11.3 Airframe Structures Flashcards
What are the two types of aircraft fuselage construction?
. Monocoque
. Semi - monocoque
What does a monocoque construction consist of?
. Frame assemblies and bulkheads to give shape to fuselage
. Skim to contain cabin pressure
What is the main disadvantage of a monocoque construction?
Trying to maintain strength whilst being within weight limits
A semi- monocoque construction can withstand higher damage and strength than a monocoque… why is this?
Because the stringers, frames and additional clip share the load with the skin
What is the normal spacing of frames in a construction?
20 inches apart
What do bulkheads do?
Bulkheads carry and distribute different loads and fuselage
What do pressure bulkheads do?
Withstand cabin pressure
What is the purpose of a stringer?
Gives shape and carry stresses such as: banding, torsion and cabin pressure loads
How are stringers connected to each other?
By stringer splices
What is the main purpose of a clip on inner surface of skin?
Transfer pressure loads from skin panel to the frame
How do floor beams lay?
Lay horizontally, adjacent to the skin panel
Where are shear ties placed and why?
They extend along the two side of fuselage
Provides extra oath for distribution of cabin pressure loads
Where is the keel beam located and why do we have it?
. Located through the centre wing section of fuselage
. Supports wheel well where bending occurs
What does the centre section provide?
A structure for joining the centre wing box and main landing gears together
The tail section of the aircraft is designed to take loads from where?
The empennage
When is a flaying surface seal applied?
During manufacture,
Impossible to apply after assembly
When would you know that the flaying surface sealant is satisfactory?
When a small amount of sealant is extruded in both sides of joint after assembly
When are fillet seals used?
To seal seams, joint and intersecting plane/ surfaces
When is a fillet seal satisfactory?
When the fillet overlaps the seam by required dimension
When would you use an injection seal?
To fill holes, channels and joggles
Why do we fastener seal?
. To make a fluid tight seal
. Minimise corrosion
. Improve join strength
When are control run seals (pressure sales) used?
When cables/rods move through pressure bulkheads, to prevent air pressure loss
As well as flying control run sealing, what else needs to be pressure sealed?
Wires and cables
What two types of seals are used in main entry doors?
. Flap type mechanical seals
. Diaphram seals
How does a flap type seal work?
Attached around the door when door closed and latched, the seal contacts the fuselage frame and forms a pressure and weather seal
How does the diaphram seal work?
Seal is attached on inside of upper and lower gate hinges
The seals flex when gates open/ close
When are seat tracks known as?
L track or ltrack
Why do seat tracks enable moving the seats?
To provide adjustable legroom depending on the airline
What does ULD stand for?
Unit load device
What is a unit load device?
A pallet/container used to load luggage so can be bundled into a single unit
What does ARO stand for?
Anti roll out device
Why do we have AROs?
It automatically retracts when hit by an ULD
What are the 5 types of doors?
. Main energy doors
. Service doors
. Cockpit doors
. Cargo doors
. Emergency doors
Is the left or right hand doors used for passenger doors?
Left = passenger doors
Right = service doors for galleys etc
How are the main energy doors numbered?
From nose to tail
One left, two left
One right, two right
How many over- wing emergency hatches are there on each side of the aircraft?
1 or 2
Size depending
On a passenger door what does the lower lining cover/ house.
Covers - the escape slide and survivable kit
Houses - pressure gauge window
What does the centre lining of the door incorporate?
The window, assist handle, access cover and interior handle
What are the different selector lever modes for airbus and Boeing?
Boeing = park and flight
Airbus = manual and automatic
When the cabin is pressurised and door is closed what holds the door there?
Pressure stop pin and fitting
On a type 1 door locking mechanism, if the emergency system is auto deactivated when exterior handle is pull in which direction?
Pulled outward
What does the overhead hatch door provide?
An emergency exit for flighty crew from cockpit
When the mode selector level is in automatic or flight position what does it mean?
It’s in an armed position
When mode selector level is in manual or park position, what does it mean?
System not armed, slide doesn’t inflate/ deploy
What is the lock out mechanism?
Prevent the door changing from manual or automatic when doors is open
What is the emergency slide connected by?
By a girt and girt bar
Where is the slide and girt bar?
Inside the door lower lining
What gas is emergency power reservoir pressurised by?
Nitrogen
When must you remove the emergency power reservoir?
After it has been used or if pressure is low
What is the most common type of over wing hatch called?
Plug door
How does a plug door mechanism works?
The hatch is larger than the out aperture it fills and once the locking mechanism is realised the hatch Is lifted inboard then stowed or turned sideways.
