11.3 - Aircraft Structures Aeroplanes Flashcards
How far apart are frames spaced?
20 inches
What is the purpose of clips on the inner surface of the skin?
To transfer pressure loads from the skin to the frame to assist with compression
What can floor beams help carry? [3]
- Pressure loads across the fuselage
- support cabin pressurisation
- absorb normal loads from seat tracks
What can floor-to-skin shear ties assist with?
Provide an additional path for distributing cabin pressure loads
What part of the construction carries the primary loads?
The skin
Where is the keel beam located?
Through the centre wing section
What does the keel beam do?
Support the wheel well area where a maximum amount of bending can occur and transport wing loads.
What does the centre section of the fuselage provide? [2]
- Part of the cabin
- A structure for joining centre wing box and main landing gears together
How is the tail section constructed? [3]
- Frames
- stringers
- skin
When is a faying surface seal used?
Where it is difficult to seal after assembly
How is a good faying surface seal established?
When there is a small amount of sealant extruding from both sides of the joint
What is a fillet seal?
Bead of extrudable sealant to seams, joints and intersecting planes or surfaces
How is a satisfactory fillet seal indicated? [3]
- Smooth appearance
- free of voids, bubbles
- no overlaps
What are injection seals used for?
Fill holes, joggles, channels and other voids
What is used to seal control runs?
Control run sealing
What must control run seals be?
Tight enough to prevent pressure loss but not enough to hinder movement
What two types of sealing is there for doors? [2]
- Flap-type mechanical seal
- Diaphragm seals
How do flap type mechanical door seals work?
Comes into contact with the fuselage and creates a pressure and weather seal
How are diaphragm seals attached?
On the inside of the upper and lower gate hinges
On airbus, what might you find in the door seal?
Pressurisation holes
How are seats fitted in the aircraft?
Attached to seat tracks that run longitudinally
What does ULD stand for?
Unit load device
What is an anti roll out device?
Automatically retracts when hit by an ULD from outboard the aircraft.
Prevent backward movement once onboard the aircraft
What are the 5 different types of doors?
- Main entry doors
- service doors
- cockpit doors
- cargo doors
- emergency exit doors
Which door side of the aircraft is mainly used by services?
The right
How are aircraft doors numbered?
Numbered 1 to x, right and left have same numbers
What else can passenger doors be used as?
Emergency exit doors
Where is the bulk cargo door located?
Aft lower right side of the fuselage
What is the basic construction of a door? [3]
- Lower lining
- centre lining
- upper lining
What will you find in the lower lining of a door? [3]
- Escape Slide
- survival kit
- houses the pressure gauge viewing window
What will you find in the centre lining of a door? [2]
- Covers the door structure and latch mechanism
- incorporates the window, assist handle, access cover and interior door handle
What will you find in the upper lining of a door? [2]
- Covers door structure and latch mechanism
- houses escape slide lamp
What forms the construction of a door? [5]
- Frame
- upper and lower gate
- beams
- formers
- intercostals
What is a pressure stop?
It holds the door in position when the cabin is pressurised and help adjust the door to its correct position
What are the Boeing and airbus door suspension mechanisms?
- Boeing = hinge mechanism
- Airbus = door support system
What is the construction of the airbus door support system? [4]
- Support arm
- lifting lever
- upper link
- guide arms
What is the purpose of the lifting lever in doors?
Enables the door to be lifted
How is the door supported and maintained parallel to the fuselage?
Via the support arm and guide arms
What does the support arm house? [3]
- Damper
- emergency operation cylinder
- door stay mechanism
What does the door stay mechanism do?
Locks the door once it is in its fully open position
What is the construction of a Boeing hinge door mechanism? [3]
- Door torque tubes
- body torque tubes
- hinge arms
What is the main function of the door torque tube?
To rotate the door to a cocked position by transmitting handle torque to the upper and lower hinges
On which aircraft manufacturer, will you find a gear box within the door, so that when operating the door handle from the interior, that the exterior door handle doesn’t move?
