CESSNA 310J — Inola, OK

What happened

The airplane’s most recent flight was about 9 months before the accident, and the pilot was flying the airplane on a ferry permit to another location to complete an overdue annual inspection. Before the accident flight, the airplane’s fuel tanks were topped off, and the pilot completed a preflight inspection that took about 1 hour. After taxiing to the runway area, the pilot returned to the ramp due to an unknown right engine issue.

Following an extended engine run-up, the pilot taxied back to the runway and departed. Flight data showed that the airplane climbed to 5,800 ft mean sea level on an easterly heading, and about 1 minute before the accident, the airplane made a left turn to the north and began a rapid descent. For the last 23 seconds of the flight, the descent rate increased from about 1,000 to 30,000 ft per minute, and the ground speed varied between 151 and 198 knots. During the rapid descent and just before impact, the empennage and outboard wing sections separated. There were no emergency communications from the pilot and no witnesses to the accident.

Distribution of the wreckage and damage signatures observed during postaccident examination were indicative of an in-flight breakup at low altitude due to the exceedance of structure design limitations. The left cockpit propeller control lever was found in the feathered position. Both propellers displayed indications consistent with low power; however, exact engine power levels could not be determined. In addition, both propellers had impact signature markings indicating blade positions at or near feather blade angles during the impact sequence. Although the airframe and engine examinations revealed no evidence of mechanical malfunctions or failures, the extensive impact damage precluded a functional examination of the flight controls. Investigators were unable to determine the reason for the loss of control and rapid descent based on the available evidence.

The airframe and engine examinations revealed no evidence of mechanical malfunctions or failures that would have precluded normal operation.

Although the pilot tested positive for gabapentin, which is potentially sedating, tolerance to the sedating effects build quickly, and the pilot had likely been using the medication for some time. Thus, it is unlikely that any effects from the pilot’s use of gabapentin contributed to the circumstances of the accident.

An editorial "what led to it / how to avoid it" analysis for this accident is generated separately and will appear here.