A cockpit door that is resist to small penetration and able to be locked is fitted on what aircraft?
Passenger carrying aircraft that weights more than 45500kg or greater seat capacity of 60 people
What is the main material of a cockpit door?
Kevlar
What does the cockpit door consist of?
Lower part =decompression and evacuation flap
A lock for when aircraft is powered up
A spy hole
How does the bulk cargo door open?
Opens inward and operated manually
What is the purpose of the master lock mechanism?
A safety mechanism that locks the master latch in position
Before you open the cargo door what must you ensure?
The power light on the panel is illuminated
What colour does the light illuminated when the cargo door is fully opened?
Green
To use a hand pump in a cargo system to pressurise the system, what does the selector lever must be in?
Manual mode
What do all windows allow?
Maximum visibility for passengers and crew, as well as holding cabin pressure
What does the flight deck give additional protection over?
Bird impact and ice build up
What are the two fwd flight deck windows known as?
Flight deck windscreen
What glass is found on the outer side of the flight deck windscreen?
Thermally strengthened glass
What are the two inner layers of flight deck windscreen made of?
Special acrylic glass
What are all the .Ayers of flight deck windscreen bonded together by?
Polyurethane
(Special plastic)
How are the sliding windows installed ?
From the inside of flight deck
And move on rails
How are the fixed windscreens installed
Externally
The passenger windows have two panes of special acrylic glass with a small hole in the middle of the inner pane, why?
That pressure between the panes is the same as cabin pressure
What are the 3 main areas of the wing structure?
. Centre wing box
. Left wing box
. Right wing box
The skin panels form the exterior surface of the wing, what are they reinforced by?
Stringers on the inner surface of the skin
What load does the lower wing skin mainly carry?
Tension loads
What loads does the upper wing skin mainly carry?
Compression loads
How are spars connected to the skin panels?
By bolts and rivets
Explains ribs in a wing?
They lie diagonally and are able to carry torsion, compression and shear loads.
Also give shape to allow wing to be able to provide walls for fuel tanks
What is the nose cap of the leading edge normally made from?
Aluminium alloy, with the rest being made from composite
What does the centre wing box do?
Distributes different loads to the fuselage and can house fuel
What does the empennage consist of?
. Vertical stab
. Horizontal stab
. Dorsal fin
. Rudders
. Elevators
. Tail section/ cone
Is the empennage pressurised?
No it is unpressurised
Explain the tail cone
It is a removable unit which has a compartment for the APU
What is the purpose of the horizontal stabiliser?
Pitch trim control
How can the horizontal stabiliser be constructed?
1 or 3 piece structure
What joins the vertical stabiliser to the fuselage smoothly?
The dorsal fin
Where is the vertical stabiliser located (fin)?
At the top of the tail section
What do the rudders provide?
Directional control
How is the rudder attached to the vertical stabiliser?
Attached to the trailing edge of the fixed vertical stabiliser
What is the purpose of hinges for flight control surfaces?
Connect the flight control surfaces to the adjacent structure
What are the two types of hinges?
. Primary/ master = (stable position, has extra but in picture)
. Normal = (side ways, is missing the extra bit)
How can surface flutter be prevented on control surfaces?
. Hydraulically powered
. Static balancing in mechanical controlled
What is the process of static balancing?
Weights are fitted in front of the hinge line to off set the mass behind the hinge line
Before the elevators can be in the 0 position, what needs to happen?
The movable stabiliser must be in the 0 position
When work is in process on the surfaces or actuators what needs to be done?
Warning signs
When flight control surfaces are repaired what needs to happen?
Static balancing
What is the pylon assembly divided into?
. Primary structure
. Secondary structure
How many areas is the torque box attached to on the wing?
3 areas on the wing
2 fwd and 1 aft
What is the purpose of the pylon?
To attach the engine to the airframe/ wing
How many attachment points does the pylon have to the wing?
3
The fan cowl support beam extends forward of what?
The torque box
What assembly does the torque box belong to?
Primary structure
What is the torque box made up of?
Spars, ribs, stiffners and side panels
What is another name for the pylon?
The strut
How is the engine equipped til the pylon?
By fwd and aft engine mounts
How many bolts attaches the fwd engine mount to the pylon?
4 bolts
The construction of the fwd engine mount is also….?
Fail safe
What is the purpose of a nacelle?
A streamlined pod/ encloser to house the engine and its components
How do you protect vunereble parts of aircraft structure form heat from the gas engine turbine?
Firewalls
