no external BRACING. this type of wing is normally found on HIGH performance aircraft and TRANSPORT

the semi-cantilever wing obtains its strength BOTH by internal structure and EXTERNAL bracing by struts. this arrangement allows a LIGHTER wing structure. this type of wing is usually found on SMALLER aircraft and relatively slow aircraft designed to carry HEAVY loads.

Question 60

WING RIBS

a wing rib is a ____ wise member of the wing structure used to give the wing section its shape. it also ________ the air loads from the skin to the spars

the ribs spaced at appropriate intervals along the wing spars also stabilise the spars against ________

the ribs may be of the _________ type made by pressing from sheet metal. these ribs are flanged around the edge and incorporate flanged lightening holes which _______ weight and _______ stiffness. alternatively, the ribs may be of the strut _______ type having separate ‘L’ or ‘T’ section extruded flanges (booms) riveted to ________ struts

Answer 60

WING RIBS

a wing rib is a CHORD wise member of the wing structure used to give the wing section its shape. it also TRANSMITS the air loads from the skin to the spars

the ribs spaced at appropriate intervals along the wing spars also stabilise the spars against TWISTING

the ribs may be of the DIAPHRAGM type made by pressing from sheet metal. these ribs are flanged around the edge and incorporate flanged lightening holes which REDUCE weight and INCREASE stiffness. alternatively, the ribs may be of the strut BRACED type having separate ‘L’ or ‘T’ section extruded flanges (booms) riveted to DIAGONAL struts

Question 61

LARGE TRANSPORT AIRCRAFT WINGS

the wing must be strong enough to carry its own ______ together with the weight of the ____ in the wings, the weight of _______ attached to the wings and the forces imposed by the _____ controls

Answer 61

LARGE TRANSPORT AIRCRAFT WINGS

the wing must be strong enough to carry its own WEIGHT together with the weight of the FUEL in the wings, the weight of ENGINES attached to the wings and the forces imposed by the FLIGHT controls

Question 62

WINGS. INTEGRAL FUEL TANKS

the wing structure which forms the integral tank will also incorporate fuel ____. these ensure that the fuel only runs from ________ to _______ through _____ valves or _____ valves which are incorporated in the dams. the fuel dams prevent large fuel ______ within the wing tanks when the aircraft is rolling etc.

Answer 62

WINGS. INTEGRAL FUEL TANKS

the wing structure which forms the integral tank will also incorporate fuel DAMS. these ensure that the fuel only runs from OUTBOARD to INBOARD through CHECK valves or CLACK valves which are incorporated in the dams. the fuel dams prevent large fuel SURGES within the wing tanks when the aircraft is rolling etc.

Question 63

WING TO FUSELAGE ATTACHMENTS

the weight of the fuselage on the centre wing box and the flight loads on the wing combine to produce a considerable ______ deflection of both wing ____ during flight.

although this deflection is ______ within the wing centre box, it is most important that the box section is designed in such a way that those wing deflections are not __________ into the fuselage structure.

on large transport aircraft the complete wing assembly centre box is usually fitted with _____ attachments which are attached to frames which form part of the fuselage centre section. the wing spar terminal fittings bolt ________ onto the wing box and the stringers are spliced to fittings on the wing box. in this way the ________ wall of the centre wing box is also the ______ wing rib

another method of attaching the wing centre box to the fuselage is by means of _____ links. one link at each corner of the wing centre box is connected to ________ frames. drag struts and spanwise body struts are fitted to the wing centre box and these are attached to the fuselage structure to ________ locate the wing but at the same time allowing slight vertical movement of the wing centre box as the tips flex up and down

Answer 63

WING TO FUSELAGE ATTACHMENTS

the weight of the fuselage on the centre wing box and the flight loads on the wing combine to produce a considerable UPWARDS deflection of both wing TIPS during flight.

although this deflection is SLIGHT within the wing centre box, it is most important that the box section is designed in such a way that those wing deflections are not TRANSFERRED into the fuselage structure.

on large transport aircraft the complete wing assembly centre box is usually fitted with FRAME attachments which are attached to frames which form part of the fuselage centre section. the wing spar terminal fittings bolt DIRECTLY onto the wing box and the stringers are spliced to fittings on the wing box. in this way the OUTBOARD wall of the centre wing box is also the INBOARD wing rib

another method of attaching the wing centre box to the fuselage is by means of SHORT links. one link at each corner of the wing centre box is connected to FUSELAGE frames. drag struts and spanwise body struts are fitted to the wing centre box and these are attached to the fuselage structure to POSITIVELY locate the wing but at the same time allowing slight vertical movement of the wing centre box as the tips flex up and down

Question 64

LANDING GEAR ATTACHMENTS.

the nose landing gear units are attached to __________ fuselage frames. structural _____ are often incorporated in the ____ landing gear attachments. these fuses provide points between the landing gear and wing spar __________ strong enough to handle ______ operating loads. however, these points will give way under _________ loads before damage to ________ structure can occur which could cause the _________ fuel tanks to rupture

Answer 64

LANDING GEAR ATTACHMENTS.