Airbus
What types of emergency doors are there? [4]
- Main entry doors
- upper deck doors
- emergency hatches
- over head hatch
What do main entry doors have to aid them in opening during an emergency?
Power assist system
What will happen if you open a door in the “flight” position?
Emergency slides will deploy
What two modes will you find on the mode selector?
Flight and park
What does the mode selector have to prevent an intermediate position of the level?
Over centre spring
How are emergency slides connected?
To the girt and girt bar
How does the girt bar work?
The girt connects the slide to the girt bar and one end is wrapped around the girt bar
What is the power reservoir used for?
In an emergency to help open the door quicker and easier
When must you remove an emergency power reservoir?
When it has been used or if the pressure is low
What is the green indication on the pressure gauge of the door, not an indication of?
Sufficient pressure
What must you do when working with or around the emergency power reservoir?
Ensure safety pins are installed
What doors are commonly found in the main cabin with no hinges?
Overwing emergency hatches
What other name is there for over wing emergency hatches?
Plug door
What is found in the lower part of the cockpit door?
Decompression and evacuation flap
What opens the door in case of cockpit decompression?
3 electric release strikes are deenergised unlocking the doors
Where are the cargo bay doors located? [3]
Right hand lower fuselage:
- forward
- aft
- bulk (aft)
What is unique about the bulk cargo door, in comparison to the forward and aft doors?
Opens inwards and operated manually
What are the construction of the aft and forward cargo doors? [4]
- Door suspension
- master latch lock mechanism
- latch mechanism
- hook mechanism
What ensures alignment of the latches on a cargo door?
Centring roller on the bottom side of the door
How is the cargo door suspended?
Attached externally to the door and the fuselage
How is the bulk cargo door suspended?
Attached to its upper edge to the fuselage by 2 hinge arms
What connects the hinge arm to the ceiling of the cargo compartment in a bulk cargo door?
A snubber
How many pressure relief doors are there for the cargo door?
2
What is the master latch lock mechanism?
A safety mechanism that locks the master latch in position
How the master latch lock mechanism actuated?
By the cargo door handle
What happens when the master latch lock mechanism is actuated?
The handle movement is transmitted to the master latch lock torque tube, and the relief door torque tube by push rods and cranks
What must open first when operating the handle of the cargo door?
Pressure relief doors
What does the safety mechanism house? (Airbus) [2]
- Safety shaft
- 6 safety cams
What else does the safety shaft also move during opening?
Vent doors for pressure relief
By how much psi will the vent doors open if there’s a differential pressure?
1 psi
What mechanism do Boeing use for cargo door operation?
Hook and lifting mechanism
How are the hooks connected for the hook and lifting mechanism?
Connected to hook torque tube
What does the hook do during closing?
Guides the cargo door into position before the latches engage
What does the lift mechanism consist of? [4]
- Lift power unit
- gearbox and brake assemblies
- rotary actuators
- rotary actuator links
On airbus aircraft, how are cargo doors operated?
Hydraulically
What type of windows are there? [3]
- Cabin windows
- flight deck windows
- observer windows
What are the purpose of windows?
Allow maximum visibility for passengers and flight crew and holding cabin pressure
What do flight deck windows have additional protection against?
Bird strikes
How are flight deck windows numbered?
Left 1, right 1, left 2….
Symmetrically
What are the number 2 flight deck windows called?
Direct vision windows
What can number 2 flight deck windows be used for?
Emergency exits
Where can the heating film be found on flight deck windows?
On the inner surface of the outer glass
What is the construction of flight deck windows?
Strengthened glass of the outer side of the window, with 2 layers of chemically strengthened glass, bonded together with polyurethane
What are number 2 and 3 windows constructed of?
2 layers of stretched acrylic glass
How is the number 2 window installed?
