Aircraft Rigging and Symmetry Checks

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Questions and Answers

Briefly describe the two types of rigging on aircraft?

a) Aircraft structure must be rigged for correct alignment of all fixed components. b) Rigging for alignment of control surfaces and the controls which move the surfaces (aileron, rudder, and elevator).

Describe the term "wash-in"?

a) Wash-in is the increase in the angle of incident from the root to the tip. Washing in would give the wing an increased lift. b) Wash-in will result the wing having higher angle of incident at the tip compare to the wing root. c) Was-in will also result in the wing tip will stall before the wing root.

List with pictures three different kinds of symmetry checks on aircraft?

The three different types of symmetry checks on aircraft are: a) Checking Verticality of Fin b) Using Straight Edge and Adjustable Level with Incidence Board c) Using Special Dihedral Board With Spirit Level Incorporated (See the image in the original document for reference).

What do you need to ensure before rigging is carried out?

a) A level site capable of bearing the load to be applied should be selected for the operation otherwise, where trestles are used, it may not be possible to level the aircraft, and where jacks are used, the danger of the jacks toppling and dropping the aircraft would exist. b) Leveling and Rigging checks should not normally be undertaken in the open, but if this is unavoidable, the aircraft should be positioned nose into the wind. In any case, the aircraft should not be lifted in strong wind or gusts. c) All equipment which may cause damage to aircraft should be moved away and no personnel other than those directly connected with that operation should be permitted on or around the aircraft. Signup and view all the answers

Name three equipments/tools needed for ensuring the straightness/level/alignment of an aircraft?

a) Plumb Bob and Target b) Inclinometer c) Theodolite d) Sighting rod Signup and view all the answers

What are the 5 common types of stresses that an aircraft carries? Name one practical airframe structural example for each type of stress?

<ol> <li>Torsion: Longerons in the fuselage area will experience torsion force whenever the aircraft is rolling.</li> <li>Tension: Wing, whenever the aircraft is on ground, the top surface of the wing will experience tension force.</li> <li>Compression: Wing, whenever the aircraft is on ground, the bottom surface of the wing will experience compression force.</li> <li>Bending: the wing will experience bending stress because the wing is fixed to the fuselage of the aircraft at the wing root while near the wing tip; the wing is loaded with engine. (Cantilever)</li> <li>Shear: The wing root attached to the fuselage of the aircraft will experience hearing stress during flight as it is subjected to forward thrust of the aircraft.</li> </ol> Signup and view all the answers

Define Stress?

Stress is defined as the amount of force acting on a unit surface area of a body. Stress = Force / Area Signup and view all the answers

Define Bearing Stress?

Bearing stress is defined as the compressive stress acting on a surface of a body where load are applied. It is commonly occurs at the point of support. Signup and view all the answers

What are the 2 types of stress that an aircraft cabin experiences during cabin pressurization?

Circumferential/Hoop stress and longitudinal stress that are acting on the frame of the aircraft. Signup and view all the answers

Define Hooke's Law?

The degree of strain in a material is proportional to the stress as long as the elastic limit is not exceed is known as Hooke's Law. For relatively small deformation of an object, the displacement or the size of the deformation is directly proportional to the force. Force = K*dx Signup and view all the answers

Define Yield Stress?

When stress has gone beyond the elastic limit at which deformation continues without additional stress is called the yield stress. Signup and view all the answers

Define Fatigue Stress?

Fatigue is the accumulation effect of cyclic loading for a long period of time which cause the material of the aircraft to weaken. Signup and view all the answers

Define Low Cycle Fatigue and state 1 practical example?

LCF is caused by large loading over a long period of time or over a large and slow frequency of movement. Example is the wing of the aircraft fluttering in the air. Signup and view all the answers

If the ultimate tensile strength of material to be used for fabricating a structure is 600 MPa, and a safety factor of 1.25 (or 25%) is applied, what is the maximum design load that the material can carry?

600/1.25 = 480MPa Signup and view all the answers

If a material of an aircraft is to carry 800MPa of load, given a safety factor of 1.5, what should be the ultimate tensile strength of the material?

800 x 1.5 = 1200Mpa Signup and view all the answers

Calculate the maximum design shear, tensile, tear-out and bearing force given Rivet (2117 Aluminium Alloy) with Diameter - 6mm and Ultimate Shear Strength, Ts – 217MPa and Sheet Metal Plate (6061-T6 Aluminium Alloy) with Plate Thickness - 2mm, Ultimate Bearing Strength, Pb – 607 MPa, Ultimate Tensile Strength, Pt – 310 MPa, Ultimate Shear Strength, Ps – 207 MPa and Rivet position Rp - 25mm from all edges

Shear Force: Fs = 6135.53N Tensile Force: Ft = 27280N Bearing Force: Fb = 7284N Tear Out Force: F = 18797.256N Signup and view all the answers

Which of the above forces will likely cause damage to the lap joint earliest? And why?

The most probable forces that will cause damage to the lap joint earliest should be the Bearing force. This is because the maximum bearing load that the material can sustain is the lowest among the 4 failure modes forces. Signup and view all the answers

Flashcards

Aircraft Rigging

Ensures correct alignment of fixed components and control surfaces (aileron, rudder, elevator).

Wash-in

Increase in the angle of incidence from wing root to tip, increasing lift and causing the wing tip to stall before the root.

Pre-Rigging Checks

Ensuring the aircraft is on a level surface capable of bearing the load, protected from strong winds, and clear of unnecessary equipment/personnel.