Hazards of Airplane Fuel-Tank Entry A large percentage of the work involved in properly inspecting and modifying airplane fuel tanks and their associated systems must be done in the interior of the tanks. Performing the necessary tasks requires inspection and maintenance personnel to physically enter the tank, where many environmental hazards exist. These potential hazards include fire and explosion, toxic and irritating chemicals, oxygen deficiency, and the confined nature of the fuel tank itself. In …showed first 75 words of 2647 total…

…showed last 75 words of 2647 total…cause increasingly severe reactions. PERMISSIBLE EXPOSURE LIMIT (PEL) The maximum concentration of an airborne chemical that a person may be exposed to over an eight-hour work shift. Usually expressed as a time-weighted average. UPPER EXPLOSIVE LIMIT (UEL) Same as upper flammability limit. UPPER FLAMMABILITY LIMIT (UFL) The maximum concentration of a fuel vapor in air that will support combustion, usually expressed as a percentage. Fuel-vapor concentrations above the UFL are considered too rich to burn.