Preliminary Analysis of Engine Bleed Air Oil Contamination with the Aerotracer® during Off-Wing Acceptance Testing and On-Wing Flights

Statistics affirm that the number of fume events per 1000 flights increased from 0.0027 in 2008 to 0.09 in 2011. Concerns have been raising about the possible link between these fume events caused by bleed air contamination with engine oil and chronic illness cases among flight crew. Engine oil is a mixture of chemicals, including Tricresyl Phosphate, an antiwear additive. An attempt to characterize bleed air contamination frequency was performed using a gas analyser, the Aerotracer®. This equipment was first tested with different oil samples to verify the influence of temperature and degradation levels in the process of detection. The Aerotracer® was then used at the test cell, with the intention of verifying the existence of bleed air contamination with oil and thus help in troubleshooting procedures as well as the prevention of future fume events. For this purpose, a pipe structure was built from the engine to the test cell control room, for a continuous removal of bleed air and subsequent analysis with the Aerotracer®. The system was tested and is fully operational for the engine power settings: Take-off, Max continuous and Approach Idle. The Aerotracer® was also used during flights to analyse the air quality inside the cockpit. A total of 104 flights and 9 different aircrafts were investigated, which corresponds to 60360 minutes of measurements. Lastly, different engine oil samples were analysed with SPME-GC/TOFMS, to study the presence of organophosphates and aromatic amines. Tricresyl phosphate isomers were found in all the samples with the exception of oil C, nevertheless none of the TCP toxic isomers were found