On May 25, 1979, a series of images were captured from near the terminal of Chicago's O'Hare International Airport. The images showed an American
Airlines DC-10, rolled 90 degrees to the left, with one engine missing. Another image showed the fireball from the impact of the aircraft. On board
were 258 passengers, and 13 crew. There were two fatalities on the ground as well.
The Aircraft and crew
The aircraft in use that day was a seven year old DC-10-10, registered as N110AA. It had been delivered new to the airline in February of 1972, and
had just under 20,000 hours on it at the time of the crash. The pilot had approximately 3,000 hours in the DC-10, and 22,000 hours total. The First
Officer and Flight Engineer had just over 1,800 hours in the DC-10, and a combined almost 25,000 hours total.
The DC-10 had been introduced in 1971. The -10 series was designed to go under 4,000 miles with a typical load, and 2,700 miles with a maximum load.
It started out with a poor safety record, beginning in 1972. The cargo doors were designed to open out, instead of being plug type doors, and there
were several incidents of the door opening in flight, which directly led to one aircraft crashing
American Airlines DC-10:
On May 25, 1971 American 191 departed the gate, and taxied to the runway. At approximately 3pm, they began to take off, with everything appearing
normal. As the aircraft reached takeoff speed, there was a thump heard on the CVR, followed by the pilot saying "Damn", at which point the CVR ended
As the aircraft reached takeoff, the left engine suddenly rotated up, and detached from the wing. As it detached, it went up and over the wing,
without hitting the aircraft, but damaging the electrical bus, and two of the three hydraulic systems. A maintenance supervisor noticed that the
engine was bouncing more than normal, and there was some kind of vapor trail coming from the area of the engine. He witnessed the engine separate and
go over the wing. It's shortly after that, when the pictures were taken.
After the engine separated, the crew lost several vital systems, including the leading edge slat indicator, and the stick shaker.
On take off and landing, the leading edge of the wing has a series of panels that extend with the flaps. This allows the aircraft to fly slower, and
be more stable. The stick shaker is designed so that when the aircraft is about to enter an aerodynamic stall, when the wing angle gets to where air
can't flow over it and generate lift, the control column will shake, alerting to the pilot that they're about to stall.
On American 191, when the hydraulic systems were damaged, the left hand slats retracted. This caused that wing to have a much higher stall speed than
the right wing. With the stick shaker being disabled, the crew had no indication that either the slats had retracted, or that they were entering a
stall. The engine placement was such that the crew couldn't look back and see that the engine had separated. They would have thought that it was
just a failure. The crew followed procedure, and flew an engine out departure, which called for them slowing to their best climb speed. It was later
determined in the simulator, that if the crew had kept the speed up, or increased the speed during the climb, the crash could have been averted, and
the aircraft saved.
After reaching 325 feet, the aircraft rolled to 112 degrees left wing low, and crashed near a trailer park off the end of the runway. The aircraft
hit near a large petroleum tank, but fortunately didn't hit it. Wreckage of the aircraft hit the trailer park, destroying 5 trailers and several
vehicles. Two mechanics at a repair shop near the impact site were killed.
The Aftermath and cause
On June 16th, the FAA revoked the airworthiness certificate of the DC-10, and banned any DC-10 owned by foreign carriers from operating in United
On December 21st, the NTSB released a report blaming American Airlines for the accident. On March 29th and 30th, the aircraft was in Oklahoma for an
engine change. American, Continental, and United were all found to be using a shortcut to change the engine, instead of following McDonnell Douglas
procedures. Under the MD procedure, the engine was to be removed, and placed on an engine stand, and then the pylon is removed separately.
Under the shortcut, the entire assembly was removed as one unit, and supported with a forklift as it was detached. This reduced the time of the
procedure by 200 man hours, and the disconnects required to 27 from 72. But, it was also much harder to hold the engine assembly level as it was
removed. At some point during the procedure, the back of the engine was lifted higher than the front, and the back engine mount was damaged. During
the subsequent months, a fatigue crack appeared through the mount. During takeoff on the date of the crash, the mount failed, allowing the engine to
rotate on the front mount, which then failed.
NTSB Accident report
edit on 2/6/2016 by Zaphod58 because: (no reason