Flight History
On February 27, 2017, about 1641 Pacific standard time, a Cessna T310Q, N1246G, was destroyed when it collided with multiple residences after departure from Riverside Municipal Airport (RAL), Riverside, California. The airline transport pilot and three passengers were fatally injured; one passenger received serious injuries. The airplane was operated under Part 91 on an instrument flight rules (IFR) flight plan to Norman Y. Mineta San Jose International Airport (SJC).
According to the surviving passenger, the group had flown from SJC to RAL on February 24. On February 25, the pilot had the airplane fully refueled and purchased charts. On the accident day, the group returned to RAL about 1200. After boarding, the pilot started the right engine but could not start the left engine. They deplaned and later attempted departure again but returned to the terminal. The pilot then filed an IFR flight plan with help from a flight school employee.
After a third boarding, the pilot received an IFR clearance at 1602 and requested taxi at 1615, with several communication difficulties. At 1632, the pilot read back the obstacle departure procedure correctly and was cleared for takeoff at 1638. An airport employee observed an uneventful liftoff, then a left turn into clouds (ceiling 600 ft). Radar data showed the airplane at 1639:50 at 1,100 ft msl, turning to 070° at 1640:08. Radar contact was lost at 1640:27 at 1,700 ft msl (about 900 ft agl). No distress calls were received.
The surviving passenger recalled shaking after takeoff, then violent vibration and a horn sound she later identified as a stall warning horn. The airplane descended rapidly in a slight left wing-low attitude, as captured by surveillance video, and disappeared behind a residence, with fire and smoke appearing immediately.
Pilot Information
The 83-year-old pilot held an airline transport pilot certificate with single-engine land and commercial multi-engine land ratings, and a flight instructor certificate. His most recent second-class medical certificate (October 13, 2016) required corrective lenses. He reported 9,600 total flight hours, with 21 hours in the previous 6 months. His recent instrument flight experience and instrument competency check could not be determined.
Aircraft Information
The 1974 Cessna T310Q (N1246G) was powered by two Continental TSIO-520 J engines. The most recent annual inspection was completed on February 1, 2017, at 4,830 hours total time; both engines had about 1,265.1 hours since overhaul. The airplane had main wing tanks (102 gallons total) and auxiliary wingtip tanks (63 gallons total). On February 25, the airplane was topped off with 54 gallons of 100LL aviation gasoline; a fuel sample showed no contamination.
A weight and balance estimate using occupant weights from autopsy reports and the surviving passenger, and recovered baggage, computed a total weight of 5,812 lbs, 312 lbs over the maximum gross weight of 5,500 lbs. The computed center of gravity (CG) of 36.82 inches was forward of the forward limit of 38.67 inches at gross weight. According to the FAA Airplane Flying Handbook, performance outside the envelope cannot be predicted. The stall speed per the pilot's operating handbook was 75 knots (no bank) and 78 knots (20° bank).
Weather Conditions
At the time of the accident, instrument meteorological conditions prevailed at RAL. The 1637 weather observation reported calm wind, visibility 2 miles in light rain and mist, scattered clouds at 600 ft agl, overcast ceiling at 4,200 ft agl, temperature/dew point 11°C, and altimeter 29.82 inHg. The pilot had filed an IFR flight plan and was in possession of adverse weather information from a personal source.
Wreckage and Examination
The accident site was located about 1 nm northeast of RAL in a residential area. The initial impact point was identified by a broken chimney on a house. Multiple fragments were found along a debris path oriented on a heading of about 345° magnetic. Postcrash fire consumed one house and the main wreckage, which included the cabin, both engines, portions of wings, and the left propeller.
Flight control continuity was established with overload separations. The left engine's crankshaft rotated freely; cylinder No. 6 had a crushed exhaust valve but no internal deformation. The right engine's crankshaft rotated freely; its oil sump contained sludge with magnetic particles. Both propellers displayed signatures consistent with medium rotational energy absorption and blades near the low pitch stop at impact.
Examination of the cabin heater assembly showed thermal damage but no leaks when pressurized.
Medical Findings
An autopsy on the pilot listed cause of death as multiple blunt impact injuries. The pilot had an enlarged heart with significant coronary artery narrowing (70% of left anterior descending and right coronary arteries, 40% of left circumflex). Toxicology tests detected no drugs of abuse, alcohol, or carbon monoxide in the pilot. The front right seat passenger had no carbon monoxide detected; another passenger tested 21% carbon monoxide, reason unknown.
Additional Findings
Laboratory examination of oil sludge from the right engine detected lead and bromine, consistent with typical deposits from 100LL aviation gasoline.