Cessna 421C Golden Eagle III

While conducting a post maintenance test flight in visual flight rules conditions, the private pilot of the multi-engine airplane reported an oil leak to air traffic control. The controller provided vectors for the pilot to enter a right base leg for a landing to the south at the nearest airport, about 7 miles away. The pilot turned toward the airport but indicated that he did not have the airport in sight. Further, while maneuvering toward the airport, the pilot reported that the engine was "dead," and he still did not see the airport. The final radar data point recorded the airplane's position about 3.5 miles west-northwest of the approach end of the runway; the wreckage site was located about 4 miles northeast of the runway, indicating that the pilot flew past the airport rather than turning onto a final approach for landing. The reason that the pilot did not see the runway during the approach to the alternate airport, given that the airplane was operating in visual conditions and the controller was issuing guidance information, could not be determined. Regardless, the pilot did not execute a precautionary landing in a timely manner and lost control of the airplane. Examination of the airplane's left engine revealed that the No. 2 connecting rod was broken. The connecting rod bearings exhibited signs of heat distress and discoloration consistent with a lack of lubrication. The engine's oil pump was intact, and the gears were wet with oil. Based on the available evidence, the engine failure was the result of oil starvation; however, examination could not identify the reason for the starvation.

According to the line service technician who worked for the fixed-base operator (FBO), before taking off for the air ambulance flight with two medical crewmembers and one patient onboard, the pilot verbally asked him to add 40 gallons of fuel to the airplane, but the pilot did not specify the type of fuel. The line service technician drove a fuel truck to the front of the airplane and added 20 gallons of fuel to each of the multiengine airplane's wing tanks. The pilot was present during the refueling and helped the line service technician replace both fuel caps. Shortly after takeoff, a medical crewmember called the company medical dispatcher and reported that they were returning to the airport because smoke was coming from the right engine. Two witnesses reported seeing smoke from the airplane Several other witnesses reported seeing or hearing the impact and then immediately seeing smoke or flames. On-scene evidence showed the airplane was generally eastbound and upright when it impacted terrain. A postimpact fire immediately ensued and consumed most of the airplane. Investigators who arrived at the scene the day following the accident reported clearly detecting the smell of jet fuel. The airplane, which was equipped with two reciprocating engines, should have been serviced with aviation gasoline, and this was noted on labels near the fuel filler ports, which stated "AVGAS ONLY." However, a postaccident review of refueling records, statements from the line service technician, and the on-scene smell of jet fuel are consistent with the airplane having been misfueled with Jet A fuel instead of the required 100LL aviation gasoline, which can result in detonation in the engine and the subsequent loss of engine power. Postaccident examination of the engines revealed internal damage and evidence of detonation. It was the joint responsibility of the line technician and pilot to ensure that the airplane was filled with aviation fuel instead of jet fuel and their failure to do so led to the detonation in the engine and the subsequent loss of power during initial climb.In accordance with voluntary industry standards, the FBO's jet fuel truck should have been equipped with an oversized fuel nozzle; instead, it was equipped with a smaller diameter nozzle, which allowed the nozzle to be inserted into the smaller fuel filler ports on airplanes that used aviation gasoline. The FBO's use of a small nozzle allowed it to be inserted in the accident airplane's filler port and for jet fuel to be inadvertently added to the airplane.

After takeoff from runway 34 at Lyon-Bron Airport, while in initial climb at a height of 200 feet, the twin engine airplane deviated to the left, rolled to the left and then veered to the left with a low rate of climb. Shortly after passing the end of the runway, the airplane lost height then struck the ground and caught fire. The airplane was destroyed by a post crash fire and all four occupants were killed. For unknown reasons, the pilot-in-command was seating in the right seat.

Company personnel reported that, in the weeks before the accident, the airplane's left engine had been experiencing a problem that prevented it from initially producing 100 percent power. The accident pilot and maintenance personnel attempted to correct the discrepancy; however, the discrepancy was not corrected before the accident flight, and company personnel had previously flown flights in the airplane with the known discrepancy. Witnesses reported observing a portion of the takeoff roll, which they described as slower than normal. However, the airplane was subsequently blocked from their view. Examination of the runway environment showed that, during the takeoff roll, the airplane traveled the entire length of the 4,501-ft runway, continued to travel through a 300-ft-long grassy area and a 300- ft-long soybean field, and then impacted the top of 10-ft-tall corn stalks for about 50 ft before it began to climb. About 1/2 mile from the airport, the airplane impacted several trees in a leftwing, nose-low attitude, consistent with the airplane being operated below the minimum controllable airspeed. The main wreckage was consumed by postimpact fire. Postaccident examinations revealed no evidence of mechanical anomalies with the airframe, right engine, or propellers that would have precluded normal operation. Given the left engine's preexisting condition, it is likely that its performance was degraded; however, postimpact damage and fire preluded a determination of the cause of the problem.