Identification of Lubrication Oil in the Particulate Matter Emissions from Engine Exhaust of In-Service Commercial Aircraft

Abstract

Lubrication oil was identified in the organic particulate matter (PM) emissions of engine exhaust plumes from in-service commercial aircraft at Chicago Midway Airport (MDW) and O'Hare International Airport (ORD). This is the first field study focused on aircraft lubrication oil emissions, and all of the observed plumes described in this work were due to near-idle engine operations. The identification was carried out with an Aerodyne high-resolution time-of-flight aerosol mass spectrometer (HR-ToF AMS) via a collaborative laboratory and field investigation. A characteristic mass marker of lubrication oil, I(85)/I(71), the ratio of ion fragment intensity between m/z = 85 and 71, was used to distinguish lubrication oil from jet engine combustion products. This AMS marker was based on ion fragmentation patterns measured using electron impact ionization for two brands of widely used lubrication oil in a laboratory study. The AMS measurements of exhaust plumes from commercial aircraft in this airport field study reveal that lubrication oil is commonly present in organic PM emissions that are associated with emitted soot particles, unlike the purely oil droplets observed at the lubrication system vent. The characteristic oil marker, I(85)/I(71), was applied to quantitatively determine the contribution from lubrication oil in measured aircraft plumes, which ranges from 5% to 100%.

Composition and Sources of the Organic Particle Emissions from Aircraft Engines

“…One component of the organic PM exhaust we clearly identify as lubrication oil, a known component of aircraft engine PM emissions (Timko et al 2010b;Yu et al 2010Yu et al , 2012. Yu et al (2010) studied lubrication oil PM under well defined laboratory conditions and concluded that the mass spectra of pure synthetic lubrication oils could be differentiated from fuel-related hydrocarbons by strong signals at m/z 85 and 113 combined with weak signals for common ions derived from saturated and unsaturated hydrocarbons (i.e., delta series of 0 and +2 for unsaturated and saturated hydrocarbons, respectively; McLafferty and Tureček 1993).…”

Analysis of the effects of meteorology on aircraft exhaust dispersion and deposition using a Lagrangian particle model

“…Some aircraft operations within airports require engines to operate outside their optimal regimes, ranging from a maximum thrust during take-off to low power settings during ground operations. The non-ideal combustion conditions within engines may lead to the emission of by-products, including sulfur oxides, additional nitrogen oxides, unburned hydrocarbons, carbon monoxide and particulate soot (Dakhel et al, 2007;Timko et al, 2010;Yu et al, 2010Yu et al, , 2012Kinsey et al, 2011;Masiol and Harrison, 2014). These substances are emitted within the Planetary Boundary Layer (PBL) during the Landing TakeOff cycle (LTO) and can have plausibly local and direct effects on human health (Ratliff et al, 2009;Levy et al, 2012;Schlenker and Walker, 2012;Ashok et al, 2013;Yim et al, 2013).…”

Chemistry characterization of jet aircraft engine particulate matter by XPS: Results from APEX III

“…Timko et al reported significant organic content in PM sampled from idle conditions [26]. Recently both Timko et al [27] and Yu et al [9] found lubrication oil contribution to volatile PM. All such measurements were performed using the Aerodyne aerosol mass spectrometer.…”

“…Related work has found oil to contribute to secondary organics by overboard venting of the recirculation system through the engine nacelle [42] and also by fragmentation patterns of hydrocarbons of vented vapors within the core flow exhaust [9]. Yet fragmentation patterns, under exhaust flow conditions can be masked given the vast array of other organics produced by incomplete combustion.…”

“…nvPM chemistry also includes the carbon hybridization state, namely sp 2 versus sp 3 content [8]. Alkyl groups, as substituent groups on aromatic units and other hydrocarbon fragments from either fuel or oil can contribute to the latter [9]. Secondary condensation of volatiles can contribute to both.…”