History of Flight
On April 12, 2008, at approximately 1550 Pacific daylight time, a Cessna 310Q, registration N6231Q, experienced a partial loss of engine power while on final approach to Compton Airport in Compton, California. During the attempted forced landing, the airplane descended into residential homes located about half a mile east of runway 25L. The airplane sustained substantial damage, and the commercial certificated pilot and his passenger were seriously injured. Additionally, two occupants in one of the homes were seriously injured.
The flight had originated from Montgomery Field in San Diego, California, at 1506. The pilot reported that earlier in the day, he and his passenger had flown from Hawthorne Municipal Airport to San Diego for a meeting and were returning to Compton. The pilot stated that during preflight at Hawthorne, he visually inspected the main fuel tanks and estimated 25 gallons in each, and the auxiliary tank gauges indicated 10 gallons each. He did not visually check the auxiliary tanks. The flight to San Diego took 49 minutes and did not require use of auxiliary fuel.
Before the return flight from San Diego, the pilot performed a walk-around but did not look into any fuel tanks. The auxiliary tank gauges still indicated 10 gallons each. After takeoff, the pilot climbed to 8,000 feet and began using the auxiliary tanks, which did not run dry. While near Seal Beach, about 13 miles from Compton, the pilot canceled the IFR flight plan, descended to 4,000 feet, and performed the landing checklist, switching fuel selectors to the main tanks.
On final approach to Compton, the left engine began sputtering. The pilot switched back to the auxiliary tanks, but the engine did not restart. He then cross-fed fuel from the right main tank, causing both engines to fail. On short final, the pilot switched the right fuel selector to the right auxiliary tank and raised the landing gear and flaps to reduce drag. The right engine suddenly surged to full power, causing the airplane to roll left. The pilot reduced power, and the airplane, traveling slower than 80 mph, lost speed and stalled.
A Los Angeles County Deputy Sheriff observed the airplane from about half a mile east of the accident site. He noted that the airplane had no audible engine sound during the left base leg turn, then heard a loud sound as if one or both engines restarted, and the airplane passed out of view.
Personnel Information
The 70-year-old pilot held a commercial pilot certificate for airplane single and multiengine land, as well as an instrument rating. He was issued his private pilot certificate in 1970 and his commercial and instrument ratings in 1971 and 1973, respectively. His second-class medical certificate was issued in December 2006 with a requirement to wear corrective lenses.
Aircraft Information
The six-seat, low-wing, retractable-gear Cessna 310Q, serial number 310Q0517, was manufactured in 1972. It was powered by two Teledyne Continental Motors IO-470-VO engines rated at 260 horsepower each. The airplane was maintained under an annual inspection program; the last annual inspection was performed on October 24, 2007, at a total airframe time of 3,858.24 hours and a Hobbs meter reading of 2,392.4 hours. At the time of the accident, the Hobbs meter read 2,409.0 hours.
Fuel for each engine was supplied by a main tank in each wing tip and an auxiliary tank for each engine. Main tanks had a maximum capacity of 51 gallons (50 usable), auxiliary tanks held 20.5 gallons (20 usable), for a total capacity of 143 gallons with 3 gallons unusable. According to the Owner's Manual, at 64 to 66 percent power and 2,300 to 2,450 rpm between 5,000 and 10,000 feet, fuel consumption was 24.0 to 24.6 gallons per hour. The minimum single-engine control speed (Vmc) was 86 mph indicated.
Meteorological Information
At 1453, Hawthorne Municipal Airport, about 6 miles from the accident site, reported clear skies, visibility 10 miles, wind from 280 degrees at 8 knots, altimeter 29.99 inches Hg, and temperature 33°C.
Wreckage and Impact Information
The airplane impacted several structures. The initial point of impact was with a metal-framed outdoor patio awning in the backyard of 526 W. Cypress Street. The airplane then struck a concrete block wall, and the right wing fuel tank was crushed and severed. The main wreckage came to rest nose-down with the empennage nearly vertical in the backyard of 530 W. Cypress Street. The left wing penetrated the eastern wall of a two-story residence at 534 W. Cypress Street. The wreckage lay about 2,100 feet east of runway 25L's displaced threshold and 100 feet south of the extended centerline.
Responding firemen detected a fuel odor, but examination of breached fuel tanks and surroundings revealed no fuel residue. The landing gear and flaps were retracted. The left engine fuel selector valve handle was in the cross-feed position (drawing from the right main), and the right engine selector was between right auxiliary and left main. Fuel caps were found on all four tanks. No preimpact mechanical malfunction was found in the airframe or engines; both engines produced compression, and spark plugs showed normal wear. Propellers were not feathered.
Additional Information
The pilot estimated that upon departure from San Diego, the airplane contained about 30 gallons of fuel and would burn about 25 gallons per hour. He reported using approximately 65 percent power during the accident flight.