lotnictwo: Lockheed Electra wing failure investigation

Evidence: 100 • authority: 72

Following two fatal accidents in 1959 and 1960 in the United States involving the Lockheed L-188 Electra turboprop airliner, the Federal Aviation Agency (FAA) and Lockheed launched an extensive investigation into the accidents' causes. Braniff Airways Flight 542 and Northwest Airlines Flight 710, both operating with relatively new, high-speed Lockheed Electra aircraft, had crashed six months apart after suffering in-flight breakups where in each case, at least one of the wings had separated from the fuselage. Investigators working on the first accident had not yet managed to determine the cause of the wing failure when the second accident occurred, in an almost identical manner. The FAA imp…

Evidence: 54 • authority: 72

Braniff Airways Flight 542 was a scheduled flight between Houston International Airport and Idlewild Airport in New York City. On September 29, 1959, while en route to a scheduled stop at Dallas Love Field, the Lockheed L-188 Electra operating the flight broke apart in mid-air without warning, about four miles (six kilometers) southeast of Buffalo, Texas. Eyewitnesses who saw the crash said they saw an explosion in the air, and then the aircraft plummeted to the ground. The left wing separated from the plane close to where it attaches to the fuselage and landed more than a mile (two kilometers) from the main crash site. The explosion and resulting crash left no survivors. The aircraft was a…

Evidence: 48 • authority: 72

Northwest Airlines Flight 710 was a scheduled flight between Minneapolis, Minnesota and Miami, Florida, with a stop in Chicago. On March 17, 1960, the six-month-old Lockheed L-188 Electra operating the flight broke up in midair in southern Indiana, near Cannelton, killing all 63 people on board. After unexpectedly encountering clear-air turbulence at 18,000 feet (5,500 m), the aircraft's right wing and part of the left wing separated, causing the fuselage to plummet and impact the ground at a nearly 90-degree angle, leaving a deep crater. Portions of the wings landed up to four miles (six kilometers) away. The in-flight breakup of the Electra closely resembled the September 1959 crash of Br…

Evidence: 36 • authority: 72

The Lockheed Electra Action Program (LEAP) was the name of a program by Lockheed Corporation between 1960 and 1961 that was responsible for the design and deployment of modifications to the Lockheed L-188 Electra aircraft to resolve a critical fault that had caused two fatal airline crashes. The investigations of the crashes of Braniff Airways Flight 542 and Northwest Airlines Flight 710 revealed that a previously unanticipated phenomenon called "whirl mode wing flutter" could occur in certain circumstances, and when it did, it would lead to a rapid failure of the wings of the aircraft. Lockheed implemented LEAP to design the needed structural changes to the aircraft to prevent whirl mode w…

Evidence: 36 • authority: 72

The Lockheed L-188 Electra is an American turboprop airliner built by Lockheed. First flown in 1957, it was the first large turboprop airliner built in the United States. With its fairly high power-to-weight ratio, huge propellers and very short wings resulting in the majority of the wingspan being enveloped in propwash, large Fowler flaps which significantly increased effective wing area when extended, and four-engined design, the airplane had airfield performance capabilities unmatched by many jet transport aircraft even today—particularly on short runways and high altitude airfields. Initial sales were good, but after two fatal crashes that led to expensive modifications to fix a design…