11.3 Airframe Structures Flashcards by Meg Bazeley

What are the two types of aircraft fuselage construction?

. Monocoque
. Semi - monocoque

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What does a monocoque construction consist of?

. Frame assemblies and bulkheads to give shape to fuselage
. Skim to contain cabin pressure

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What is the main disadvantage of a monocoque construction?

Trying to maintain strength whilst being within weight limits

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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

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What is the normal spacing of frames in a construction?

20 inches apart

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What do bulkheads do?

Bulkheads carry and distribute different loads and fuselage

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What do pressure bulkheads do?

Withstand cabin pressure

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What is the purpose of a stringer?

Gives shape and carry stresses such as: banding, torsion and cabin pressure loads

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How are stringers connected to each other?

By stringer splices

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What is the main purpose of a clip on inner surface of skin?

Transfer pressure loads from skin panel to the frame

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How do floor beams lay?

Lay horizontally, adjacent to the skin panel

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Where are shear ties placed and why?

They extend along the two side of fuselage
Provides extra oath for distribution of cabin pressure loads

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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

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What does the centre section provide?

A structure for joining the centre wing box and main landing gears together

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The tail section of the aircraft is designed to take loads from where?

The empennage

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When is a flaying surface seal applied?

During manufacture,
Impossible to apply after assembly

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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

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When are fillet seals used?

To seal seams, joint and intersecting plane/ surfaces

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When is a fillet seal satisfactory?

When the fillet overlaps the seam by required dimension

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When would you use an injection seal?

To fill holes, channels and joggles

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Why do we fastener seal?

. To make a fluid tight seal
. Minimise corrosion
. Improve join strength

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When are control run seals (pressure sales) used?

When cables/rods move through pressure bulkheads, to prevent air pressure loss

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As well as flying control run sealing, what else needs to be pressure sealed?

Wires and cables

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What two types of seals are used in main entry doors?

. Flap type mechanical seals
. Diaphram seals

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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?

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