Pan Am Flight 125
Encyclopedia
Pan Am Flight 125 was a scheduled flight from London Heathrow Airport
to New York's John F. Kennedy International Airport
on March 10, 1987. It suffered a cargo door failure that pointed to a fundamental design flaw in the early model Boeing 747
s, a failure mode that was repeated with fatal consequences on United Airlines Flight 811
.
Boeing 747–121 (registration number ) named Clipper Ocean Pearl with 245 passengers and crew experienced an incident involving the forward cargo door. According to Pan Am and Boeing
officials who investigated this incident, the flight crew experienced pressurization problems as the aircraft was climbing through about 20,000 feet. The crew began a descent and the pressurization problem ceased at about 15,000 feet. The crew began to climb again, but around 20,000 feet, the cabin pressure altitude began to rise rapidly again. The flight returned to London.
According to the people who examined the aircraft, the cargo door had been closed manually and the manual master latch lock handle was stowed, in turn closing the pressure relief doors and extinguishing the cockpit cargo door warning light. Subsequent investigation on N740PA revealed that the latch lock sectors had been damaged and would not restrain the latch cams from being driven open electrically or manually. It was concluded by Boeing and Pan Am that the ground service person who closed the cargo door apparently had back-driven (opened) the latches manually after the door had been closed and locked. The damage to the sectors, and the absence of other mechanical or electrical failures supported this conclusion.
Further testing of the door components from N740PA and attempts to recreate the events that led to the door opening in flight revealed that the lock sectors, even in their damaged condition, prevented the master latch lock handle from being stowed, until the latch cams had been rotated to within 20 turns (using the manual half-inch socket drive) of being fully closed. A full cycle, from closed to open, is about 95 turns with the manual drive system.
experienced the loss of its cargo door after climbing out of Honolulu, Hawaii
. The cargo door in this incident was lost in-flight, which caused a portion of the aircraft and 9 passengers to separate from the aircraft after explosive decompression
.
of United Airlines Flight 811
.
London Heathrow Airport
London Heathrow Airport or Heathrow , in the London Borough of Hillingdon, is the busiest airport in the United Kingdom and the third busiest airport in the world in terms of total passenger traffic, handling more international passengers than any other airport around the globe...
to New York's John F. Kennedy International Airport
John F. Kennedy International Airport
John F. Kennedy International Airport is an international airport located in the borough of Queens in New York City, about southeast of Lower Manhattan. It is the busiest international air passenger gateway to the United States, handling more international traffic than any other airport in North...
on March 10, 1987. It suffered a cargo door failure that pointed to a fundamental design flaw in the early model Boeing 747
Boeing 747
The Boeing 747 is a wide-body commercial airliner and cargo transport, often referred to by its original nickname, Jumbo Jet, or Queen of the Skies. It is among the world's most recognizable aircraft, and was the first wide-body ever produced...
s, a failure mode that was repeated with fatal consequences on United Airlines Flight 811
United Airlines Flight 811
United Airlines Flight 811 experienced a cargo door failure in flight on Friday, February 24, 1989, after its stopover at Honolulu International Airport, Hawaii...
.
Summary
On March 10, 1987, a Pan American World AirwaysPan American World Airways
Pan American World Airways, commonly known as Pan Am, was the principal and largest international air carrier in the United States from 1927 until its collapse on December 4, 1991...
Boeing 747–121 (registration number ) named Clipper Ocean Pearl with 245 passengers and crew experienced an incident involving the forward cargo door. According to Pan Am and Boeing
Boeing
The Boeing Company is an American multinational aerospace and defense corporation, founded in 1916 by William E. Boeing in Seattle, Washington. Boeing has expanded over the years, merging with McDonnell Douglas in 1997. Boeing Corporate headquarters has been in Chicago, Illinois since 2001...
officials who investigated this incident, the flight crew experienced pressurization problems as the aircraft was climbing through about 20,000 feet. The crew began a descent and the pressurization problem ceased at about 15,000 feet. The crew began to climb again, but around 20,000 feet, the cabin pressure altitude began to rise rapidly again. The flight returned to London.
Cause
When the aircraft was examined on the ground, the forward cargo door was found open about 1.5 inches along the bottom with the latch cams unlatched and the master latch lock handle closed. The cockpit cargo door warning light was off.According to the people who examined the aircraft, the cargo door had been closed manually and the manual master latch lock handle was stowed, in turn closing the pressure relief doors and extinguishing the cockpit cargo door warning light. Subsequent investigation on N740PA revealed that the latch lock sectors had been damaged and would not restrain the latch cams from being driven open electrically or manually. It was concluded by Boeing and Pan Am that the ground service person who closed the cargo door apparently had back-driven (opened) the latches manually after the door had been closed and locked. The damage to the sectors, and the absence of other mechanical or electrical failures supported this conclusion.
Further testing of the door components from N740PA and attempts to recreate the events that led to the door opening in flight revealed that the lock sectors, even in their damaged condition, prevented the master latch lock handle from being stowed, until the latch cams had been rotated to within 20 turns (using the manual half-inch socket drive) of being fully closed. A full cycle, from closed to open, is about 95 turns with the manual drive system.
Related incident
A similar incident occurred February 24, 1989. United Airlines Flight 811United Airlines Flight 811
United Airlines Flight 811 experienced a cargo door failure in flight on Friday, February 24, 1989, after its stopover at Honolulu International Airport, Hawaii...
experienced the loss of its cargo door after climbing out of Honolulu, Hawaii
Honolulu, Hawaii
Honolulu is the capital and the most populous city of the U.S. state of Hawaii. Honolulu is the southernmost major U.S. city. Although the name "Honolulu" refers to the urban area on the southeastern shore of the island of Oahu, the city and county government are consolidated as the City and...
. The cargo door in this incident was lost in-flight, which caused a portion of the aircraft and 9 passengers to separate from the aircraft after explosive decompression
Explosive decompression
Uncontrolled decompression refers to an unplanned drop in the pressure of a sealed system, such as an aircraft cabin and typically results from human error, material fatigue, engineering failure or impact causing a pressure vessel to vent into its lower-pressure surroundings or fail to pressurize...
.
In the Media
Pan Am Flight 125 is shown in the Air Crash Investigation/MaydayMayday
Mayday is a distress signalMayday or May Day may also refer to:* May Day, a holiday on or around May 1** International Workers' Day* Mayday, Colorado- Music :* Mayday , an electronic music festival* Mayday...
of United Airlines Flight 811
United Airlines Flight 811
United Airlines Flight 811 experienced a cargo door failure in flight on Friday, February 24, 1989, after its stopover at Honolulu International Airport, Hawaii...
.