2014
Volume 14, Number 4, ppp. 90–93
Routine mechanical causes of aircraft air supply contamination
G.A. Davidson
Consulting aero-engineer, 6 Arran Court, Kirk St, Strathaven, Lanarkshire, Scotland
The sources of air supply contamination are reviewed. They include the sometimes heavily contaminated air at ground level at an aerodrome that is inevitably drawn in to the air supply system. Volatile contaminants carried in the cargo hold of an aircraft can also find their way into the cockpit and passenger cabin. During a flight, throttle changes can exacerbate oil seal leakage and automatic control of the throttle is likely to force almost continuous changes in the loading imposed on seal configurations. Contamination from some of these sources could be significantly reduced by relatively simple changes in operating procedures.
Keywords: bleed air auto throttle, auxiliary power unit, exhaust gases, ground power unit, hold contamination