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Tag Archives: Boeing 707





Pretend you’re the pilot of a large jetliner.  You’ve completed pre-flight checks, both inside and outside, and are ready for takeoff.  As you climb, the plane begins to vibrate and then pitch to one side.  The number two engine then separates and you are faced with a decision – jettison the remaining fuel on the aircraft or make a heavy landing with fuel on board.  While engine separations are not frequent occurrences of air travel, they can have tragic consequences for both the plane and the surrounding area.  During the course of this blog, we’ll review two key cases involving such incidents.

In May 1979 a McDonnell Douglas DC-10 (Flight 191) was making a regularly scheduled passenger flight from O’Hare International Airport in Chicago to Los Angeles International Airport.  Moments after takeoff, the aircraft plummeted downward, killing all 258 passengers along with the crew of thirteen and two on the runway.  A subsequent investigation by the FAA revealed the number one engine separated from the left wing, flipping over the top and then landing on the runway.  During the separation from the wing, the engine severed several hydraulic lines which locked the leading edge wing slats into place, as well as damaging a three-foot section of the wing.  As the plane began to climb, it experienced a state of uncontrolled aerodynamics, in which the left wing provided minimal lift compared to that of the right wing while the engine was at full throttle.  This condition caused the aircraft to roll abruptly to the left, reaching a bank angle of 112 degrees before crashing.

While the cause of the DC-10 engine loss was later determined to be due to a damaged pylon structure connecting the engine to the wing, several other factors also played a role in the crash.  The hydraulic system powered by engine number one actually failed but ran from motor pumps connecting it to the engine three systems.  While hydraulic system three was also damaged, it continued to provide pressure until the crash in spite of leaking fluid.  Electrical problems were also a factor in the crash of Flight 191.  The number one electrical bus, attached to the number one engine, failed, resulting in several electrical systems going offline including the flight captain’s instruments, stick shaker and wing slat sensors.  As a result of the partial electrical failure, the flight crew only received a warning about the number one engine failure – not its loss.  Though the crew had a closed circuit television screen behind the pilot from which to view the passenger compartments, it too was subject to the loss of power from the engine.  After the Flight 191 incident and three other DC-10 crashes during the 1970s, a number of major airlines began to phase out the DC-10 in the early 1980s in favor of newer and more fuel- efficient jetliners such as the Boeing 757 and 767.  While the phaseout had more emphasis on fuel efficiency, the safety of the aircraft cast a cloud over its service.

The DC-10 wasn’t the only wide-body jet to experience engine separation.  In October 1992 an El Al Israeli Airlines Boeing 747-200 cargo plane (Flight 1862) with three crew members and one passenger on board, began a flight from John F. Kennedy Airport , New York to Ben Gurion International Airport, Tel Aviv with an intermediate stop at Schiphol Airport, Amsterdam.  Weather conditions were favorable at the time of departure with all pre-flight checks performed, with no defects found.  About ten minutes out of Schiphol, the flight data recorder indicated both engines 3 and 4 and their connecting struts had left the aircraft.  The co-pilot transmitted an emergency call to Schiphol, requesting a return to the airport.  However, the aircraft could not make a straight-in approach, due to both altitude and proximity to the airport.  Therefore, the air traffic controller had to vector the El Al plane back to the airport by flying a pattern of descending circles to lower the altitude for a final approach.  About five minutes into the flight pattern, the flight crew informed the controller of the loss of engines three and four and were beginning to experience flap control problems.  The controller directed a new heading to the flight crew, but noticed the plane was taking 30 seconds to change headings.  About three minutes later, the flight crew informed air traffic control they were receiving audible warnings indicating a lack of control and low ground proximity.  Approximately twenty-five seconds later, the aircraft crashed into an eleven-story apartment building, about seven miles from Schiphol Airport.

Both number 3 and number 4 engine struts were recovered from Naarden Harbour, just east of Amsterdam with both engines attached to the struts.  Remaining parts of the aircraft were located within a thousand foot radius of the impact.  From an analysis of the parts and their placement, investigators were able to determine the number 3 engine separated first, traveling in an outboard direction, striking engine 4 and causing it and the supporting strut to separate from the plane.  The engine struts or pylons are designed as two-cell torque boxes absorbing vertical, horizontal and torsional thrust loads to the wing, acting as an aerial shock absorber.  The Boeing 747 pylon was supported internally by five fuse pins, which provide enough strength to hold the pylons in place with the exception of extreme loads, in which the pins fail, allowing the engine to break away without damaging the wing fuel tanks.  This philosophy was adopted by Boeing from experiences with the earlier 707 and 727 models, in which a number of incidents of both in-ground and mid-air engine separations occurred.  The crash of the El Al jetliner was attributed to a failure of a center fuse pin in the number 3 engine strut.  The pin cracked due to metal fatigue and was a bottle bore design.  The FAA issued a directive in 1979 requiring airlines to conduct inspections of the fuse pins every 2,500 flight hours as the bottle design was prone to fail at that point.  The El Al 747 was one of a few aircraft which had not replaced their bottle pin units.  As a result of the El Al crash and two other 747 crashes, the FAA mandated a retrofit of all Boeing 747 wing struts in 1995.  The new strut design offered increased protection in the event of an engine separation, while still using fuse pins to protect the wing tank from damage during ground impact.

