Tag Archives: exposure

Root Cause Analysis - Incident Investigation

Toxic Fumes on Aircraft

By ThinkReliability Staff

A settlement against an aircraft manufacturer, with regards to a claim that faulty design allowed toxic fumes to enter the cabin, occurred in early October 2011.  It is the first of its kind to occur in the U.S., but may not be the last.  A documentary entitled “Angel Without Wings” is attempting to bring more attention to the issue, which air safety advocates claim has affected the health and job-readiness of some airline crewmembers.

Although the aircraft manufacturing and operating industries maintain that the air in cabins is safe, breaches are rare, and that the small amount of toxicity that may get into the cabin is not enough to affect human health, the issue is expected to gain more attention, as some industry officials maintain that approximately one flight a day involves leakage of toxic fumes into the passenger cabin of an aircraft.  Although there is debate about the amount of fumes required to cause various health effects, allowing toxic fumes of any amount into a passenger cabin is an impact to both the safety and environment goal.  Additionally, the lawsuit – and the potential of more to come – against the manufacturer is an impact to the customer service goal.  Although the suits have been brought by crew members, there is also a concern for the safety of passengers with respect to exposure to the contaminated air.

The toxic smoke and fumes enter the plane’s air conditioning system when engine air gets into the bleed-air system, which directs air bled from engine compressors into the cabin.  Because there is currently no effective way for crew members to determine that the air is contaminated – no detectors and insufficient training for these crew members to recognize the source and possible outcome of the fumes – the air continues to be fed to the cabin. The creators of the documentary, and other air safety advocates, are requesting that better filters be installed to prevent the toxic fumes to enter the cabin, less toxic oil be used so that the fumes from any leaking oil are less damaging to human health, that detectors be installed in air ducts to notify crew of potential toxicity in the air supply, and better education and training to help crew members identify the potential for exposure to toxic fumes.  However, the manufacturer’s newest design makes all this unnecessary by using an aircraft design that provides air from electric compressors.  Given the length of time that aircraft remain in the air, it will be decades before the system may be phased out.  In the meantime, advocates hope that other corrective actions will be implemented to decrease the potential of exposure to passengers and crew.

To view the Outline and Cause Map, please click “Download PDF” above.  Or click here to read more.

Root Cause Analysis - Incident Investigation

Tragedy in Bhopal

By ThinkReliability Staff

While researching the tragedy in Bhopal, India, I discovered that there are two theories about what occurred on December 3, 1984 that resulted in a tremendous loss of life. One theory is from a report done by an Engineering Consulting firm hired by Union Carbide (the company that owned the plant in question) that determines that the release was caused by sabotage. Theory #2 is that a combination of inexperienced, ineffective workers and a badly maintained plant with inadequate safety standards that was being ready for dismantling experienced a horribly catastrophic chain of events that ensured that anything that could go wrong, did. For completeness, I have included both in my final Cause Map (which you can see by clicking “Download PDF” above). But for now, I’d just like to focus on the second.

In the wee morning hours of December 3, 1984, over 40 tons (this amount is also debated, but 40 tons appears to be the most popular, purely based on number of references that mention it) of methyl isocyanate (MIC) were released over the community of Bhopal, India, with a population of 900,000. Partially because of the transient nature of the population, and partially due to the general obfuscation of data from all sources involved, the number killed ranges from 2,000 to 15,000. The 2003 annual report of the Madhya Pradesh Gas Relief and Rehabilitation Department stated that a total of 15,248 people had died as a result of the gas leak. Based on claims accepted by the Indian government, there were at least 500,000 injured. This led to what has been called “The World’s Largest Lawsuit”, which I assume refers to the number of people represented, and certainly not the monetary amount of the settlement, which is a paltry $470 million. After the accident, the plant, after a series of legal maneuvers, was abandoned. Extensive cleanup was required, and still has not been completed. The impact to the goals are shown in the outline on the downloadable PDF.

The deaths and environmental impact were caused by the release of over 40 tons of methyl isocyanate (from here on out, we’ll refer to it as MIC). The release occurred when a large volume of MIC was put through an ineffective protection system. The release lasted several hours, because workers were unable to stop it, and because of an ineffective warning system. The release occurred when a disk and valve that led to the protection system burst due to an increase in pressure. The increase in pressure was caused by an increase in temperature resulting from a reaction between MIC and water when the refrigeration system was shut down. There were 41 metric tons of MIC in the tank, stored for use in the plant. How the water was introduced is the debate in the two theories I mentioned above. But regardless, water got in to the tank, either by sabotage or by leaking through a vent line. We will probably never know exactly what happened. But we do know that ineffective safety systems can result in a massive loss of life, as happened here.