B-7b Aviation Maintenance: Workshop & Hand Tools

• Assessment paper for Aviation Australia, subject B-7b Maintenance Practices General
• Formative Assessment Paper 1, AA Form TO-21c
• There are 42 questions in total with 61 marks available. The question format is short answer.
• The time allocated is 60 minutes.
• Above 75% of the total mark will achieve a satisfactory result

Workshop Practices

• Three tool control goals:
  • Objective
  • Responsibility
  • Area control
  • Tool Identification
  • FOD critical zone-area
• Allowance: The difference between the nominal dimension and the upper and lower limit
• Before using a precision tool, ensure the tool's calibration has been done
• Two standards of workmanship:
  • Skill of worker; Quality of product; Attitude of worker
  • Duty of care to self, others, equipment

Common Hand Tools

• Caution for the safe operation of pounding tools (hammers): Never strike one hammer against the other as the hammers may shatter and may cause injury from flying particles; use the correct tool for the job; use clean, dry hands
• When selecting the correct hacksaw blade for the type of material, several teeth must be in contact with the work at all times
• Four safety precautions when operating hacksaws:
  • Eye protection
  • Support the work
  • Do not twist the blade
  • Correct blade for the job/correct tension
  • Reduce cutting force when the cut is almost through
  • Do not use excessive cutting speeds
  • Two or more teeth must be in contact at all times

Torque Wrenches and Torque Practices

• Torque is the term used to identify that the correct amount of force has been applied to a component
• Two types of torque wrenches:
  • Deflecting Beam/Dual indicator
  • Dial Indicator/Toggle or Break over
• The torque formula for fasteners where an extension increases the overall length: Ta= Tw (L+A)/L
• When torqueing a 5/8 inch self-locking nut, check and record the run-down torque of the nut, then add it to the final torque

Aircraft Maintenance Measuring Tools

• Imperial micrometer reading: 0.149 inches
• Imperial micrometer reading: .321 inches
• Imperial micrometer reading: .602 inches
• Three instances where dial indicators are used for checking components:
  • Out of round/ Bow/ Warp
  • End float/Backlash
  • Flatness/Run-out
  • Bolt stretch/Torque

General Purpose Power Tools

• When using a grinding wheel that shows signs of loading, glazing or grooving, the wheel must be dressed or trued for grooving
• Three safety precautions when operating a drill press:
  • Eye protection; do not hold with bare hands
  • Isolate power to the drill press when changing spindle speeds
  • Ensure clothing and long hair are secured and kept away from the drill.

Lubrication Equipment and Use

• The purpose of lubrication: to separate moving parts to reduce friction and minimize wear
• To lubricate an aircraft wheel bearing, pack the bearing with grease using a machine or by hand

Engineering Drawings, Diagrams & Standards

• Three types of working drawings:
  • Detailed
  • Assembly
  • Installation
• Schematic diagrams explain a principle of operation rather than to show the parts as they actually appear or their function on an aircraft
• The title block is located on an aircraft drawing in the lower right-hand corner
• ISO (International Standards Organization) standard that compliments a product or service: ISO 9002 which is a model for quality assurance in production and installation

Fits and Clearances

• Drills are classified into 3 groups of sizes:
  • Number form
  • Fractional form
  • Letter form
• Three bolt thread classes of fit (there are 5 classes of fit):
  • Class 1: loose fit
  • Class 2: free fit
  • Class 3: medium fit
  • Class 4: close fit
  • Class 5: tight fit
• Go/no-go gauge is the gauge that is used for repetitive tolerance inspections through production
• Dial test indicator is used to measure travel or end play

Springs

• The procedure for compression testing springs using a Spring Tester: the spring is compressed to a specific height, and the force required to do so is measured to ensure it is within tolerances
• A nick or scratch could create a 'stress raiser' potentially leading to spring breakage
• A condition that could lead to a spring losing its tension is overheating
• Apart from a nick or scratch, other defects that can lead to a spring breaking: corrosion or fatigue

Bearings

• Two cautionary procedures when handling cleaned oil/grease-free bearings:
  • At no time should the bearing be allowed to spin freely under spray or air blast, as spinning without lubricant can damage the bearing surface.
  • Oil-free bearings should only be handled using appropriate gloves to prevent fingerprint corrosion
• Long-term storage procedure for bearings: coat bearings in preservative, wrap in wax paper, and seal in heat-sealable plastic bags
• Brinelling is the bearing defect indicated by marks on the races at the same spacing as the balls or rollers
• Galling is the bearing defect that results in metal transfer from the rolling elements to the races

Transmissions

• The defect indicated on the pulley is that it is worn
• Chain tension measured by deflecting the chain under a given load
• Two defects to inspect for when inspecting control rods:
  • Corrosion/ scratches/ dents
  • Chafing/ buckling/ bends, bearing wear
• Interference wear: Wear caused by misalignment of gears

Control Cables

• Aircraft cables are preformed so if the cable is cut, the wire will not spring out
• The strength of a hand-woven splice cable termination is 75%
• Prior to inserting the cable into a fitting before swaging, the cable must be kinked so it will not slide out of the terminal