the nose landing gear units are attached to STRENGTHENED fuselage frames. structural FUSES are often incorporated in the MAIN landing gear attachments. these fuses provide points between the landing gear and wing spar ATTACHMENTS strong enough to handle NORMAL operating loads. however, these points will give way under EXCESSIVE loads before damage to PRIMARY structure can occur which could cause the INTEGRAL fuel tanks to rupture

Question 65

AILERON AND SPOILER ATTACHMENTS

flying controls such as ailerons and spoilers are connected to the wing rear spar by ________ hinge fittings. the hinge fittings may be mounted on the ____ itself, or on special ____ which transfer the loads to the spar, depending on the size of the wing. actuators are attached to ____________ structural members

Answer 65

AILERON AND SPOILER ATTACHMENTS

flying controls such as ailerons and spoilers are connected to the wing rear spar by MULTIPLE hinge fittings. the hinge fittings may be mounted on the SPAR itself, or on special RIBS which transfer the loads to the spar, depending on the size of the wing. actuators are attached to STRENGTHENED structural members

Question 66

VERTICAL STABILISER

construction of the vertical stabiliser or fin is generally _______ to the wing. on a typical large aircraft it will consist of forward and rear spars, ribs, stringers and stressed skins forming a torque box, with leading and trailing edge fairing assemblies, rudder hinge fittings, actuator attachments and access panels. stringers may be omitted on smaller structures as shown

the whole structure is connected to fittings on __________ in the fuselage empennage area. on large aircraft this joint is usually __________. on smaller ones, attachment may be by means of __________ pins which enable the fin to be removed for access, maintenance and transport.

‘T’ tailed aircraft, where the horizontal stabiliser is mounted at the top of the vertical stab, will require a stronger _______ box

Answer 66

VERTICAL STABILISER

construction of the vertical stabiliser or fin is generally SIMILAR to the wing. on a typical large aircraft it will consist of forward and rear spars, ribs, stringers and stressed skins forming a torque box, with leading and trailing edge fairing assemblies, rudder hinge fittings, actuator attachments and access panels. stringers may be omitted on smaller structures as shown

the whole structure is connected to fittings on BULKHEADS in the fuselage empennage area. on large aircraft this joint is usually PERMANENT. on smaller ones, attachment may be by means of REMOVABLE pins which enable the fin to be removed for access, maintenance and transport.

‘T’ tailed aircraft, where the horizontal stabiliser is mounted at the top of the vertical stab, will require a stronger TORQUE box

Question 67

HORIZONTAL STABILISER

the horizontal stabiliser may be designed as a _____ surface attached to the tailcone or fin, or it may be ______ at the rear spar and used as a _________ surface to provide _____ trim. in this case, the left and right stabilisers are jointed to a centre _______ box

Answer 67

HORIZONTAL STABILISER

the horizontal stabiliser may be designed as a FIXED surface attached to the tailcone or fin, or it may be HINGED at the rear spar and used as a MOVEABLE surface to provide PITCH trim. in this case, the left and right stabilisers are jointed to a centre TORQUE box

Question 68

CONTROL SURFACE STRUCTURE. AILERON, ELEVATOR AND RUDDER

whilst the aerofoil section of each control differs, the structure is essentially similar, being relatively _____ when compared with the main surface to which they are attached. the main structural element of the aileron is a ______ box consisting of the main and rear spars and the upper and lower skins. inter spar ribs brace the structure. a second torsion box is formed by the leading edge skin and the main spar and this is reinforced with nose ribs, particularly at the cut outs for the hinge points.

on many aircraft, a ____ is incorporated between the structure and the control surface. this improves the __________ efficiency and prevents the ingress of moisture and foreign objects

Answer 68

CONTROL SURFACE STRUCTURE. AILERON, ELEVATOR AND RUDDER

whilst the aerofoil section of each control differs, the structure is essentially similar, being relatively LIGHT when compared with the main surface to which they are attached. the main structural element of the aileron is a TORSION box consisting of the main and rear spars and the upper and lower skins. inter spar ribs brace the structure. a second torsion box is formed by the leading edge skin and the main spar and this is reinforced with nose ribs, particularly at the cut outs for the hinge points.

on many aircraft, a SEAL is incorporated between the structure and the control surface. this improves the AERODYNAMIC efficiency and prevents the ingress of moisture and foreign objects

Question 69

AERODYNAMIC BALANCE

aerodynamic balance is provided to ______ the pilot in moving the ______ surfaces

aerodynamic balance may take the form of a ____ tip, ______ tab or _____ tab

Answer 69

AERODYNAMIC BALANCE

aerodynamic balance is provided to ASSIST the pilot in moving the CONTROL surfaces

aerodynamic balance may take the form of a HORN tip, BALANCE tab or SPRING tab

Question 70

AERODYNAMIC BALANCE PANELS

some larger jet transport aircraft use aerodynamic balance panels. these provide very ______ help when the surface is deflected a _____ amount, but will ________ the amount of assistance that it gives as the surface deflection is _________

Answer 70

AERODYNAMIC BALANCE PANELS

some larger jet transport aircraft use aerodynamic balance panels. these provide very LITTLE help when the surface is deflected a SMALL amount, but will INCREASE the amount of assistance that it gives as the surface deflection is INCREASED

