Caravan 208A
Flight Crew Air Transport Pilot (ATP); Flight Crew Flight Instructor; Flight Crew Instrument; Flight Crew Multiengine; Maintenance Airframe; Maintenance Powerplant
Flight Crew Last 90 Days 250; Flight Crew Total 8000; Flight Crew Type 4400
Physiological - Other
Aircraft Equipment Problem Critical; Flight Deck / Cabin / Aircraft Event Smoke / Fire / Fumes / Odor; Flight Deck / Cabin / Aircraft Event Illness / Injury
General Physical Injury / Incapacitation
Aircraft; Equipment / Tooling
I am a commercial pilot currently flying a turboprop; single-engine airplane. The Company is in the process of upgrading our aircraft to advanced; glass-cockpit technology and TKS. At this point in my Company's experience with the TKS system; with some limitations; it appears to be effective in preventing excessive ice accumulations on our aircraft. As the TKS system is installed on the aircraft that I fly; with the system operating; a prop slinger throws fluid over and off of the prop in flight. As designed; the excess fluid travels back over the engine cowling and windshield. From personal experience I can tell you that fluid vapors and occasionally raw TKS fluid spray is sucked into the cockpit (a low pressure area) with the system in use when there is even the slightest windshield and/or cabin air leak in the aircraft. In addition with the TKS system in operation; fluid from the prop slinger also finds its way into the engine compartment (a low pressure area) where it collects in the heating system fresh air box. Fluid contaminated air from the air box and; occasionally; fluid mist is then pushed into the cockpit via engine compressor bleed air through the heating system when it is in use. Fluid vapors and/or mist may also enter the cockpit via the TKS fluid that flows along the outside of the engine cowling and along the intake air; is sucked into the engine compressor that provides bleed air to the cockpit heating system. Fumes in the cockpit while the TKS and heating systems are in use at that same have been reported by at least 6 out of 10 pilots at my base and by company pilots flying from other bases. Some pilots; myself included; who have reported smelling TKS fumes in the cockpit; have also experienced physical sensitivities to the fumes. I personally have experienced throat irritation resulting in constant coughing; a deep burning sensation in my chest and a throbbing headache from breathing the fumes during 6 flights over a 3 day period. During these flights; the TKS and heating systems were used together for as little as 15-20 minutes duration. In each case turning off the cockpit heat while operating the TKS system eliminated the fluid smell and allowed me to recover from the symptoms in a short time. Since reporting my experiences to my company; I have been assigned a non-TKS airplane for my flights while the problem is being investigated and a resolution implemented. This decision by the Company preludes my having to fly while wearing an O2 mask or without cabin heat. While my situation regarding the TKS cockpit fumes issue is for now resolved; I continue to feel great concern for the other pilots flying my type of aircraft; who; while not experiencing physical symptoms; are breathing toxic vapors entering the cockpits of our planes. The MSDS for the TKS fluid that my company uses (spec 406B) lists a composition of 85% mono ethylene glycol (ethane; 1;2-diol); 5% ethyl alcohol (ethanol) and 10% water. The hazards of exposure to both mono ethylene glycol and ethyl alcohol are well documented and have been widely reported. The barrels of the TKS 406B fluid are clearly marked with labels warning of the fluid's toxicity and cautioning against inhaling vapors and/or mist during handling. The MSDS for the fluid also lists 'symptoms of intoxication' as a result of a prolonged inhalation. How long is 'prolonged inhalation' in the absence of physical symptoms? What effect does vapor inhalation have on the thought process; judgment; reaction times; etc.; of a pilot flying a single-engine airplane alone in IMC and icing and possibly at night to a low minimum approach and landing? Could this not be a situation similar to a pilot who unknowingly is breathing carbon monoxide while flying? Another question is; when the TKS system is being tested and certified by the aircraft manufacturers and the FAA for use on small; single-engine; non-pressurized cockpit aircraft; tests were conducted to verify that fluid fumesand/or mists would not enter the cockpits of equipped aircraft through the cabin heating system in operation? In view of my personal experience and that of the other pilots who have noted TKS fluid fumes in the cockpits of other aircraft; if the answer to my question is that tests for fumes were done; how is it that their presence in the cockpit was not discovered? If the answer to my question is that tests were not done; then I ask the question; 'why not?' and 'when will it be done?' TKS technology has been and is increasingly being marketed to the owners and operators of a variety of small; non-pressurized cockpit aircraft (Kodiak; Cirrus and Cessna 208/210/206/182; Bonanza; Pipers; etc.) that use heated air from sources located in engine compartments for cabin heat. Using my company's experience with TKS as a baseline and given the aviation industry's efforts to expand the use of TKS technology; I believe that the potential exists for many more pilots to be unknowingly exposed to toxic fumes from the TKS fluid that their anti-ice systems use while operating in icing conditions. As a concerned aviation professional I urge the aircraft industry and the FAA to investigate the presence of TKS fluid fumes in the cockpits of equipped aircraft and to enact a resolution to this potentially catastrophic hazard to aviation safety as soon as possible.
The Reporter had extensive systems knowledge and explained the path prop slinger anti-ice fluid follows for entry to the cockpit. The fluid enters the engine intake as it flows over the cowling toward the cockpit windows. After entering the engine intake airflow; the fluid and vapor flows around the Inertial Separator into the engine compressor section. Compressor bleed air; at about 500 degrees; is then off and sent to the Mixer/Muffler where it is cooled by ambient air which is extracted in the lower cowling area. The ambient air is collected in a low pressure area and contains anti-ice fluid and vapors which are again mixed with vaporized anti-ice fluid extracted from the engine compressor.The Reporter stated that the initial smell is alcohol which dissipates as the olfactory sense quickly becomes saturated by it within five minutes. Over a period of forty-five minutes to an hour; the Reporter develops a dry cough; and then a sore throat; a head ache; then becomes light headed. He has learned that by using his oxygen mask early on he can mitigate the anti-ice fluid component's effects. The Reporter believes that any unpressurized aircraft with the prop slinger anti-ice type system will experience similar effects. In his case; because he flies five days a week and is exposed to the fluids effects during winter months for hours at a time on a daily basis; the short and long term effects will be more pronounced than a general aviation pilot flying 100 to 200 per year and very infrequently in icing conditions. The Reporter stated that not all of his company's pilots experience the fluid's effects as acutely as he does. Two pilots in particular have been questioned about their apparent behavior after flights with prolonged exposure. This pilot reported hypoxic to mildly intoxicated behavior; but definitely signs of cognitive impairment.
A C208 pilot reported cabin contamination as TKS propeller anti-ice fluid enters the cockpit as a vapor in the nearly 500 degree engine compressor bleed air used for heating which is cooled by ambient air also exposed to the anti-ice fluid entering the lower cowling.