On September 2, 2019, at 1120 central daylight time, a Cessna LC41-550FG, N405JA, was substantially damaged when it was involved in an accident near Branson, Missouri. The pilot and two passengers sustained minor injuries. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight.
The pilot stated that he volunteered for the Angel Flight medical transport flight to pick up and fly a child and the child’s mother from Branson Airport (BBG), Branson, Missouri, to Veterans Airport of Southern Illinois (MWA), Marion, Illinois.
The pilot said he arrived at St Louis Downtown Airport (CPS), Cahokia/St Louis, Illinois, about 0930, where the airplane was hangered. He said the engine start and run-up were normal and he departed for BBG.
After arriving at BBG, the airplane was fueled with 100 low lead aviation fuel so that the fuel level in each wing was at the tab, about 40 gallons per tank. Following the preflight inspection, he started the warm engine. The engine started but was running rough. The No. 5 cylinder head temperature was not increasing, but the pilot was able to resolve the discrepancy during the engine run-up.
During the initial climb, the engine began cutting out and surging in a 10 to 15 second cycle. The pilot began a right turn to the airport and turned the vapor suppressor on to clear vapor from the fuel lines; the engine then lost total power. Unable to return to the airport or land on a nearby golf course, the pilot slowed the airplane before impact with trees. The airplane sustained substantial damage, which included structural damage to both wings, the fuselage, and the empennage.
The airplane flight manual stated:
Vapor Suppression – The vapor suppression switch must be turned on in the following situations: Operations above 18,000 ft. If TIT is rising above 1460ºF at full power with the mixture full rich (at any altitude).
Once engine temperatures have stabilized and if the aircraft is below 18,000 ft, the vapor suppression switch may be turned off.
After a hot engine is stopped, the temperature of its various components begins to stabilize. Engine parts with good airflow will cool faster. In some areas, where conduction is high and circulation is low, certain engine parts will increase in temperature. In particular, the fuel injection components (especially the fuel injection pump) will become heat-soaked and may cause the fuel in the system to become vaporized. During subsequent starting attempts the fuel pump will be pumping a combination of fuel and fuel vapor. The vapor suppression switch should also be turned on any time the engine is not running smooth or there is vapor in the lines. Vapor in the lines is most likely to happen in hot weather or altitudes.
Ground operations during high ambient temperature conditions should be kept to a minimum. In situations which involve takeoff delays, or when performing the Before Takeoff Checklist, it is imperative that the airplane is pointed into the wind. During climb out, it may be necessary to climb at a slightly higher than normal airspeed and turn the vapor suppression on. Be sure the mixture is set properly to full rich, and do not operate at maximum power for any longer than necessary. Temperatures should be closely monitored and sufficient airspeed maintained to provide cooling of the engine.
Post-accident examination of the airframe revealed that the cockpit fuel selector was positioned to the left fuel tank. Testing of the fuel selector with air revealed no anomalies in any position. Air was blown through the fuel vent system, which revealed no obstruction to the air flow.
The left fuel tank pick-up screen contained a fibrous material that covered an estimated 15 percent of the screen. The right fuel tank did not contain any debris and the right fuel tank pick-up screen was unobstructed. The gascolator screen did not contain debris. The fuel lines leading to the engine were attached, secure, and did not display evidence of leakage. The auxiliary fuel pump operated when connected to an electrical source. There was no obstruction in the air intake or exhaust systems.
Due to impact damage, an engine run was not performed. Disassembly examination of the engine confirmed engine drive and valve train continuity to the accessory section. There was no failure of the internal engine components or abnormal wear signatures. Magneto-to-engine timing was within specifications. Internal magneto timing of both magnetos was within specifications. All fuel lines were intact, secure, and exhibited no evidence of leakage. There was no contamination/debris within the engine fuel system. Bench testing of the fuel servo and the fuel pump met test specifications. Disassembly of the fuel pump revealed that its internal diaphragm was pliable. Testing of the fuel injectors revealed a normal spray pattern.