Caravan Undifferentiated
Flight Crew Air Transport Pilot (ATP)
Physiological - Other
Flight Deck / Cabin / Aircraft Event Illness / Injury
[While] enroute I encountered icing conditions that required the operation of the TKS system in both HI and NORMAL modes for approximately 30 minutes. Upon turning the TKS system ON with the cabin heat/defroster system also ON; I immediately detected the smell of alcohol. In response and to avoid experiencing the negative effects of breathing the TKS fluid fumes I turned the cabin heat/defroster OFF; donned my personal O2 mask and began breathing O2. I then turned ON the cabin heat/defrost system once again and continued to breathe O2 even after I had exited icing conditions and was able to turn the TKS system OFF. The cabin heat/defrost system was used for most of the remainder of the flight with an occasional odor of alcohol noted while I was communicating with ATC and I needed to move my boom mic into position under my mask.Additionally; on two other occasions in the past week I experienced throat irritation; cough; chest discomfort and light-headedness that required my use of O2 while in flight after having operated the TKS system in HI mode for less than 10 minutes in icing conditions. On both occasions I detected the telltale alcohol smell upon turning the TKS system ON; but due high workload during the short flight leg (descent and approach) I was not able to don my personal O2 mask as I routinely do whenever I operate the TKS system and the heater/defroster at the same time in flight. In both cases I continued running the TKS system in HI mode and switched the heater/defroster OFF; that eliminated the alcohol odor immediately; for the remainder of the flight leg. Also; on both occasions at approximately 10 minutes into the subsequent flight leg; while maintaining VFR conditions with the heater/defroster ON; but with the TKS system OFF; I began to feel the above-mentioned symptoms; also detailed in the MSDS for the TKS fluid. In both cases donning my O2 mask and breathing 100% O2 for the remainder of the flight (45min) relieved my symptoms. As my aircraft's windshield had been recently re-sealed and I had not detected any air leaks while flying; based on past experience; I attribute the fumes entering the cockpit to the in-flight drain-down of residual fluid when the system is turned OFF entering the cabin bleed air system via intake air to the engine compressor.Having flown a TKS-equipped Caravan for more than 2 years while regularly operating the system in icing conditions; performing pre-flight ground testing/post-flight purging of the system and servicing of the fluid tank in the course of my normal 5 day flight-duty weeks during our region's 6-8 month icing season I have observed that I appear to have become much more sensitive to the smell of the of the fluid and the presence of fumes in the cockpit. To avoid experiencing the negative effects of breathing the TKS fluid fumes I now need to don my O2 mask sooner and wear it longer during flight while the TKS system is in use; with or without cabin heat/defrost. In addition; other affected pilots from within my airline have reported the same apparent increased sensitivity to the fluid and fumes. I have also observed that breathing the TKS fumes from fluid puddled on the ramp during/after ground test/panel purge causes me to feel throat irritation and have an involuntary 'dry cough'. To counter this; for the past two years and continuing into the future; I have conducted all of my cold WX pre-flights and walk-arounds while wearing a paint vapor face mask that blocks the smell of the fluid and relieves my symptoms. From conversations that I have had with pilots of TKS-equipped Caravans within as well as outside of my airline I know that I am not alone in this practice.From my research into the TKS system and fluid I have found that data does not exist with regard to the mid to long-term effects of regular and repeated exposure to significant concentrations of the fumes; mist and/or droplets of the fluid's active ingredients; ethylene glycol and ethanol. Allthat does exist are short-term studies of airport aircraft de-icing workers. Industry and the CDC/NIOSH does have much to say about the toxicity and hazards of both of the chemical components of the TKS fluid with the CDC Emergency Response Guide stating; 'Exposure to levels of ethylene glycol concentrations higher than 80 ppm results in intolerable respiratory discomfort and cough'. That concentration is significant given that it is much higher than the levels that have been randomly measured in our cockpits to date yet these very symptoms are routinely experienced by pilots of TKS-equipped Caravans. Many pilots flying these aircraft have shared that they are fearful for their health and safety while flying in icing conditions with the system operating; but are reluctant to seek medical attention when suffering the after-effects of exposure to the chemical components of the fluid. Pilots have voiced their fears about even admitting to medical personnel that they had been exposed to toxic fumes and/or that they could develop an illness or impairment that could cause them to lose their medical certificates and their livelihoods. As a result of these fears it is my belief that the cockpit fumes issue has been under-reported throughout the TKS-equipped Caravan fleet until recently. It is also a fact that pilots have left my airline to avoid having to fly these aircraft in their present configuration. In my opinion and from personal experience with the system this issue will continue to be a health and safety hazard to all pilots of TKS-equipped Caravans flying in icing conditions; whether symptomatic or not (see the Material Safety Data Sheet (MSDS)). I also feel that regardless of whether TKS fluid mist and fumes enter the cockpit via the cabin heat/defrost system; through a windshield air leak or through closed; but poorly-sealing fuselage and wing fresh air vents pilot health and safety will continue to be compromised unless a fundamental change to the configuration of the TKS system that removes the presence of the TKS fluid from ahead of the cockpit is affected and some form of a hybrid thermal/fluid system is adopted.
A reporter advises he has resorted to devices such as a personal O2 supply and mask to combat debilitating ENT [Ear-Nose-Throat] effects of TKS fluids ingested in the AC systems of his company's C208 fleet. He also utilizes a spray painting vapor mask to combat the fluids vapors during walk-arounds.