General/Airframe Problem Oral Questions

Question 1

What is a balance trim tab?

Answer 1

It is an auxiliary control designed to create aerodynamic forces to assist in moving a control surface. When the primary control surface is moved in any direction, the tab automatically moves in the opposite direction, helping pilot move the control surface

Question 2

What is a servo trim tab?

Answer 2

It is an auxiliary control, positioned by the movement of a cockpit control and designed to create aerodynamic forces to assist in moving a control surface.

Question 3

What is a spring tab?

Answer 3

It is an auxiliary control designed to aid the movement of a primary control at high speeds when control forces become too high

Question 4

What are the two reasons for installing a lightening hole in a sheet metal wing rib?

Answer 4

Lightening holes reduce the weight and increase stiffness

Question 5

Describe the markings found on the heads of A, B, D, AD, and DD rivets

Answer 5

A rivets are plain, B rivets have a cross, D rivets have a raised dot, AD rivets have a dimple, and DD rivets have a double dash

Question 6

How can a mechanic determine whether the countersink for a flush rivet should be dimpled or drilled?

Answer 6

By the thickness of the top sheet- thin sheets are dimpled while thick sheets may be countersunk

Question 7

Name several methods for forming sheet metal.

Answer 7

Bending or folding ,

stretching,

shrinking,

bumping, and

crimping

Question 8

If a 2024 rivet must be replaced with a 2117 rivet, how do you determine the size to be used?

Answer 8

For 5/32” or smaller diameter, use the next larger size, as long as edge distance and spacing meet minimums

Question 9

What are the dimensions of a properly formed rivet head?

Answer 9

The head should be 1.5 times the shank diameter in width and 1/2 the shank diameter in height

Question 10

What minimum edge distance and spacing should be used for a single row of protruding head rivets?

Answer 10

At least two rivet diameters from the edge and not less than three rivet diameters apart.

Question 11

Describe the process for determining the total length of a solid rivet for a particular installation.

Answer 11

1.5 times the rivet diameter plus the grip length

Question 12

What two calculations must be made when bending sheet metal?

Answer 12

Setback and bend allowance

Setback (SB)—the distance the jaws of a brake must be
setback from the mold line to form a bend. In a 90° bend,
SB = R + T (radius of the bend plus thickness of the metal). The K-factor must be used for all bends that are smaller or larger than 90°. SB = K(R+T)

Bend allowance (BA)—refers to the curved section of
metal within the bend (the portion of metal that is curved in
bending).

Question 13

What factors must be considered to determine setback?

Answer 13

Bend radius and material thickness

The distance the jaws of a brake must be set back
from the mold line to form a bend. Setback for a 90° bend
is equal to the inside radius of the bend plus the thickness of the metal being bent. For a bend other than 90°, a K-factor must be used. See also K-factor.

SB=(R+T)K

Question 14

Name several facings and core materials used in bonded honeycomb structures intended for special applications

Answer 14

Stainless steel, titanium, magnesium, plywood, glass, nylon, cotton cloth

Question 15

What are the two primary uses for plywood in aircraft construction?

Answer 15

Gusset (reinforcing) plates, and aircraft skin

Question 16

Give three examples of plywood skin repairs

Answer 16

Splayed patches,

surface patches,

plug patches,

scarfed patches

Question 17

Is compression wood acceptable for structural repairs?

Answer 17

no

Question 18

What type of patch should be used to repair small holes in thin plywood skin if the skin is less than 1/10th inch thick?

Answer 18

A splayed patch may be used if the hole can be cleared out to a diameter of less than 15 thicknesses of the skin

Question 19

Describe the construction of a bonded honeycomb structure

Answer 19

It is a laminated structure that has a solid facing bonded to either side of a core made of open six sided cells.

Question 20

A drill bit used for drilling composites should have an included angle of how many degrees?

Answer 20

135

Question 21

What are the most common causes for delamination of a composite structure?

Answer 21

Sonic vibration,

expansion of internal moisture,

liquid leakage,

and a manufacturing error

Question 22

What type of defect in or damage to a bonded honeycomb structure can be repaired using the potted repair method?

Answer 22

Filling a hole

Question 23

What minimum curing temperature should be observed when joining wood with various adhesives?

Answer 23

70 degrees F or as specified by the manufacturer

Question 24

Why must the beveled cut be accurate on both pieces of wood with a scarf joint?

Answer 24

They must match exactly for a tight glue joint

Question 25

Where are splices to a wood spar prohibited?

Answer 25

Under an attachment fitting for the wing root,

landing gear,

engine mount, lift,

or inter plane strut

Question 26

What are the three types of glues used in modern aircraft construction and repair?

Answer 26

Resorcinol glue

phenol-formaldehyde glue

epoxy resin glue

Question 27

What is the max number of splices for a single spar?

Answer 27

2

Question 28

Describe the characteristics of a scarf joint

Answer 28

The pieces are tapered or beveled on a slope of 1 to 10 or 1 to 12