Investigation: No engine or propeller problems before crash
National Transportation Safety Board's 'factual report' details Feb. 17, 2010, accident that took lives of three Tesla employees
Both the left and right engines and the propeller of the Cessna 310R that took off from the Palo Alto Airport on Feb. 17, 2010, and quickly crashed into an East Palo Alto neighborhood appeared to be working at the time of impact, according to a National Transportation Safety Board report released on Friday, Oct. 7.
The cause of the accident, which claimed the lives of three Tesla Motors employees — the pilot Douglas Bourn, a senior electrical engineer and Santa Clara resident; and passengers Andrew Ingram of Palo Alto, an engineer, and Brian Finn of East Palo Alto, a senior manager — is not outlined in the document, known as a "factual report."
But the report confirms eyewitness accounts of the incident and reveals the findings of inspections of the wreckage by the Federal Aviation Administration and makers of the aircraft parts — Cessna Aircraft Company, Teledyne Continental Motors and McCauley Propellers Inc.
Speculation spread after the crash that a mechanical failure might have caused the plane to veer suddenly and strike an electrical tower next to the Bay in East Palo Alto. Examination of the Cessna's left and right engines, however, showed "no pre-impact mechanical anomalies that would have precluded normal operation," the report states.
In addition, "no indications of propeller failure prior to impact were found. Both propellers were rotating at the time of impact ... and were being operated under conditions of power at the time of impact," the report states.
The manufacturers' inspections were conducted under the supervision of the safety-board investigator Josh Cawthra.
The report confirms that visibility at the airport was 1/8 of a mile due to fog, with wind at 5 knots, at 7:49 a.m., less than five minutes before Bourn took off for the Hawthorne, Calif., airport. Because the runway was not visible, he was instructed to take off at his own risk by the air traffic controller.
"(I) understand," Bourn replied.
Toxicology reports performed on Bourn, 56, by the Federal Aviation Administration showed that he had two drugs in his system — an antihistamine known as diphenhydramine and Metoprolol, which is commonly used to treat high blood pressure.
Bourn had filed a flight plan that indicated the six-seat aircraft would make "a right turn to a heading of 060 degrees within 1 mile of the airport." Instead, radar data used to reconstruct the flight path showed the plane turned 45 degrees to the left shortly after takeoff.
The plane first hit the tower and power lines, located a half-mile northwest of the end of airport runway 31. Debris was strewn over almost a 900-foot path. Parts of the plane crashed into homes, yards and Beech Street. No one on the ground was injured.
The report also states that the Cessna was manufactured in 1977 and had new left and right engines installed in August 2004, after which the plane was flown for about 150 hours.
Bourn, who held a commercial pilot certificate as well as a flight instructor certificate, wrote on his last medical certificate application that he had accumulated 2,900 total flight hours in his aviation career, the report states.
The factual report was written by field investigator Cawthra and is the basis for Cawthra to recommend a probable cause of the accident to the National Transportation Safety Board. The board will review the field investigation reports and vote to adopt, reject or modify the probable-cause determination recommended, according to the agency. The investigation is expected to be completed in mid-November.