Narrative:

Fume event twice during flight. First when APU air connected on ground before push back- fume event was intense. Second-during descent with throttles at or near idle. On descent lasted 3-4 minutes. Dirty sock- moldy cheese smelli suffered physical consequences after these fume events. I had a severe headache later in the day of the occurrence. I experienced weakness and tremors in both arms and a feeling of anxiety for two days following the event. I could not get more than five hours of restless sleep for four days following this event. These are the same symptoms that I have experienced in previous fume events. Fume events of the nature described in my log write-up are typically caused by oil and/or hydraulic fluid leaking into the aircraft's air system; then becoming pyrolyzed when exposed to high temperatures. This process releases toxic substances into the aircraft ventilation system; exposing all persons onboard the aircraft. Tricresyl phosphate and tributyl phosphate are two known toxic chemicals released in this type of fume event. Both substances are neurotoxins. Fume events; an industry-wide problem; can result from design issues; broke or failing oil seals or maintenance irregularities such as over servicing oil or hydraulic systems. At [my company]; the typical maintenance action for curing a fume event write-up is changing the coalescer bags in the packs - which was the cure for this particular fume event. Coalescer bags can accumulate pyrolyzed oil residue but are not the root cause of the problem. Changing the coalescer bag only removes the smell temporarily and does not address the root cause of the issue. My company provides no training for maintenance personnel or pilots on recognizing; reporting; or proper maintenance action with regards to aircraft fume events. ICAO circular 344- an/202 provides guidelines on education; training and reporting practices for pilots and maintenance personnel in dealing with fume events. With regards to fume events; my company could greatly increase the safety margin for pilots by implementing recommendations of ICAO circular 344-an/202. I have accumulated a considerable amount of information and knowledge on fume events and have offered this knowledge to my company on a number of occasions. I continue to recommend that they take some action to address aircraft fume events due to the serious health and safety concerns these events can create.

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Original NASA ASRS Text

Title: Air carrier Captain reported two fume events during a flight. Maintenance changed the Coalescer bags; which the reporter believed dealt with the symptoms and not the cause.

Narrative: FUME EVENT TWICE DURING FLIGHT. FIRST WHEN APU AIR CONNECTED ON GROUND BEFORE PUSH BACK- FUME EVENT WAS INTENSE. SECOND-DURING DESCENT WITH THROTTLES AT OR NEAR IDLE. ON DESCENT LASTED 3-4 MINUTES. DIRTY SOCK- MOLDY CHEESE SMELLI suffered physical consequences after these fume events. I had a severe headache later in the day of the occurrence. I experienced weakness and tremors in both arms and a feeling of anxiety for two days following the event. I could not get more than five hours of restless sleep for four days following this event. These are the same symptoms that I have experienced in previous fume events. Fume events of the nature described in my Log write-up are typically caused by oil and/or hydraulic fluid leaking into the aircraft's air system; then becoming pyrolyzed when exposed to high temperatures. This process releases toxic substances into the aircraft ventilation system; exposing all persons onboard the aircraft. Tricresyl phosphate and tributyl phosphate are two known toxic chemicals released in this type of fume event. Both substances are neurotoxins. Fume events; an industry-wide problem; can result from design issues; broke or failing oil seals or maintenance irregularities such as over servicing oil or hydraulic systems. At [my company]; the typical maintenance action for curing a fume event write-up is changing the coalescer bags in the packs - which was the cure for this particular fume event. Coalescer bags can accumulate pyrolyzed oil residue but are not the root cause of the problem. Changing the coalescer bag only removes the smell temporarily and does not address the root cause of the issue. My company provides no training for maintenance personnel or pilots on recognizing; reporting; or proper maintenance action with regards to aircraft fume events. ICAO Circular 344- AN/202 provides guidelines on education; training and reporting practices for pilots and maintenance personnel in dealing with fume events. With regards to fume events; my company could greatly increase the safety margin for pilots by implementing recommendations of ICAO Circular 344-AN/202. I have accumulated a considerable amount of information and knowledge on fume events and have offered this knowledge to my company on a number of occasions. I continue to recommend that they take some action to address aircraft fume events due to the serious health and safety concerns these events can create.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.