American 191, Chicago, May 25, 1979

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:



The Flight

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 suddenly.

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.





The Impact

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 States airspace.

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.

Sources:

NTSB Accident report
aviation-safety.net...
lessonslearned.faa.gov...
www3.gendisasters.com...

I thought I remembered the DC-9 losing engines?

Either way is horrible.

Honestly put yourself in the shoes of those mechanics... Regardless of who is to blame.

This actually happened on my dad's birthday and he lived not far from that airport back then

So what is your take on the incident? Mechanic error pilot error or owner error?

a reply to: tinner07

It was all on the mechanics and airline. The crew contributed, by slowing down, but that was what the procedure called for. They might have seen they were losing hydraulics, and lost the engine, but there was no way for them to understand that the engine had actually separated from the aircraft. Without realizing that, there was absolutely nothing they could do to save the aircraft.

I agree it was mechanics. the fact they followed airline procedures makes it airlines. Just out of curiosity were the mechanics at the time union or non union? do you know?

a reply to: tinner07

I believe they were union, but I'm not 100% certain.

There went part of my argument....

but the mechanics deviated from normal protocol as dictated by the airlines... the true culprit in this case would be the consumer.. kinda maybe....

a reply to: tinner07

The procedure was written by the manufacturer, and the airlines deviated to save time. MD couldn't make the airlines follow their procedure, and it bit them hard this time. From what I've read the airlines actually wrote the procedure to remove engine and pylon as one unit.

My brother and I used to go to local airport (upstate NY) and begger captains for A/C tours.

This was late 70' early 71' before all the security stuff. We convinced an AA captain to give one of his DC-10.

We got full exterior walkaround tour followed by an interior tour of cockpit, cabin and even the elevator to the galley.

The captain was very gracious and remarkably patient with 10 and 12 year olds wide eyed and asking all manner of questions.

Never forget that experience and have always prayed he was not the captain on the Chicago flight.

That was a bad day for commercial aviation.

From what I've read the airlines actually wrote the procedure to remove engine and pylon as one unit.

I agree. and it ended in disaster.

fast forward to today and the corporations writing their own laws that get passed and what does that say???

Was this the accident that was caused by maintenance crews cutting corners and cracking the engine mount?

Apparently there are some very strange occurrences at the crash sight at night.

a reply to: sg1642

Yes, but they were cutting corners on the orders of the airline to save time. One report I saw about it said that during the engine change, they went to lunch, and while they were at lunch, the forklift shifted slightly, and the back of the engine dropped a little bit. When they went to lift the engine back, they lifted it too fast, and it hit the mount and damaged it.

a reply to: sg1642

It wouldn't be the first time I've heard stuff like that. In 1972, Eastern Airlines 401 crashed in the Everglades, due to crew error. They took parts from it, and put them on other aircraft, and many people reported seeing the ghosts of the pilots of 401. People that had never met them were able to identify them from photographs.

www.near-death.com...

originally posted by: Zaphod58
a reply to: sg1642

Yes, but they were cutting corners on the orders of the airline to save time. One report I saw about it said that during the engine change, they went to lunch, and while they were at lunch, the forklift shifted slightly, and the back of the engine dropped a little bit. When they went to lift the engine back, they lifted it too fast, and it hit the mount and damaged it.

I watched a documentary about it not too long ago apparently the investigators came out and said it was due to a snapped bolt to begin with before realising they were wrong.

That must have been a horrific last few moments for everyone on the aircraft that day.

a reply to: sg1642

The FAA investigator took a huge chance by telling his superiors they needed to ground the aircraft. But he was right. When they started inspecting others, they found a number of damaged engine mounts, because of this same procedure. Fortunately, this was the only accident related to it. It could have been a lot worse.

originally posted by: Zaphod58
a reply to: sg1642

The FAA investigator took a huge chance by telling his superiors they needed to ground the aircraft. But he was right. When they started inspecting others, they found a number of damaged engine mounts, because of this same procedure. Fortunately, this was the only accident related to it. It could have been a lot worse.

Well it should have had alarm bells ringing when the engine fell off in the first place. Sometimes taking a chance is the right thing to do. The sad thing is mistakes like that have to be made so we can learn from them.

With regards to your other post that's some strange stuff indeed. Apparently at the 191 crash site people see lights at the side of the road and can hear screams. One man claimed to come face to face with a smouldering victim smelling of kerosene. Obviously most of these stories are hearsay and folklore but it makes you wonder.

a reply to: sg1642

There have been a couple of high profile accidents that have had mysterious things happening afterwards. It's definitely something interesting.

a reply to: sg1642

There is no good ending to a crash... in my training with the USAF I had to listen to quite a few CVR's... it was tolerable for the ones that nothing the crew could do could change the outcome... the hard ones to listen to were the ones where the crew screwed up by the numbers till it was to late.

I imagine though if you have to be on a plane going down id rather be crew than a passenger.