Caravan 208A
Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument
Distraction; Situational Awareness; Confusion
Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Other / Unknown; Flight Deck / Cabin / Aircraft Event Smoke / Fire / Fumes / Odor; Flight Deck / Cabin / Aircraft Event Illness / Injury; Inflight Event / Encounter Weather / Turbulence
Flight Crew Took Evasive Action
Human Factors; Weather; Aircraft
I ran the TKS system for no more than 10 minutes in HI mode; using the windshield spray bar twice in during the first 20 min of the 1.6-hour two-leg flight. Shortly after activating the TKS system and using the spray bar; I detected a strong alcohol odor in the cockpit that irritated my nose and throat. The cabin heat/defroster was NOT in use at this time and the mixing valve was closed. From past experience I recognized that my aircraft had a windshield air leak that was allowing air stream TKS fluid mist and fumes to enter the cockpit. Due to my being on an instrument approach and still in icing I was unable to don my personal O2 mask resolving to turn off the TKS system as soon as I was out of the ice. The rest of the leg and landing were without incident although my throat and nose continued to feel irritated during my time on the ground prior to launching on the second leg. Approximately 10 min after departing in level flight with neither the TKS system nor the cabin heat/defroster in use I realized that my nose and throat were still irritated and that I still smelled the alcohol smell so I donned my personal mask and began breathing 100% O2. From past experience with this scenario I knew that if I did not do this promptly a headache and dizziness would follow. Immediately upon commencing breathing O2 I felt less irritation in my nose and throat so I wore my mask for the remaining 50 min of the flight through the approach and landing without incident and without further nose/throat irritation or headache. Upon landing I wrote up the probable windshield air leak and alcohol odor in the cockpit. From past experience I have observed that TKS fluid mist and fumes can enter a cockpit through a windshield air leak as residual TKS fluid present in the system lines from moderate use; even when the system is no longer in use; drains down to the prop slinger and is sprayed into the air stream surrounding the engine nacelle and cockpit. Also from past personal experience I have observed that breathing O2 is the only effective way of mitigating the nose/throat irritation and avoiding headache/dizziness that results from breathing the TKS fluid vapors for any length of time.
A C-208 Captain reported physical symptoms following TKS anti-ice spray bar fluid dispensing. A windshield air leak suspected.