Accident Summary
On June 3, 2014, about 1055 central daylight time, a Beech H35 airplane, registration N653T, impacted a parking lot following a total loss of engine power near Monroe, Louisiana. The commercial pilot, who was the sole occupant, sustained serious injuries. The airplane was substantially damaged. The flight was conducted under 14 Code of Federal Regulations Part 91 as a maintenance test flight. Visual meteorological conditions prevailed, and the flight operated with a flight plan. The local flight originated from Monroe Regional Airport (KMLU) at about 1020.
Background
The airplane was co-owned by the accident pilot and another pilot. They had acquired the airplane in March 2013. Months before the accident, the airplane was mistakenly fueled with Jet-A by the other pilot. Data from the onboard JPI engine data monitoring (EDM) system recorded that on November 1, 2013, cylinder head temperatures (CHT) increased about 460°F several times during a flight. The airplane landed at KMLU and was repaired. An invoice from the repair facility stated that the fuel tanks were drained and mechanics flushed 5 gallons through the fuel system to clear contamination. The engine was removed, repaired, and reinstalled, and the engine fuel hoses were replaced. Work was completed on June 2, 2014.
Accident Sequence
On the accident day, the airplane departed KMLU for a maintenance test flight flown by the commercial pilot/co-owner. The pilot reported an unspecified fuel malfunction before the engine experienced a total loss of engine power. During the forced landing, the airplane collided with a tree and then impacted a parking lot. The cockpit was distorted and crushed aft. The right wing sustained more damage compared to the left wing; the outboard portion of the right wing was torn outboard of the landing light. The fuselage was wrinkled and distorted.
Post-Accident Examination
At the accident site, fuel was drained from each tank and from a fuel line leading to the engine. The fuel from the engine line was light orange in color, while the fuel from the tanks appeared in color and clarity consistent with 100 low lead fuel. The orange fuel was sent for testing. Gas chromatograph mass spectrometer testing on the orange sample revealed the presence of silicon at 12.9 mg/kg. The certificate of analysis noted that if heavier compounds or polymers were present, they were not seen on the gas chromatograph mass spectrometer.
An examination of the airframe and engine was conducted at a salvage facility. No preimpact anomalies were detected with the airframe or fuel tanks. Fuel lines and fuel screens were clear and unobstructed. The engine examination did not detect any preimpact anomalies. No silica or white powdery deposits were noted in the fuel divider, cylinders, or spark plugs.
Engine Data
Data from the JPI EDM for the accident flight began at an EDM time of 1437:44. At 1517:20 EDM time, the engine's CHTs averaged 373°F and the exhaust gas temperatures (EGTs) averaged 1412°F. Within 6 seconds, the EGTs averaged 780°F and continued to decay. About 2 minutes later, the EDM recorded "NA" values for several parameters. Reliable scientific data does not exist to determine a level of silicon contamination prior to obstruction of an airplane's engine performance.