American Airlines flight 191 is regularly scheduled flight passengers operated by American Airlines from Chicago O'Hare International Airport to Los Angeles International Airport. On May 25, 1979, McDonnell Douglas DC-10-10 operated this flight crashed moments after taking off from Chicago. All 258 passengers and 13 crew on board were killed, along with two people on the ground. With 273 fatalities, it was the deadliest aviation accident ever in the United States, and the second deadliest aviation accident involving DC-10, behind Turkish Airlines Flight 981.
The National Transportation Safety Council (NTSB) found that when the jet started its take-off rotation, machine number one (left engine) was separated from the left wing, flipped the top of the wing and landed on the runway. When the engine is separated from the plane, it disconnects the hydraulic fluid channel that locks the leading edge wing blades in place and damages the three-foot portion of the left wing edge. The aerodynamic force acting on the wings results in an unusual retraction of the outboard patch. As the jet begins to climb, the left wing is damaged, without the engine, resulting in a much lower lift (halted) than the right wing, with its blades still in use and the engine working at full takeoff speed. The disturbed and unbalanced aerodynamics of the plane caused it to roll suddenly to the left until it was partially reversed, reaching a 112-degree bank angle, before crashing in an open field by a trailer park near the end of the runway. Separation of the engine is associated with damage to the pylon structure that holds the engine to the wing, caused by improper maintenance procedures used on American Airlines.
Video American Airlines Flight 191
Accident
On an accident flight, just as the plane reaches takeoff speed, Engine No.1 and its pylon assembly are separated from the left wing, tearing the 3-foot (0.91 m) section from the leading edge with it. The combined unit flipped the top of the wing and landed on the runway. Robert Graham, the maintenance supervisor of American Airlines, stated: "As the plane got closer, I saw what looked like steam or smoke of some kind coming from the leading edge of the No. 1 wing and machine pole. I noticed that Machine No. 1 bounced off up and down quite a bit and almost time when the plane was opposite to my position and started spinning, the engine slipped off, up from the top of the wing, and back to the runway.... Before jumping over the wings, the engine drove up and up as if it lifted and actually climbed.This did not strike the top of the wing in its path but instead followed a clear path from the airflow from the wings, above and above it, then dropped below the tail.The plane continued to climb normally until it started to turn left. And at that point, I think he will return to the airport. "
It is not known what is said in the cockpit within 50 seconds of the final impact, when the cockpit voice recorder loses power when the engine is released. The only audio associated with the damage collected by the recorder is the thumping sound (probably the sound of the separating engine), followed by the first officer who exclaims "Damn!", At which point the recording ends. This can also explain why Air Traffic Controls did not work in their efforts to emit crews and tell them that they lost the machine. This loss of power, however, proved useful in investigation, serves as a precise marker of what circuit in the vast DC-10 electrical system has failed.
In addition to engine failure, some related systems fail. The number one hydraulic system, powered by number one engine, fails but continues to operate through a motor pump that mechanically connects it with a three hydraulic system. The three hydraulic systems are also damaged and begin to leak fluid but the pressure and operation are maintained until impact. The two hydraulic systems are not damaged. The number one electric bus, whose generator plugged into the number one machine, failed, caused some electrical systems to be offline, especially the captain's instrument, the shake baton, and the slat disagreement sensor. While switches in the overhead panel will allow the captain to return power to his instrument, it is not used. It may be possible for the flight engineer to reach the backup power switch (as part of the abnormal list of conditions - not as part of their take-off emergency procedure) in an attempt to restore electric power to the number one electric bus. It will work only if the power failure is no longer present in the electrical system number one. Furthermore, to reach the switch, the aviation engineer must rotate his chair, release his seat belt, and stand up. Since the plane never rises more than 350 feet (110 m) above the ground and is in the air for only 50 seconds between when the engine is apart and when it falls, there is not enough time to perform such an action. However, the first officer flew the plane and the equipment continued to function normally. Since the wings and the engine are not visible from the cockpit, the crew is unlikely to know that the engine has crashed, only the failed.
