Accident Summary
An airplane completed its annual inspection on the same day as the accident and was on its first flight after the inspection. As the airplane departed from runway 05 at Naples Municipal Airport, witnesses reported that the engine ceased operating and that the propeller was rotating slowly or had stopped. The airplane then entered a steep turn, followed by an abrupt and uncontrolled nose-low descent, and subsequently impacted the ground. The wreckage came to rest in a nose-low, near-vertical position, suspended by its tail section on a fence and trees along the eastern airport perimeter. The airplane sustained substantial damage. The pilot and two passengers onboard received fatal injuries.
Investigation Findings
Postaccident examination of the airframe, flight controls, and engine revealed no mechanical failure or malfunction. The flaps were set to 10 degrees, and the propeller showed little or no evidence of rotation at impact.
Toxicological Analysis
The FAA Toxicology Laboratory analyzed specimens from the pilot. Diphenhydramine (Benadryl), an over-the-counter antihistamine with sedative side effects, was found in urine and at a concentration of 0.139 µg/ml in blood. Published research notes that a maximal over-the-counter dose of diphenhydramine can impair driving performance more than a 0.10% blood alcohol level on some measures. The detected level was consistent with recent use exceeding a typical maximum single dose.
Probable Cause
The National Transportation Safety Board determined the probable cause was the pilot's failure to maintain airspeed above the stall speed while maneuvering to land after the engine ceased operating for undetermined reasons, which resulted in a stall/spin, uncontrolled descent, and impact with the ground.