Incident Overview
During climb, one of the four propeller blades on the number two engine separated from the propeller hub. The separation damaged another propeller blade and the fuselage. Shortly thereafter, the engine shut down.
Effects of Unbalance
The rotational unbalance caused by the blade separation was accompanied by extreme vibration. This resulted in distortion and damage to the engine/cowl assembly and the wing. The upper portion of the engine cowl was deflected upward over the wing at an angle of about 30 degrees, which led to distortion of airflow, buffeting, and degradation of roll control.
Emergency Landing
Due to excessive drag, maximum power was required on the number one engine in order to control the rate of descent and land successfully.
Metallurgical Findings
A metallurgical examination disclosed evidence of fatigue cracking of the propeller hub arm.