Accident Description
While descending for landing in Baton Rouge, the captain actively moved the power levers from the flight idle gate into the beta range for reasons that could not be determined. This action caused the propellers and engines to experience extreme overspeed. The flight crew was forced to perform a power-off emergency landing at night. During the landing, the airplane ran off the end of a 5,000-foot runway.
Design and Certification Issues
The design and certification of the power levers met the existing regulatory requirements. However, those requirements were found to be inadequate because they permitted a design that did not prevent movement of the power levers into the beta range during flight. This design flaw was identified as a contributing factor to the occurrence.
Industry and Regulatory Response
The airframe and engine industry, the Federal Aviation Administration, and certification authorities from other countries were slow to react to several previous in-flight beta occurrences that had led to serious incidents and accidents. The delayed response allowed the design deficiency to persist, despite prior warnings.