Since it is no longer possible to cancel the takeoff at this point, the crew follows standard operating procedures for "machine" ascent. This procedure is climbing at the air velocity of takeoff (V 2 ) and the attitude (angle), as directed by the aviation director. A partial electric failure (generated by left No. 1 machine separation) means that both the crack warning and crack warning indicators are not operating. The crew, therefore, did not realize that the blades on the left wing pulled back. This retraction significantly increases the left-wing stall's speed. Thus flying at the airspeed takeoff airspeed causes the left wing to stall while the right wing still produces the elevator, so the plane turns sharply and uncontrollably to the left. Later, in the accident recreation simulator, it was determined that if they had climbed at a higher speed crash it could have been avoided.
The aircraft rises to about 325 feet (99 m) above the surface of the ground while spewing a trail of white fog fuel and hydraulic fluid from the left wing. The first officer has followed the director of the flight and raised the nose to 14 degrees, which reduces the air velocity from 165 knots (190 mph, 306 km/h) to the air velocity of 153 knots (176 mph; 283 km/h), the speed at which the aircraft can ride safely after a machine failure. However, the separation of the engine has disconnected the hydraulic fluid channel that controls the leading edge of the left wing and locks them in place, causing the paste (past to leave No. 1 machine) to pull back under the air load. The blade retraction lifted the left-wing stall's speed to about 159 knots (183 mph, 294 km/h), 6 knots (6.9 mph, 11 km/h) higher than the specified take-off air velocity (V 2 ) of 153 knots (176 mph; 283 km/h). As a result, the left wing enters a full aerodynamic stall.
With the left wing paused, the plane began to move to the left, rolling sideways until partially upside down at a 112-degree angle bank (as seen on Laughlin's photo) with its right wing above his left wing. Since the cockpit has been equipped with a closed-circuit television camera positioned behind the captain's shoulder and connected to view the screen in the passenger cabin, it is possible that passengers can watch this event from the cockpit when the aircraft pigeons to the ground. Is the camera's view disturbed by the loss of power from the unknown number one electric bus. The plane eventually crashed into a field of about 4,600 feet (1,400 m) from the end of the runway. A large piece of aircraft debris was thrown by a collision force into an adjacent trailer park, destroying five trailers and several cars. DC-10 also hit an old aircraft hangar located at the edge of the airport at the former location of Ravenswood Airport, which is used for storage.
In addition to 271 people on board, two employees in a nearby repair garage were killed and two others were badly burned. Accident occurrence is a field to the northwest of the intersection of Touhy Avenue (Illinois Route 72) and Mount Prospect Road on the fringes of Des Plaines and Mount Prospect, Illinois.
Maps American Airlines Flight 191
Investigation
The aircraft involved is a registered McDonnell Douglas DC-10-10 N110AA . It was delivered on February 25, 1972, and at the time of the accident, the plane had just recorded time flying under 20,000 hours for seven years. The jet is powered by three General Electric CF6-6D engines. A review of aircraft flight records and aircraft maintenance showed that no mechanical differences were recorded for May 11, 1979. On the day of the crash, violating standard procedures, records were not removed from aircraft, and destroyed in accidents.
Disasters and investigations received widespread media coverage. The impact on the public was heightened by the dramatic effect of amateur photographs taken from the aircraft rolls published on the front page of the Chicago Tribune on Sunday two days after the accident. There were some preliminary reports that a collision with a small plane had been the cause of the accident. This apparently was the result of the discovery of a small plane between the wreckage at the crash site. Deputy chairman of the National Transportation Safety Board Elwood T. Driver, in a press conference, was photographed holding a broken bolt and nut, implying that these parts were the cause of the accident. Small plane parts were then determined to have been on the ground at the time of the accident, at Ravenswood Airport of the former public aviation, a facility that has been out of service for several years. An owner there has sold used aircraft parts from the rest of the hangar building.
