Cessna 310B N6605B accident near Columbia, California

Probable cause

The pilot's failure to maintain control during takeoff initial climb for reasons that could not be determined because a postaccident examination of the airframe and engine did not reveal any anomalies that would have precluded normal operation.

NTSB analysis

The airline transport pilot was departing on a cross-country flight in the multi-engine airplane. Shortly after takeoff and during the initial climb, witnesses observed the airplane drift to the left and then descend and collide with terrain off the left side of the departure runway. The airplane came to rest about 3,775 ft from where the takeoff run commenced, and about 300 ft south of the extended centerline of the runway. The majority of the airplane was consumed by postcrash fire. The airplane's estimated ground speed during the last 5 seconds of flight was about 70 knots. It could not be determined whether this speed was above, near, or below the manufacturer's best angle, best rate, or recommended climb speed. The investigation revealed that both engines fuel system had been modified by the removal of the pressure carburetors and replaced with continuous fuel flow injection systems. This modification would require a re-identification on the engine data plate, which was not accomplished, and field approval documentation for the alteration. A search of the airplane's FAA airworthiness file found no records regarding the alteration. Documentation relative to the airplane's revised performance data, which would have been published subsequent to the approval of the fuel injection system modification was also not located in order to determine the effect of airplane performance at the calculated 5,483 foot density altitude at the time of the accident. The propeller strikes found along the debris path and the rotational damage to the blades of both propellers indicated that both engines were developing power at impact. A postaccident examination of the airframe and engine did not reveal any evidence of mechanical anomalies that would have precluded normal operation. The investigation could not determine the reason for the pilot's failure to maintain control of the airplane on takeoff/initial climb.

Text from the NTSB. Open the NTSB docket for WPR16FA152 for the full record.