Module 7.1 Safety Precautions in Aircraft Maintenance

Lockout-Tagout (LOTO)

The procedure of de-energising a system, locking the power switch or circuit breaker in the off position, and applying a visible tag to prevent accidental re-energisation during maintenance.

Standard AC electrical power supply specifications on most aircraft

$115\,V$ at $400\,Hz$

Pressure of compressed air typically supplied in aircraft maintenance workshops

Approximately $80\,psi$

Safety reason why standard tools must not be used on aircraft oxygen systems

Standard tools can cause sparks or carry oil and grease residues, which can trigger spontaneous combustion or explosion in oxygen-enriched environments.

Perfluorinated Polyether (PFPE) lubricants

Approved oil-free lubricants (such as Fomblin®) suitable for lubricating gauges or tooling used on oxygen systems.

Primary hazard associated with inert gas such as nitrogen

Asphyxiation caused by displacing breathable oxygen in confined or inadequately ventilated areas.

Function of On-Board Inert Gas Generating Systems (OBIGGS)

Supplying a continuous flow of nitrogen-enriched gas to aircraft fuel tanks to eliminate combustible fuel-air mixtures.

Minimum required separation distance between stored oxygen cylinders and fuel-gas cylinders

At least $3\,m$

Globally Harmonised System (GHS)

An international UN framework standardising chemical hazard classification, 16-section Safety Data Sheets (SDS), and warning symbols.

Control of Substances Hazardous to Health (COSHH)

UK regulatory framework requiring employers to identify, assess, and control health risks from hazardous workplace chemicals.