FAA Airframe Oral

What is the function of a vortex generator

it is used to delay or prevent the separation of the boundary layer

What are the 3 axes of an airplane

longitudinal, lateral and vertical

What are the 3 primary flight controls of an aircraft

ailerons, rudder, elevator

Name several secondary flight controls and describe their general purpose

secondary flight controls consist of various types of trim tabs, such as balance tabs, anti-servo tabs, servo tabs and spring tabs. Their general purpose is to assist the pilot in moving the controls and to trim the aircraft for hands off flying

Name several types of auxiliary flight controls and describe their general purpose

The auxiliary flight controls consist of various high lift devices used during low speed flight such as leading and trailing edge flaps, slat, slots, speed brakes, etc.

What is a servo trim tabs

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

What is a spring tab

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

What is a balance trim tab

it is an auxiliary control designed to create aerodynamic forces to assist in moving a control surface. The tab is positioned by a control rod connected to a fixed surface on the same side as the horn of the tab

What are the 4 most common high lift devices

Leading and trailing edge flaps, slats and slots

Describe some of the tools used to check control surface travel

a universal propeller protractor or a special control surface protractor

Name 3 mechanical methods in which control surfaces may be actuated

cables, torque tubes and push pull rods

What is a fairlead

it is a device to prevent a cable from rubbing on aircraft structure

What are the most likely places for a control cable to wear or break

where a cable passes over a pulleys or through fairleads

What information is required before a cable rigging chart can be used

the ambient temperature and the cable size

What is the function of a cable tension regulator

it automatically adjusts to compensate for expansion and retraction in the aircraft structure

Describe the function of a rotorcraft collective pitch control

The collective pitch control causes each rotor blade to change its pitch angle by the same amount, thus increasing or decreasing the lift produced by the rotor

Describe the function of a rotorcraft cyclic pitch control

The cyclic control tilts the main rotor disk by changing the pitch angle of each rotor blade during its cycle of rotation which cause the helicopter to move in the direction the rotor disk tilts

What mechanism is commonly used to compensate for the torque produced by the main rotor of a helicopter

the tail or anti torque rotor

why should control surfaces be locked when an aircraft is parked

to prevent damage from the wind

How is the amount of thrust produced by the tail rotor controlled

by moving the foot pedals

What is the major type of damage to aluminum that is caused by exposure to the weather

corrosion

name several methods for forming sheet metal

bending or folding, stretching, shrinking, bumping, crimping

what are the dimensions of a properly formed rivet head

The head should be 1.5 times the shank diameter in width and .5 the shank diameter in height

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

A - plain

B - cross

D - raised dot

AD - a dimple

DD - double dash

What happens to the stem of a self plugging (friction lock) rivet when the rivet is installed

the stem is pulled until it snaps off and the remaining part is trimmed flush with the head

Name at least 3 types of self plugging mechanical lock rivets

CherryMAX, CherryLOCK, Olympic-LOK, HuckLok

What is the difference between the tools required to pull a CherryLOCK rivet and a CherryMAX rivet

CherryLOCK rivets require a tool for each different size and head shape, while 1 pulling tool will set any size CherryMAX rivet

Which of the 5 stresses is most likely to cause rivet failure

shear

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

for 5/32 inch or smaller diameter use the next larger size 2117 rivet, assuming the edge distance and spacing meet the minimum requirements

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

add the grip length (thickness of the materials being joined) plus 1.5 times the rivet diameter

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

not less than 2 rivet diameters from the edge and not less than 3 rivet diameters apart

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

by the thickness of the top sheet; thin sheets are dimpled, thick sheets may be drilled

What action is taken to prevent cracks from forming while dimpling magnesium or some hard metals

hot dimpling equipment is used to preheat and soften the metal before the metal before the dimple is formed

What type of damage can occur when using a rivet set that does not properly fit the rivet

If the radius of the set is too small, damage to the rivet head may occur; if the set is too big, it may cause damage to the sheet metal

Why is it important to use the proper size and weight bucking bar when performing sheet metal riveting

if the bucking bar is too large or heavy it may be difficult to control and may cause damage to surrounding structure, whereas is the bucking bar is too light, it will not properly upset the rivet before work hardening occurs

What procedures should be followed to properly remove a solid shank rivet

center punch the rivet, drill to the base of the head with the same size or 1 size smaller drill bit, use a pin punch to remove rivet head and drive the shank out of the hole while supporting the surrounding metal

What are the 2 special calculations that must be made when bending sheet metal

bend allowance and setback

What factors must be considered in order to determine setback

the thickness of the metal and the bend radius

what is done to a corner where 2 bends intersect to prevent cracking

relief holes are drilled at the corner

What are to reasons for installing a lightening hole in a sheet metal wing rib

reduce weight and increase stiffness

Describe a joggle and explain its function

a joggle is an offset formed at an intersection of 2 or more sheets of metal to allow the multiple sheets to be stacked flat against each other

When repairing an all metal aircraft, how do you determine what metals should be used

always use metal of the same type and thickness as the original structure

What are the 3 forms of wood commonly used in aircraft construction

solid ,laminated and plywood

What type of wood should be used when splicing or reinforcing plywood webs

the same type of plywood as originally used

Name at least 4 different types of defects found in wood

knots, checks, splits, pitch pockets, cross grain, curly grain, decay, dry rot, etc.