From inside the flight deck
How are is number 1 and 3 windows installed?
Externally, attached to the aircraft frame.
A retainer holds the pane in place
What is placed between the windows and the frame?
Silicon seal to bond them together
What does the inner pane of the cabin windows have?
A small vent hole to ensure pressure between cabin and lanes are the same.
Why is there 2 cabin window panes?
In case one fails, the other can carry the pressure
What 3 areas make up the wing structure?
Left, centre and right wing boxes
What do the front and rear spars of the wing boxes do?
Act as walls for the fuel tank and to contain fuel
What is the construction of the outer wing boxes? [4]
- Front and rear spar
- ribs
- upper and lower stringers
- upper and lower skin panels
What may you find in the lower wing skin panels?
Access doors and openings located between wing ribs
What are the spars of the wings designed to do?
Carry loads
What can be found on the front spar? (3)
- Vertical stiffeners
- upper and lower chord angles
- a spar web
In addition to what you can find on the front spar, what else can you find on the rear spar of the wing?
Landing gear support arm (false rear spar)
What does the false rear spar do?
Distributes main landing gear loads to the rear spar of the wing and to the fuselage
What loads are ribs capable of carrying? [3]
- Torsion
- compression
- shear
What is in the structure of the leading edge? [3]
- Stiffeners
- ribs
- upper and lower skin panel
What does the trailing edge structure support?
The flight controls and their operation
What is the structure of the trailing edge? [4]
- Ribs
- stiffeners
- beams
- skin panels
What does the centre wing box do?
Distribute different loads across the fuselage and house the fuel tank
What can be found at the empennage? [3]
- Vertical and horizontal stabilisers
- dorsal fin
- rudders and elevators
What can the horizontal stabiliser sometimes be used as?
Fuel tank
How can the horizontal stabiliser be constructed?
Single piece or 3 piece structure
How are the elevators attached?
Hinge fittings
What is used to create a smooth incline to the vertical stabiliser?
Dorsal fin
What 2 types of hinges are there?
Primary and normal hinges
What do both type of hinges have? [3]
- Ball bearings to compensate for misalignment,
- Inner and outer bolt for fail-safe
- Sleeves to prevent over stress
What is difference in sleeves on primary and normal hinges?
Primary hinge only has 1 sleeve
What does the sleeve do on the hinges? [2]
- Allows the hinge to compensate for expansion and contraction of temperature change,
- Prevents a fixed position in relation to the hinge forks
Are the sleeves for the hinges interchangeable?
No
How can surface flutter be prevented?
If the control surface is hydraulically powered or by static balancing
What is static balancing?
Where balance weights are fitted forward of the hinge line to offset the mass of the control surface
What must be done to the control surface if it repaired in relation to static balancing?
Additional weights to be added
How are the deflection angle measured on all control surfaces?
Measured in relation to the zero position
How is the deflection angle measured for the aileron?
Angle between the wing reference plane and surface reference plane
How can the angle of the rudder or elevators be measured?
By using an inclinometer or measuring the distance between zero and the trailing edge
What should be done if you were to be working on a control surface?
Warning signs and safety devices to prevent inadvertent retraction
What is the main function of the pylon?
To carry loads from the engine to the torque box
What is another name for the pylon
The strut
What forms the assembly of the nacelle strut? [5]
- Torque box
- firewall and fire-seal
- strut drains
- fan cowl support beam
- engine attach fittings
What is the aft pylon fitting made by?
2 shackles
What prevents the movement of flames through the engine during an external engine fire? [4]
- Firewall
- fire seals
- flame proof panels
- diaphragms
How are the engines attached to the pylon
Via the front and aft engine mounts
What does the forward engine mount have?
Support beam assembly connected to the pylon by 4 attachment bolts
What type of construction are engine mounts?
Fail safe
Why aren’t axial loads transferred to the pylon from the engine in the aft engine mount?
Spherical bearings at the links