As the two previous cases indicate, engine separations may result from a number of problems.  Sometimes it’s a matter of faulty parts, while lack of proper maintenance plays a role in others.  The overall design of the aircraft itself may be a factor.  However, the safe operation of an aircraft requires a continual interplay of aviators, air controllers, engineers and the flying public  to promote flight safety.



100 And Growing


When one considers prominent German-Americans, names such as Eisenhower, Nimitz, Kaiser and Kissinger come to mind.  However, another German-American, not often cited, may leave perhaps a greater legacy.

William E. Boeing was born in Detroit, Michigan in 1881 to Wilhelm Boing from Hagen-Hohenlimburg Germany and Marie M. Ortmann from Vienna, Austria.  The senior Boeing was a mining engineer, who became wealthy as a result of holdings of timber lands and mineral rights near Lake Superior.  After study abroad in Switzerland, Boing added an e to his name, to make it sound more Anglo.  He then entered Yale, but left before graduating to join the family timber business in 1903. Buying a large tract of forest on the Pacific side of the Olympia Peninsula in Washington, Boeing began building  boats as well as acquiring several lumber operations.

During a business trip to Seattle in 1909, Boeing saw his first plane and soon developed a keen interest in aviation. Within a few months, Boeing was taking flying lessons at the Glenn L. Martin Plant in Los Angeles and had ordered a Martin TA Hydoraeroplane.  Martin even sent one of his test pilots up to Seattle to give Boeing lessons on site.  When the test pilot crashed the aircraft during a test flight, he informed Boeing replacement parts would not be available for months. The problem frustrated Boeing, who had just received his pilot’s certificate.  After studying both the plane and the parts distribution at Martin, Boeing approached a friend of his, Commander George Conrad Westervelt, USN.  When Boeing suggested to Westervelt that they could build their own plane in less time, Westervelt agreed and they formed their own aircraft company – B&W.  Their first aircraft, the B&W seaplane was an instant success with Boeing purchasing an old boat factory on the Duwamish River outside Seattle.

When the United States entered World War I, Boeing and Westervelt received a government contract for fifty of the B&W seaplanes, with Boeing changing the name of fledgling company to Pacific Aero Products Company.  By the end of the war, Boeing began to emphasize commercial aircraft, in addition to providing a government sponsored air mail service.

The air mail service was a result of the commercial aviation market flooded with surplus World War I aircraft, which were relatively inexpensive compared with the cost of new models.  Boeing had to diversify at this point, selling furniture, and a series of flat-bottomed boats called sea sleds.  Within a few years, Boeing began to realize a profit from the overhaul of government aircraft and the sale of a few new models.  During the 1920s and early 1930s, Boeing would become a major producer of fighter planes for the Army Air Corps.

In 1925 federal law allowed public bid for air mail contracts.  Boeing received the contract, but needed a fleet of twenty six planes to serve the Chicago to San Francisco route by July 1, 1927. As a guarantee, Boeing drew $500,000 of his own money to serve as a bond for the effort. These aircraft were composed of Boeing’s latest design, the Model 40, which had an open cockpit for the pilot with an enclosed cabin for two additional passengers.  The mail service proved to be an unexpected market coup for Boeing, allowing him to haul passengers for a fee and start a new airline, Boeing Air Transport.  It wasn’t long before Boeing cornered the market in both aviation sectors.

In 1929 Boeing acquired Pacific Air Transport, merging it with both the Boeing Airplane Co. and Boeing Air Transport. The new company was named United Aircraft And Transport Company. Later the same year, United purchased both the Pratt&Whitney engine and Hamilton Standard Propeller companies, as well as Chance Vaught Aircraft.  To expand its airline service, Boeing acquired National Air Transport the following year.

By 1934 Boeing’s success began to draw the attention of the federal government.  In June of that year the Air Mail Act was passed by Congress, by which aircraft manufacturers had to divest themselves of any airline services.  As a result of this split, Boeing’s holdings were formed into three companies:  United Aircraft Corporation, which manufactured aircraft in the eastern United States (now United Technologies Company), Boeing Airplane Company, manufacturing aircraft in the western United States and United Airlines, which served the air routes.

A week after the Air Mail Act was passed Boeing resigned as chairman and sold his stock in the firm.  However, shortly after his resignation, William Boeing received the coveted Daniel Guggenheim Medal for achievement in the field of aviation.  During World War II, he came out of retirement to act as an advisor to the company to meet the demands of combat aircraft development.  The company he started in 1916 went on to develop such influential aircraft as the B-17 Flying Fortress, B-29 Superfortress, B-47 Stratojet and B-52 Stratofortress.  Boeing produced an equally impressive series of airliners, starting with the Stratoliner in 1939, the world’s pressurized airliner, the jet powered 707, 727, 737, and the Boeing 747, the world’s first Jumbo Jet.  A recent first for Boeing was the successful development and production of the 787 Dreamliner, the first jetliner in service made of carbon-fiber materials.  Boeing is now involved in the space technology sector, in addition to the production of aircraft.  Not bad for someone who made the decision to build his own plane in 1916.



This article is the last of a series about the heroes of aviation.