Can a section of wood containing a hard knot be used

yes within specified limits

what type of glue may have been used in older wooden aircraft construction that requires careful inspection to detect deterioration

casein glue

what are the 3 types of glues used in modern aircraft construction and repair

resorcinol glue, phenol-formaldehyde glue, epoxy resin glue

is compression wood acceptable for structural repairs

no

why should the various pieces of wood being joined be kept in the same room for at least 24 hours prior to joining

to allow the moisture content to equalize, thereby minimizing dimensional changes in the wood

Why is it important to consider the open assembly time when gluing wooden structures

if the maximum ope assembly time is exceeded, the joint may fail since the glue may begin setting up before the joint is assembled

why is it important to apply the proper clamping pressure to a glue joint

clamping forces air out of the joint, brings the wood together evenly and is, in part, responsible for the strength of the glue line

describe some of the methods used to apply pressure to glue joints

clamps, nailing strips, power presses, brads, nails and small screws

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

70 degrees F or as specified by the glue manufacturer

When inspecting wood structures, why might it be important to consider stains and discolored areas

stains and discoloration usually accompany decay and/or rot

Describe the acceptable methods used to repair elongated bolt holes found int he wooden wing spar

remove the section containing the elongated holes and splice in a new section or replace the entire spar

what type of joint is used to splice in a solid or rectangular wood spar

a scarf joint

in what areas are splices to a wood spar prohibited

under the attachment fitting for the wing root, landing gear, engine mount, lift or inter-plane strut

what is the maximum number of splices allowed for any single spar

2

describe the characteristics of a scarf joint

the pieces to be joined are tapered or beveled on a slope of 1 to 10 or 1 to 12

why must the beveled cut be accurate on both pieces of wood being repaired with a scarfed joint

the 2 pieces must match exactly to ensure a tight glue joint

what are the 2 primary uses for plywood in aircraft construction

gusset or reinforcing plates and aircraft skin

provide examples of at least 3 types of plywood skin repairs

splayed patches, surface patches plug patches and scarfed patches

what type of patch should be used to repair small holes in a thin plywood if the skin is less than .1 inch thick

a spayed patch may be used if the hole can be cleared out to a diameter of less than 15 times the thickness of the skin

What should be done to prevent a plywood patch and a pressure plate from sticking together if the glue is extruded from the joint

place a piece of waxed paper or vinyl plastic between the patch and the pressure plate

why are lightweight steel bushings sometimes used in wooden structures

bushings prevent the wood from being crushed as the bolts are tightened

what is the purpose of the large surface area washers when used on wooden structures

large washers provide additional bearing area for the hardware to help preclude damage to the wood when the hardware is tighted

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

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

Describe the construction of a bonded honeycomb structure

it is a laminated structure that has a solid facing bonded to either side of a core consisting of open 6-sided cells

what must be done with a damaged area in a bonded honeycomb structure prior to beginning repairs

the area must first be inspected to determine the damaged area prior to completely removing the damaged material

a drill bit used for drilling composites should operate at what speed

use of a air driven tool capable of a free speed of up to 20,000 RPM

what is the most common causes for delamination in a composite structure

sonic vibration, expansion of internal moisture, liquid leakage, and manufacturing error

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

filling a hole

name some of the factors that cause crazing in transparent plastic windows and windshields

exposure to ultraviolet light, stress, solvents and improper handling

how should a hole be drilled in Plexiglas to avoid damage to the hole when the drill breaks through to the underside

back up the plastic with a piece of wood and feed the drill slowly

What are the 3 principle types of welding

gas welding, electric arc welding and electric resistance welding

what are some of the advantages of gas shielded arc welding

the weld is stronger, more ductile, and more corrosion resistant

Which method of welding is least likely to cause buckling or warping of thin metal sheets

electric arc (TIG) welding

What is the purpose of shielding an arc with an inert gas

The gas prevents atmospheric oxygen and/or nitrogen from contaminating the weld

what is a common method of controlling expansion when welding a joint

place tack welds along the length of the joint

what is the effect of inadequate penetration on a weld

the weld will be weak

what is the purpose of the flux used with brazing and silver soldering

the flux cleans the base metal by removing any oxide film

what type of flame is used when torch brazing or silver soldering

neutral

what must be done to a soldering iron tip to increase the amount of heat transferred from the tip to the work

the tip must be clean of all contaminates and properly tinned

What is the preferred method of welding aluminum

TIG

what is the preferred method of welding magnesium

TIG

What precautions must be observed in order to weld titanium

all traces of oxygen and nitrogen must be kept away from the weld area

describe 1 type of repair that could be made to a dented steel tube cluster joint

a formed steel patch plate could be welded over the damaged area

how can a soft flame be obtained without reducing the heat output of the torch

use a larger tip and adjust the gas pressure accordingly

What factors determine the amount of heat delivered by a gas welding torch

the size of the tip and the gas pressure

when an oxyacetylene torch is extinguished, which valve is turned off first

acetylene gas

when a gas welding project is completed, what safety precautions should be accomplished

all valves turned off and gas pressures relieved

what should be done to a heat treated aluminum part after the welding repairs are completed

re-heat treat the part

welding magnesium can create a serious safety hazard. what is the nature of the hazard

magnesium burns with a very hot flame that is very difficult to extinguish

what technique might be used to enable a tight fitting inner sleeve to be inserted into a tubular repair

the inner tube could be chilled with dry ice or in a freezer while the outer tube is heated slightly with a torch

Aircraft covering fabrics are made of material from what 2 sources

organic and synthetic

how would you determine the strength requirements for fabric used to recover an aircraft

the fabric must at least be the quality and strength of the fabric used by the original manufacturer

What 2 types of organic fibers are used for covering aircraft

cotton and linen

what it meant by warp, weft and bias

warp is in the direction along the length of the fabric, weft is at right angles to the warp, bias is a direction at 45 degrees to the warp and weft

what is the purpose of the selvage edge of a roll of fabric

it prevents the fabric from unraveling