UK CAA Part-66 Module 7: Maintenance Practices Review

Comprehensive vocabulary flashcards covering maintenance practices, safety, tooling, and regulatory procedures for UK CAA Part-66 Module 7.

Safety Hierarchy

The prioritized order of hazard management starting with elimination, followed by removal, guarding, personal protection, and finally safety education.

HASAWA (1974)

The primary legislation in Great Britain governing occupational health and safety, placing duties on employers, employees, and the self-employed.

ACOP (Approved Code of Practice)

A publication with special legal status providing practical guidance on regulatory compliance; failure to follow it requires proof of an alternative safe method.

Written Health and Safety Policy

A legal requirement for any UK organization employing $5$ or more people.

MSDS Update Interval

The frequency at which Material Safety Data Sheets must be refreshed, typically every $3$ years unless significant hazard data changes earlier.

Oxygen System Lubrication

A strictly prohibited practice using standard oils or greases, as these can spontaneously combust when in contact with concentrated oxygen.

Lower Explosive Limit (LEL)

The minimum concentration of fuel vapour in the air required to support an explosion; fuel tank atmospheres must be kept well below this.

Class B Fire

A fire classification involving flammable liquids such as petrol, oils, or lubricants (POL).

Halon 1211 (BCF)

A streaming extinguishing agent used specifically in portable units, distinct from the total flooding agent Halon 1301 used in fixed systems.

Calibration Label Criteria

The three mandatory items required on a precision tool's tag: the date of the previous test, the next due date, and an authorized signature or stamp.

Allowance

The intentional minimum clearance designed between two mating parts at their maximum material limits.

Tolerance

The total permissible variation in a single dimension of one specific part.

Torque Wrench Working Range (Mechanical)

The effective operational span of a non-electronic torque tool, typically defined as $20\%\text{--}80\%$ of its full scale.

Torque Wrench Working Range (Electronic)

The high-precision operational span of a digital torque tool, typically ranging from $10\%\text{--}100\%$ of its full scale.

Standard Drill Point Angle

The general-purpose angle of $118^{\circ}$ used for materials like mild steel or aluminium, compared to $135^{\circ}$ for harder materials.

Reamer Operation Rule

The requirement to never rotate a reamer backwards and to continue forward rotation while withdrawing it to prevent scoring the hole.

PMMC Sensitivity

The reciprocal of a meter's full-scale current, representing the total resistance per volt required for full deflection.

BITE Limitation

The inherent weakness of internal test equipment where it cannot accurately perform self-tests on its own functioning.

Third Angle Projection

The standard American/UK drawing orientation where each view shows the side of the object immediately adjacent to the viewing plane.

ATA Chapter 08

The standardized section in technical manuals dedicated to aircraft Levelling and Weighing.

Shrink Fit

An interference fit achieved by thermally expanding the outer member or contracting the inner shaft to join parts permanently.

Maximum Shaft Bow

The general structural limit for straightness over the length of a member, usually restricted to $1$ in $600$.

EWIS Test Sequence

The mandatory chronological order for electrical wiring checks: Visual, then Bonding, then Continuity, and finally Insulation.

Class L Bond

An electrical connection designed for lightning protection, requiring a resistance of less than $0.05\,\Omega$.

Kelvin (Four-Wire) Method

A testing technique for extremely low resistances where one pair of leads carries current and another measures voltage drop to eliminate lead resistance errors.

Standard Wire Bend Radius

The minimum curvature for wire bundles, generally set at $10$ times the outside diameter of the largest cable.

Front Release Connector

A connector type where pins are extracted by pushing from the mating face side towards the rear.

Rivet Pitch

The center-to-center distance between fasteners in a single row, typically equivalent to $4 \times D$ (diameter).

Smoking Rivet

A visual indication of fretting corrosion appearing as a dark, greasy residue around a rivet head, caused by minute relative movement.

Pipe Flattening Limit

The permissible degree of deformation in a bend, where the small diameter must not be less than $75\%$ of the original outside diameter.

Standard Flare Angle

The uniform angle of $37^{\circ}$ used for aircraft flared pipe fittings.

True Brinelling

Damage characterized by regularly spaced indentations in a bearing raceway caused by excessive impact or static overloading beyond elastic limits.

False Brinelling

Wear and corrosion hollows in a bearing that resemble impact dents but are actually caused by vibration while the bearing is stationary.

Chain Elongation Limit

The maximum permissible stretch under specified tension, typically ranging from $1.5\%\text{--}3\%$, with replacement mandatory at $5\%\,\text{wear}$.

Teleflex System

A mechanical control system capable of transmitting both push and pull forces, eliminating the need for return springs.

Neutral Axis (Sheet Metal)

The imaginary line in a bend that remains unstretched and uncompressed, located approximately $0.445 \times \text{Material Thickness}$ from the inside radius.

Warp Clock

A diagrammatic tool used to identify and align the high-strength longitudinal fibers of composite fabrics during repair.

Prepreg Storage

The requirement to keep composite materials in a freezer below $-18\,^{\circ}\text{C}$ ($0\,^{\circ}\text{F}$) to prevent premature curing.

60/40 Solder

High-tin-content solder ($60\%\,\text{tin}, 40\%\,\text{lead}$) used for electronic components to ensure high tensile and shear strength.

Neutral Flame

A balanced oxy-acetylene gas mix burning at approximately $3300\,^{\circ}\text{C}$ that does not alter the base metal's composition.

LEMAC / TEMAC

References for the Leading Edge and Trailing Edge of the Mean Aerodynamic Chord, used to define center of gravity positions.

Transit Check

A routine pre-flight inspection performed on the ramp before every sector to check for leaks, damage, and security.

MEL Category B

A Minimum Equipment List rectification interval requiring repair within $3$ consecutive calendar days, excluding the day of discovery.

Dye Penetrant Limitation

An NDI constraint where defects must be open to the surface to allow the liquid to enter for detection.

HIRF

High Intensity Radiated Fields; electromagnetic radiation from radio or radar that can induce unwanted currents in aircraft systems.