The NTSB determines that the loss of a single engine and the asymmetrical resistance caused by damage to the leading wing should not be enough to cause the pilots to lose control of their aircraft; The aircraft should be able to return to the airport using the two remaining machines. The NTSB examines the effects of engine separation on aviation, hydraulic, electrical, and aircraft control systems. Unlike other aircraft designs, the DC-10 does not include a separate mechanism for locking the main expanded main edge, relying only on hydraulic pressure in the system. The NTSB determines that the machine tears through several hydraulic channels because it is separated from the DC-10 wing, causing a loss of hydraulic pressure; the airflow above the wing forces the left-wing bar to pull back, causing a kiosk over the left wing. In response to the accident, slat relief valves are mandated to prevent retracting of the slats in case of damage to the hydraulic lines.
The debris was too fragmented to determine the exact position of the wheel, elevator, flap, and blades before impact and examination of eyewitness photographs only showed that the right wing bar was fully extended when the crew tried unsuccessfully to repair their steep rolls at. The left wing bar can not be determined from the blurred color photographs, so they are sent to a laboratory in Palo Alto, California for digital analysis, a process that pushes the limits of 1970s technology and requires large, complicated, and expensive. equipment. The photographs were reduced to black and white, which made it possible to distinguish the blades of the wings themselves and thus prove that they were withdrawn. In addition, it is also verified that the tail section of the aircraft is not damaged and the landing gear is down.
Wind tunnel tests and flight simulators are performed to help understand the plane's trajectory after the engine is released and the left wing bar is pulled back. The tests determined that damage to the front wing and retraction of the blades increased the left-wing stall velocity from 124 knots (143 mph) to 159 knots (183 mph). The DC-10 incorporates two warning devices that may have alerted the pilot to an upcoming kiosk: warning lights of slat battles, which should be illuminated after an unusual crack pull, and a shake stick on the captain's control column, which activates the cap to the stall speed. Both of these warning devices are powered by electric generators driven by number one engines. Both systems become non-functional after the machine's loss. The first officer's control column is not equipped with a shaker; the device was offered by McDonnell Douglas as an option for the first officer, but American Airlines chose not to install it on its DC-10 fleet. Stick shakers for both pilots became mandatory in response to this accident.
Machine separation
The witnesses of the accident were in a universal agreement that the plane did not hit a foreign object on the runway. Also, no wing or other component parts of the aircraft were found along with a separate engine, other than the supporting pole, leading investigators to conclude that nothing else was detached from the fuselage and crashing into the engine. Therefore, the separation of the assembly of the engine/pylon can only result from a structural failure.
During the investigation, the examination at the pylon attachment points revealed some damage done to the wing pile mounting bracket that matched the rear pin pin form of the pylon. This means that the installation of the pylon peg has hit the mounting bracket at some point. This is some important evidence, because the only way the pylon fitting can strike the wing mounting bracket in an observed way is if the bolt that holds the pylon to the wing has been removed and the engine/pylon assembly is supported by something other than the plane itself. Therefore, researchers can now conclude that the damage observed in the rear mountain pylon has existed before the accident actually occurred, not caused by it.
NTSB determined that damage to the pylon of the left wing machine had occurred during a previous engine change at the American Airlines maintenance facility in Tulsa, Oklahoma between March 29 and 30, 1979. On that date, the aircraft had undergone a routine service, in which the machine and pylon had been removed from the wing for inspection and maintenance. The removal procedure recommended by McDonnell-Douglas asks the machine to slip off the pole before removing the pole itself from the wing. However, American Airlines, as well as Continental Airlines and United Airlines, have developed different procedures that save about 200 hours per aircraft and are "more important from a safety standpoint, it will reduce the number of disconnections (systems such as hydraulics and fuel lines, power lines, and cable) from 72 to 27. "This new procedure involves the removal of the engine and pylon assembly as a single unit, not as an individual component. The implementation of United Airlines involves the use of overhead cranes to support engine/pylon assembly during discharge and installation. The method chosen by American and Continental procedures supports the assembly of engines/pylons with large hold of forklifts.
