The cause of the accident was that the flight crew did not operate the propeller controls correctly, meaning that less drag was created than would have been had the controls been operated correctly.
22.
That crash, the safety board found, was caused by the failure of a worn part in the Hamilton Standard 14RF-9 four-blade propeller control unit, the hub that controls the angle of the blades.
23.
An Embraer 120 that crashed in Georgia in 1991, killing former Sen . John Tower and 22 others, went down after a worn part in a propeller control system, also in its left engine, failed.
24.
;February 20, 1956 : A Capital Airlines Vickers Viscount 744 ( N7404, c / n 90 ) was badly damaged at Chicago Midway International Airport after a hard landing due to a malfunction of the propeller control switches; all 42 on board survived.
25.
FAA records also show seven " service difficulty reports " with the crashed plane, whose registration number was N256AS . After the right engine was shut down in flight in December 1993, the right propeller control unit was found to be defective and was replaced, the report says.
26.
An hour into the flight ( after onboard recording cameras had run out of film ), a leak caused the right-hand propeller controls to lose their effectiveness and the rear propeller subsequently reversed its pitch, disrupting that engine's thrust, which caused the aircraft to yaw hard to the right.
27.
A crash of the same type of aircraft, an Embraer 120, that killed 23 people in Georgia in April 1991, including former Sen . John Tower of Texas, was caused by the failure of a severely worn part in the propeller control unit of the plane, according to an investigation by the National Transportation Safety Board.
