SNIPPETS OF HISTORY: ‘ United Airlines Douglas DC-6 Crashed & Investigation Showed Requirement to Prevent Reversal of Blades ‘

#AceHistoryNews – NEW YORK: On April 4, 1955, a United Airlines Douglas DC-6 crashed (similar aircraft pictured) shortly after taking off from Long Island MacArthur Airport, in the U.S. community of Ronkonkoma in Islip, New York.

"UnitedDC-6taxiOak52 (4412118579)" by Bill Larkins – UnitedDC-6taxiOak52Uploaded by russavia. Licensed under CC BY-SA 2.0 via Wikimedia Commons –

The aircraft, named Mainliner Idaho, began banking to the right after
takeoff, then swerved 90 degrees, nosedived, and hit the ground, killing all three crew-members.

An investigation found that they had been simulating an engine failure on an instrument rating check flight, but had pulled back the throttle lever for engine No. 4 too far, causing the propeller blades to reverse, a feature normally used only to slow the aircraft during landing.

They had also failed to raise a metal flag in the cockpit that would have allowed the blades to return to the proper position during flight.

Investigators from the Civil Aeronautics Board concluded that crew lost control of the aircraft when they applied full power to No. 4 engine, and that the sudden bank and dive left the crew little time to recover from their mistake.

After the investigation, the Civil Aeronautics Administration issued an Airworthiness Directive ordering all United Douglas DC-6 and DC-6B aircraft to be fitted with a manual device to prevent the inadvertent reversal of the blades.

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