It is known that if the forklift is incorrectly positioned, the engine/pylon assembly will not stabilize as it is handled, causing it to shake like a saw and pylon jams against the wing attachment points. The forklift operator is only guided by hand and voice signals, because it can not see directly the point of the meeting between the pole and the wing. Positioning must be very accurate or structural damage can occur. Due to the problem, maintenance work on the N110AA did not go well. Mechanics start severing machines and pylons, but there is a shift change in the middle of work. As work continued, the pole was jammed in the wings and the forklift had to be re-positioned, resulting in unseen structural damage to the wing pylon bonding points. Structural damage is not enough to cause immediate failure. However, damage to the mountain developed into fatigue cracking, and worsened with every cycle of takeoff and landing for eight weeks after maintenance on the N110AA. Finally, the damaged rear pylon pole is attenuated in such a way that it is no longer able to support even normal flight loads, and fails. Due to the absence of this attachment, the engine, at full takeoff power, and its pole fell off the wing. The structure surrounding the advanced pylon mounts then fails from the resulting pressure.
The DC-10 fleet inspection of the three airlines revealed that while the United Airlines hoist approach seems harmless, there are several DC-10s in America and Continental that have suffered fatal damage to their pylon mounts. The field service representative from McDonnell-Douglas stated the company would "not push this procedure due to risk elements" and so American Airlines advised. McDonnell-Douglas, however, "has no authority to approve or disapprove of its customer maintenance procedures."
Possible cause
The findings of an investigation by the National Transportation Safety Agency released on December 21, 1979:
The National Transportation Safety Council determines that the probable cause of this accident is the asymmetrical kiosk and the fuselage of the forthcoming plane due to the uncommon retraction of the left-wing left-hand edge and the loss of kiosk warnings and indications of slat disagreement resulting from damage resulting from maintenance leading to engine separation. 1 and pylon assembly at a critical point during takeoff. Separation resulted from damage by improper maintenance procedures that led to the failure of the pylon structure.
Contributing to the cause of the accident is the vulnerability of pile design inherent to maintenance defects; vulnerability of the leading slat system design to the damage that produces the asymmetry; a deficiency in the Federal Aviation Administration's oversight and reporting system that fails to detect and prevent the use of improper maintenance procedures; lack of practice and communication among operators, manufacturers and FAAs that fail to determine and disseminate specific matters concerning previous maintenance damage incidents; and intolerance of the operational procedures specified for this unique emergency.
Legacy DC-10
Flight Accident 191 brings hard criticism from media related to safety and design of DC-10. DC-10 has been involved in two accidents related to cargo door design, American Airlines Flight 96 (1972) and Turkish Airlines Flight 981 (1974). The separation of one engine from its mounts, the widespread publication of the aircraft's dramatic drawing lost seconds before the crash, and a second photo of a fireball resulting from a collision, raising widespread concern about the security of DC-10. The final blow to the plane's reputation was handled two weeks after the accident, when it was blocked by the FAA. Although the plane itself was later released, damage to the public eye was already under way.
The investigation also revealed other DC-10s with damage caused by the same faulty maintenance procedures. The wrong procedure was banned, and the aircraft type went on to have a long career as a passenger and cargo plane. In response to this accident, American Airlines was fined $ 500,000 by the US government for improper maintenance procedures.
On June 6, 1979, two weeks after the accident, the Federal Aviation Administration suspended the type certificate for DC-10, thus underlying all DC-10s under its jurisdiction. It also imposes special air regulations that prohibit DC-10 from US airspace, which prevents foreign DC-10s that are not under FAA jurisdiction to fly domestically. This is done when the FAA investigates whether the engine installation and aircraft pylon design meet the relevant requirements. After the FAA was satisfied that the maintenance issue was mainly due to faults and not the actual aircraft design, the type certificate was restored on July 13 and special air regulations were lifted. However, the type certificate was altered, stating that "... the removal of the machine and the pylon as a unit would soon make the aircraft unfeasible to fly."
