Narrative:

We diverted approximately 500 miles north northeast of our planned destination. The initial plan was to land; refuel; and then continue on to the filed destination when the weather lifted permitting us to land. That did not happen. We landed with approximately 9;500 pounds of fuel left on the aircraft; total flight time 10:18. The entire flight had been nominal and uneventful until being diverted and subsequently starting the APU on taxi in. We started the APU; and we taxied to a spot on the taxiway where controllers had asked us to park behind one other aircraft. Once the brakes were set; I proceeded with engine shut down. The APU had been started and was running approximately 4-5 minutes but once engine shut down occurred it began supplying bleed air to the packs; the entire cabin filled with a very dense and opaque acrid white smoke. The burnt chemical aroma of the smoke being pumped into the cabin was noxious. The moment I recognized that smoke was entering the cabin I immediately had the APU bleed air turned off from the packs and the smoke stopped pouring into the cabin. A few moments later the APU experienced an 'automatic shutdown' due to low oil and low pressure leaving the aircraft powerless; no conditioned cabin air; and with a cabin filled with toxic opaque smoke on an active taxiway only battery power available. The smoke became so dense in the cabin (and dark from lowered window shades) that our lead flight attendant asked permission to instruct the flight attendants to open all cabin doors immediately to evacuate the smoke and ventilate the cabin. I agreed. Once the doors were opened the cabin smoke cleared within 5 minutes. There was a residual 'chemical' odor that lingered throughout the cabin even without conditioned air or power. The temperature in the cabin began to climb dramatically once we lost conditioned air from the packs. Just a few minutes after experiencing the APU auto shutdown; we noticed airport fire-rescue trucks heading to our aircraft rather rapidly with lights and sirens. We were later informed by ground personnel that they responded as a result of the smoke emanating from the tail of the aircraft (the APU compartment); and the opened cabin doors. The fire-rescue team witnessed this from across the field; without the flight crew requesting assistance. Passengers plus crew were now trapped on an aircraft without conditioned air; power; or working lavatories. The 31C OAT was now making the cabin a toxic sweat lodge. The cabin temperature climbed to 36C or 97F even with the doors open. That is when things with the passengers began to spiral out of control. After over two hours of sitting on a trashed toxic and powerless aircraft; people were becoming physically ill and vomiting; the passengers that weren't sick due to the toxic fumes were now affected by the stifling temperature onboard the aircraft and became more agitated the longer we sat parked. As the situation declined to anarchy; our lead flight attendant informed me simply 'that if ground crew did not initiate a tow to the gate; he was going to initiate an emergency evacuation right there on the taxiway.' I have no doubt we would probably still be sitting there had we not threatened ground with an emergency evacuation. We were towed to a gate which only took 12 minutes.we secured the aircraft and we entered a logbook entry regarding the APU failure and toxic air event. The entire crew was escorted through customs and transported to the hotel for ron. The APU during start up ruptured and blew out all of its oil; allowing it to seep into the air conditioning packs. APU operated normally prior to our departure the night before with no indication of the impending failure. Alternates in this region are meaningless because the ATC authorities are in command of where you can go if an airport is unavailable for landing.

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Original NASA ASRS Text

Title: After diverting for below minimum destination weather to an unscheduled alternate; a B767-200's APU oil system failed and filled the cabin with a dense acrid smoke. ATC would not permit the aircraft onto a gate until the crew threatened an evacuation so three hours after landing they were towed to the gate. Some passengers and cabin crew experienced ill effects from the oil smoke.

Narrative: We diverted approximately 500 miles north northeast of our planned destination. The initial plan was to land; refuel; and then continue on to the filed destination when the weather lifted permitting us to land. That did not happen. We landed with approximately 9;500 LBS of fuel left on the aircraft; total flight time 10:18. The entire flight had been nominal and uneventful until being diverted and subsequently starting the APU on taxi in. We started the APU; and we taxied to a spot on the taxiway where controllers had asked us to park behind one other aircraft. Once the brakes were set; I proceeded with engine shut down. The APU had been started and was running approximately 4-5 minutes but once engine shut down occurred it began supplying bleed air to the packs; the entire Cabin filled with a very dense and opaque acrid white smoke. The burnt chemical aroma of the smoke being pumped into the cabin was noxious. The moment I recognized that smoke was entering the cabin I immediately had the APU bleed air turned off from the packs and the smoke stopped pouring into the cabin. A few moments later the APU experienced an 'AUTO SHUTDOWN' due to low oil and low pressure leaving the aircraft powerless; no conditioned cabin air; and with a cabin filled with TOXIC opaque smoke on an active TAXIWAY only battery power available. The smoke became so dense in the cabin (and dark from lowered window shades) that our Lead Flight Attendant asked permission to instruct the flight attendants to open ALL CABIN DOORS immediately to evacuate the smoke and ventilate the cabin. I agreed. Once the doors were opened the cabin smoke cleared within 5 minutes. There was a residual 'chemical' odor that lingered throughout the cabin even without conditioned air or power. The temperature in the cabin began to climb dramatically once we lost conditioned air from the packs. Just a few minutes after experiencing the APU auto shutdown; we noticed airport fire-rescue trucks heading to our aircraft rather rapidly with lights and sirens. We were later informed by ground personnel that they responded as a result of the smoke emanating from the tail of the aircraft (the APU compartment); and the opened cabin doors. The fire-rescue team witnessed this from across the field; without the flight crew requesting assistance. Passengers plus crew were now trapped on an aircraft without conditioned air; power; or working lavatories. The 31C OAT was now making the cabin a toxic sweat lodge. The cabin temperature climbed to 36C or 97F even with the doors open. That is when things with the passengers began to spiral out of control. After over two hours of sitting on a trashed toxic and powerless aircraft; people were becoming physically ill and vomiting; the passengers that weren't sick due to the toxic fumes were now affected by the stifling temperature onboard the aircraft and became more agitated the longer we sat parked. As the situation declined to anarchy; our Lead Flight Attendant informed me simply 'that if ground crew did not initiate a tow to the gate; he was going to initiate an emergency evacuation right there on the taxiway.' I have no doubt we would probably still be sitting there had we not threatened Ground with an emergency evacuation. We were towed to a gate which only took 12 minutes.We secured the aircraft and we entered a logbook entry regarding the APU failure and toxic air event. The entire crew was escorted through customs and transported to the Hotel for RON. The APU during start up ruptured and blew out all of its oil; allowing it to seep into the air conditioning packs. APU operated normally prior to our departure the night before with no indication of the impending failure. Alternates in this region are meaningless because the ATC authorities are in command of where you can go if an airport is unavailable for landing.

Data retrieved from NASA's ASRS site as of April 2012 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.