Analysis of Two Jet Engine Lubricating Oils and a Hydraulic Fluid: Their Pyrolytic Breakdown Products and Their Implication on Aircraft Air Quality

Aircraft air quality incidents are often traced to jet engine oil and/or hydraulic fluid leaking into bleed air used to ventilate the cabin. These contaminants can be subjected to temperatures in excess of 500°C. Exposed flight crew members have reported symptoms including dizziness, nausea, disorientation, blurred vision, and tingling in legs and arms.

Pyrolysis experiments of two jet engine oils and one hydraulic fluid at 525°C showed the engine oils to be important sources of carbon monoxide (CO). The same 5 out of the 10 possible tri-cresyl phosphate (TCP) isomers that were found in the bulk oils were found in the atmosphere at ambient temperatures after pyrolysis and were likely associated with smoke particles, illustrating an important potential route of exposure. Tri-orthocresyl phosphate (TOCP) was not found in the oils or fluid tested. The neurotoxin trimethyl propane phosphate (TMPP) was not found.

It was suggested that different symptoms could be expected depending on which fluid was pyrolized.