Question 71

CONTROL SURFACE MASS BALANCE

ailerons, elevators and rudders are mass balanced to prevent _______. flutter is a rapid oscillation of the control surface about its hinge line resulting in severe ________. the result of this is that the control surface, its attachments and the structure near the attachments can suffer _______ such as cracks or complete failure

it is very important that ________ in a tab operating system be kept to a minimum in order to reduce to possibility of control surface flutter. in the absence of any data from the aircraft manufacturer, the free play at the trailing edge of the tab should not exceed .% of the maximum chord of the tab

should it be necessary to repair or repaint a control surface at any time, it is essential that the mass _______ is checked in accordance with the aircraft maintenance manual, and adjusted if necessary

Answer 71

CONTROL SURFACE MASS BALANCE

ailerons, elevators and rudders are mass balanced to prevent FLUTTER. flutter is a rapid oscillation of the control surface about its hinge line resulting in severe VIBRATION. the result of this is that the control surface, its attachments and the structure near the attachments can suffer DAMAGE such as cracks or complete failure

it is very important that BACKLASH in a tab operating system be kept to a minimum in order to reduce to possibility of control surface flutter. in the absence of any data from the aircraft manufacturer, the free play at the trailing edge of the tab should not exceed 2.5% of the maximum chord of the tab

should it be necessary to repair or repaint a control surface at any time, it is essential that the mass BALANCE is checked in accordance with the aircraft maintenance manual, and adjusted if necessary

Question 72

TYPICAL CONTROL SURFACE MASS BALANCING PROCEDURE

when determining the additional weight of the repair, the weight of the material removed must be _________ from the total weight of new material fitted

Answer 72

TYPICAL CONTROL SURFACE MASS BALANCING PROCEDURE

when determining the additional weight of the repair, the weight of the material removed must be SUBTRACTED from the total weight of new material fitted

Question 73

SPOILERS AND SPEED BRAKES

these are generally simple hinged panels constructed from light _____ sheet and/or ________ material stiffened by a thick honeycomb core. the actuator and hinge fittings are forged or cast aluminium alloy and local ___________ around them is provided by internal doubler plates or composite plies

Answer 73

SPOILERS AND SPEED BRAKES

these are generally simple hinged panels constructed from light ALLOY sheet and/or COMPOSITE material stiffened by a thick honeycomb core. the actuator and hinge fittings are forged or cast aluminium alloy and local STRENGTHENING around them is provided by internal doubler plates or composite plies

Question 74

ADVANTAGES OF THE PYLON ARRANGEMENT

the main advantage of the pylon mounted engine arrangement is that it _______ the wing bending moment, since the engine weight partly offsets the upward force due to wing lift. this results in a saving in ______ of the wing structure.

like vortilons, engine pylons generate a _____ over the upper wing surface at large angles of attack preventing wing tip ________

Answer 74

ADVANTAGES OF THE PYLON ARRANGEMENT

the main advantage of the pylon mounted engine arrangement is that it REDUCES the wing bending moment, since the engine weight partly offsets the upward force due to wing lift. this results in a saving in WEIGHT of the wing structure.

like vortilons, engine pylons generate a VORTEX over the upper wing surface at large angles of attack preventing wing tip STALLING

Question 75

PYLON STRUCTURE AND WING ATTACHEMENTS

the structure of a pylon generally consists of top and bottom _____ separated by vertical ribs and clad with skins attached to the spars and ribs. the materials used include aluminium alloy, stainless steel and titanium. a ________ on the bottom of the pylon protects it from exposure to high __________ and fire _____. the pylon fairings are usually made from composite honeycomb.

the attachment pins are known as structural _____ and are designed to fail at a predetermined stress and permit the loss of an _____ without damage to the wing in cases of severe engine damage resulting in _________

panels or hinged doors are provided on the lower pylon structure to give access to the various services within. hinged ____ ___ panels are provided to relieve pressure caused by a leaking air _____. these panels are lightly latched by spring pressure and are designed to open if the pressure in the pylon builds up to about _psi. the aircraft maintenance manual gives the procedure for checking the opening of these doors

Answer 75

PYLON STRUCTURE AND WING ATTACHEMENTS

the structure of a pylon generally consists of top and bottom SPARS separated by vertical ribs and clad with skins attached to the spars and ribs. the materials used include aluminium alloy, stainless steel and titanium. a FIREWALL on the bottom of the pylon protects it from exposure to high TEMPERATURES and fire DAMAGE. the pylon fairings are usually made from composite honeycomb.

the attachment pins are known as structural FUSES and are designed to fail at a predetermined stress and permit the loss of an ENGINE without damage to the wing in cases of severe engine damage resulting in VIBRATION

panels or hinged doors are provided on the lower pylon structure to give access to the various services within. hinged BLOW OUT panels are provided to relieve pressure caused by a leaking air DUCTS. these panels are lightly latched by spring pressure and are designed to open if the pressure in the pylon builds up to about 2psi. the aircraft maintenance manual gives the procedure for checking the opening of these doors