Airframes 2

Question 1

Airframe sections

Answer 1

Fuselage
Tailplane
Fin
Wing
Power plant
Undercarriage

Question 2

Bending load

Answer 2

Tensile load tries to stretch
Compression load tries to shorten

Question 3

Torsional load

Answer 3

Tries to twist structure
Long flat more susceptible than think rounded

Question 4

Shear load

Answer 4

Sliding of one part over another
Common on rivets bolts and fasteners

Question 5

Fuselage loading

Answer 5

Bending and shear loads during flight
Pressurisation adds tensile load
Also experiences torsion which results in further shear stress
Shear stress is two pieces bolted together wanting to go opposite directions

Question 6

Fuselage construction types

Answer 6

Truss (internal load bearing structure covered by non load bearing skin)
Uses longerons, struts, fairing strips and bulkheads
Upper and lower horizontal members react to bending diagonal react to shear loads
Monocoque (no internal framework skin bears full load)
Compression buckling can be a problem
Semi monocoque (skin reinforced and stabilised by internal framework both load bearing)

Question 7

Semi monocoque fuselage

Answer 7

Longerons and stringers horizontal help take bending loads frames vertical
Skin takes shear loads and some bending as well as pressurisation (tensile)

Question 8

Fuselage shape

Answer 8

Square or rectangle means non pressurised
Circular can be pressurised

Question 9

Wing configuration

Answer 9

Biplane (high and low wing)
Braced monoplane(one long wing with braces)
Cantilever (no bracing)

Question 10

Wing loading cantilever

Answer 10

Wing subject to bending shear and torsional loads
Direction of bending changes whether on ground or in flight
Torsion results from distance between cog and cop

Question 11

Fatigue

Answer 11

Function of load (how much force is applied) and cycles (number of times force is applied)
Signs of fatigue composite : delaminating and cracking
Signs of fatigue metal: cracking corrosion (rust)

Question 12

Damage from heavy landing (aluminium alloy)

Answer 12

Stressed tyres
Scraping on wheel rim
Bent axles
Bent struts
Buckling at u/c attachments
Buckling if firewall
Tail strike

Question 13

Operating outside flight envelope

Answer 13

Rippling of wing and fuselage skins
Buckling of internal structures

Question 14

Composite damage

Answer 14

Vibration stresses
Minor impact loads (bugs)
Bird strike
Hangar rash
Mishandling

Question 15

Fabric damage

Answer 15

Torn fabric
Worn fabric
Up damage
Mould

Question 16

Wing construction

Answer 16

Typically 2 spars consisting of spar caps and spar webs (caps connect to skin web connects to caps)
Carry wing bending loads
Front and rear keel lift envelope in the middle

Question 17

Loading of wing components

Answer 17

Webs carry shear loads
Stringers assist caps with bending loads and stabilise skin against buckling
Ribs maintain aero foil shape and transfer loads to spars
Skin transfers air loads onto ribs stringers and spars
Spar webs and skin form torsion box which resists twisting

Question 18

Wing struts

Answer 18

Assist with bending load (allows wing to be lighter than cantilever)
Will always be in tension or compression
Struts increase drag

Question 19

Flight controls

Answer 19

Primary
Similar to wing construction but with one spar

Secondary
Flaps and trim tabs

Tertiary
Slats etc

Question 20

Bell crank

Answer 20

Lever who’s two arms form a right angle
Decreases friction and stress on wiring turning corner

Question 21

Ground steering

Answer 21

Steerable or castoring
Da40 castoring

Question 22

3 types of braking system

Answer 22

Independent: hydraulic pressure directly proportional to force applied by pilot (for light ac)
Boosted: additional hydraulic pressure from main system boosts brake power
Power brake: brake control valve and hydraulic pressure from main system regulated by pilot force