Lockheed L-188 Electra

The Lockheed L-188 Electra was the first and only USA-built large turboprop airliner and was developed to meet an American Airlines requirement of a domestic short to medium range airliner seating 75 to 100 passengers. The Electra first flew on 6 December 1957 and entered service with Eastern Airlines on 12 January 1959. The idea was to deliver almost-jet performance at much lower operating costs.
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The Lockheed Electra is a four-engined turboprop aicraft with a fuselage with circular cross-section. Lockheed built two basic versions of the Electra. The basic production aircraft was the L-188A and this was the most sold version. The L-188C had greater fuel capacity and higher weights, resulting in improved payload range performance. This version entered service with KLM in 1959.
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A number of crashes in 1959 and 1960 resulted in some cancellations of orders. Aircraft of American Airlines, Braniff and Northwest Orient broke up in flight, killing all passengers and crew on board. In spite of calls for grounding the Electra, the FAA chose for imposing speed restrictions. The cause was a vibration problem, weakening the engine mounts resulting in the breaking away of the complete wing. The problem was found soon and Lockheed had to undertake significant modifications to strengthen nacelle mountings and wing structure. In 1961 the speed restrictions were lifted.
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The Lockheed Electra didn't recover from this major blow, however, and in 1961 production ended after only 170 aircraft had been built.
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Lockheed developed two versions of the Electra. The standard model was the L-188A, of which 114 were built. The L-188C was an international version with larger fuel tanks and more range. It was ordered by Northwest and the biggest European customer became KLM with an order for twelve aircraft. A proposed L-188B, with a navigator instead of an observer, was never built.
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Most Electras were configured to freighters. Only a very small number of the Lockheed Electra is still in active service. The L-188 was the second aircraft developed by Lockheed wearing the name 'Electra'. The first Electra was the L-10, an all-metal, twin-engine airliner developed in the 1930s and competing with the Douglas DC-2 and the Boeing 247.
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