Pipistrel SINUS N269PW accident near Haverhill, Massachusetts

Probable cause

The pilot's failure to utilize the proper procedure and unfeather the motorized glider’s propeller prior to an in-flight engine restart, resulting in a lack of thrust and subsequent forced landing.

NTSB analysis

The pilot departed in his motorized glider, climbed to 3,500 ft, then turned off the engine and feathered the two-bladed propeller once he reached the area where he wanted to soar. Since weather conditions were not conducive to soaring, he attempted to return to the airport. In preparation to land he said he restarted the engine without using the glider's documented procedures. The engine started but was not producing the expected power. The pilot thought he had a fuel problem and was not aware that the propeller was still in a feathered condition. Although the engine was operating normally, the feathered propeller was unable to produce the thrust needed to maintain altitude. The pilot subsequently made a forced landing and the airplane impacted a fence about 1.5 miles short of the runway. The glider sustained substantial damage.

Postaccident examination of the glider revealed that both propeller blades and the propeller control knob were in the feathered position. Examination of the engine and airplane revealed no mechanical deficiencies that would have precluded normal operation at the time of impact.

Text from the NTSB. Open the NTSB docket for ERA19LA214 for the full record.