Incident Overview
After completion of an annual inspection, the aircraft owner elected to conduct a maintenance test flight. During the flight, the pilot intentionally shut down the right engine, then feathered and unfeathered the propeller, and successfully restarted the engine by allowing the propeller to windmill.
Sequence of Events
The pilot then followed the same procedure with the left engine and propeller. However, the propeller failed to unfeather, and he could not restart the left engine. The pilot returned to the airport with one engine operating. During pattern entry, he attempted to extend the landing gear, but the landing gear did not extend. The pilot initiated a go-around. The aircraft did not climb and began to lose altitude. Eventually, it collided with the ground off the airport during an unarrested descent.
Landing Gear and Hydraulic System
The landing gear extension and retraction system was hydraulic and powered by a pump on the left engine. The flight manual provided two alternate means of emergency gear extension, neither of which the pilot attempted on the first landing approach.