Another DC-10, performing Western Airlines Flight 2605, crashed in Mexico City after a red-eye flight from Los Angeles nearly 5 months after the 1934 American Airlines Flight crash. The Western Airlines DC-10 crash, however, was due to low visibility and attempts to land on a sealed runway. Ironically, another DC-10 accident, United Airlines Flight 232, ten years later, restored some of the aircraft's reputation. Despite the loss of the engine, all flight controls, emergency landing in large fireballs (caught on video by local news crews), and killed 111 people, 185 people survived the accident. Experts praised the powerful DC-10 construction as part responsible for the high number of survivors, despite the efforts of the main crew responsible.
The DC-10 accident at the end of November, Air New Zealand Flight 901, exactly six months after Flight 191, added to the negative reputation of DC-10. The Flight 901 collision, an Antarctic plane crashing into a mountain, was caused by several human and environmental factors unrelated to the DC-10 airworthiness, and the plane was then completely relieved of the accident.
Despite initial security concerns, DC-10 aircraft continued to serve passenger airlines for more than 30 years after the fall of Flight 191. In the end, twin-engine, fuel-efficient, dual-engined aircraft from Boeing and Airbus and not a security issue. which eventually ended the passenger career of DC-10 (however, security issues ended up ending production <-i> DC-10 in 1983). Many retired DC-10 passengers have since been converted into use of all cargo. DC-10 cargo, along with its derivatives, MD-11, forms the backbone of the FedEx Express fleet. DC-10 has been upgraded with a glass cockpit from the MD-11, thus converting it to MD-10. American Airlines retired DC-10 last in 2000 after 29 years of operation. In February 2014, Biman Bangladesh Airlines operated the final flight of DC-10 passengers. DC-10 continues to be widely used in air freight operations, and military variants also operate.
Victim
Passenger and crew nationality
Airplane crew
Captain Walter Lux, 53, has flown the DC-10 since it was introduced eight years earlier. He has logged about 22,000 flight hours, of which about 3,000 are in DC-10. He is also eligible to lead 17 other aircraft, including DC-6, DC-7, and Boeing 727. First Officer James Dillard, 49, and Flight Engineer Alfred Udovich, 56, are also highly experienced: 9,275 hours and 15,000 hours each , and among them, they have 1830 hours of experience flying in DC-10.
Passenger
Some of the most notable victims of the 191 Flight crash are: Itzhak Bentov, an inventor of Czech-American Israeli-American biomedicine (cardiac catheter) and New Age writer ( Liquor Pendulum Wild and Cosmic Book ).
Memorial
For 32 years there was no permanent warning for the victims. Funding was obtained for warning in 2009, through a two-year effort by the 6th grade of the Decatur High School class in Chicago. The memorial, a 2-foot (0.6 m) tall concave wall - tall with interlocking bricks displaying the names of casualty victims, was officially presented at a ceremony on October 15, 2011. The memorial was located at Lake Park at an angle Northwest. from Lee and Touhy Avenues, two miles east of the crash site.
In-media depictions
The National Geographic Channel's cable/satellite TV channel produced a documentary about the accident, and an episode of <<> The Second of Disasters titled "Chicago Plane Crash" detailing the accident and including an investigative press conference film. The Canadian television series Mayday charted an accident on the episode "Catastrophe at O'Hare", which was aired in the US on the Smithsonian Channel Air Disasters television series.
Chicago folk singer Steve Goodman wrote the song "Ballad of Flight 191 (They Know Everything About It)" in response to the crash and subsequent investigation as the inaugural song for a series of topical songs broadcast on National Public Radio in 1979. The Novel Michael Crichton Airframe describes this incident in detail as an example to the reader how "a good airplane (DC-10)" can be "destroyed by a bad press".
See also
- Flight accidents and incidents
- Flight security
- A similar accident caused by the separation of the machine
- China Airlines 358 Flight
- El Al Flight 1862
References
External links
- NTSB Accident Report
- "Public Lessons Learned from Accidents - American Airlines Flight 191" (archive)
- Aircraft Flight - American Airlines Flight 191
- Flight 191 Remember (Fox Chicago website, archive)
- Pre-crash images from Airliners.net
- NTSB Possible Cause Report
- News report at The Museum of Classic Chicago Television
Source of the article : Wikipedia
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