CEN15LA018

The pilot reported that he was returning from an air race competition and that, about 15 minutes into the flight, he heard a "thump" and thought the airplane had struck a bird. The pilot then heard a second "thump" along with a "rattle and vibration," so he found a place to make a forced landing. While preparing to land, he heard an "explosion" and then saw flames by his left foot and black smoke fill the cockpit. The pilot made a forced landing to a field and exited the airplane before it was destroyed by fire. Postaccident examination of the engine revealed that the No. 3 cylinder's exhaust rocker cover was present but that it was only installed on the cylinder by one screw. The other four screws were missing. The No. 3 cylinder's intake rocker cover and aft rocker arm bolt were missing. The forward rocker arm bolt was installed but loose, and visible rubbing was observed on the boss where the missing bolt was supposed to be installed. According to the engine manufacturer, if a rocker cover is not installed, the engine will port out most of its oil is several minutes. Therefore, the missing rocker cover likely resulted in the engine losing a significant amount of oil during the flight, which led to a catastrophic and uncontained engine failure. It is also likely that, when the crankcase was breached, the fuel lines and the electronic fuel transducer were compromised, which resulted in the subsequent in-flight fire. The No. 3 cylinder intake rocker cover was not located at the accident site, and the pilot reported that he did not know why the rocker cover and aft rocker arm bolt were not installed or why the exhaust rocker cover was only partially installed. He said that the engine performed great during the air race and that he did not perform engine maintenance after the race.

On October 18, 2014, about 1815 central daylight time, N550AC, an experimental-home built Viguie Lancair Legacy, was destroyed by post-impact fire after the pilot made a forced landing to a field near Livingston, Texas. The air transport pilot sustained serious injuries. The airplane was registered to and operated by the pilot. A visual flight rules flight plan was filed for the flight that departed Jasper County Airport (JAS), Jasper, Texas, about 1815 and was destined for a private airstrip in Buchanan Dam, Texas. Visual meteorological conditions prevailed for the personal flight conducted under the provision of 14 Code of Federal Regulations (CFR) Part 91. A witness was standing out in his pasture when he first heard and saw the airplane. He said the engine was running rough and there were flames under the engine. The airplane made a descending turn and prepared to land in a pasture across the road. As the witness responded to help the pilot, he heard a "loud crunch" and saw a "fireball." When he got to the field, the pilot was walking toward him. The pilot stated he was returning from an air race competition and had just leveled off at 8,500 feet when he heard a "thump", about 15 minutes into the flight. The pilot thought he struck a bird and told air traffic control that he needed to land. The pilot then heard a second thump along with a "rattle and vibration" and immediately found a place to make a forced landing. While preparing to land, there was a third "explosion." The pilot said that this was when he saw a fire near his left foot and black smoke started to fill up the cockpit. The pilot declared an emergency, secured the engine, unlatched the canopy, and made a forced landing to a field. He said the landing was hard and the instrument panel flexed downward and trapped his feet. Once the airplane came to a stop, he realized his shirt was on fire as he struggled to free his legs. The pilot was finally able to exit the burning wreckage and rolled on the ground to put the flames out. He then got up and was met by the witness, who stayed with him until help arrived. An inspector with the Federal Aviation Administration (FAA) performed an on-scene examination of the airplane. The inspector stated that the airplane landed hard then slid for several hundred feet before it came to rest and was consumed by fire. The propeller and the engine cowling separated from the airplane. The inspector also stated that when he looked at the engine, the #3 cylinder's intake rocker-cover and the aft bolt for the rocker- arm were missing. The rocker-cover for the #3 exhaust valve was attached to the engine by one screw. The inspector said he looked for the #3 cylinder's intake rocker-cover, but was unable to find it at the accident site. According to a representative of the company that recovered the airplane and engine, they were aware of the missing rocker-cover. They had searched for the cover but it was never found. The engine was examined on November 14,2014, under the supervision of the National Transportation Safety Board Investigator-in-Charge (NTSB IIC). Also present for the examination was a representative of Continental Motors Incorporated and Lancair. The examination revealed that the engine sustained fire and impact damage, with the most extensive fire damage to the top and aft-left side. The interior section of the composite engine cowling exhibited oil splatter and fire damage. The bottom left side of the cowling was consumed by fire. The crankshaft could not be rotated due to fire and impact damage and there were two large holes in both sections of the crankcase above the #2, #3, and #4 cylinders. The #3 cylinder intake rocker-cover and the aft bolt for the rocker-arm were missing. The forward bolt was in place and loose. Rubbing damage was visible on the boss where the bolt was missing. The #3 cylinder exhaust rocker-cover was not damaged and was only attached to the engine by its lower aft screw. The other four screws were missing. The rocker covers for the remaining cylinders were not damaged and were tightly secured to the engine. The engine was equipped with fuel metering unit and fuel manifold. The fuel metering unit sustained extensive heat damage and was partially melted. The output line for the metering unit was separated from impact and the throttle was in the "idle" position and the mixture was in the "cut-off" position. The fuel manifold was still installed on the top of the engine but was fire damaged. The unit was disassembled and the spring was in place, but the rubber diaphragm was destroyed from heat damage. The plunger could not be removed due to heat damage. The fuel nozzles sustained heat damage and were all blocked except for the #5 nozzle, which was partially blocked. The engine had an electronic Floscan fuel transducer installed in the fuel line between the fuel pump and metering unit. The transducer was installed over the top of the engine and sustained extensive heat damage and melting. The engine was equipped with an electronic ignition system, which sustained extensive heat damage. When the engine was disassembled, the #2, #3, and #4 connecting rods were found separated from their respective journals on the crankshaft. The oil sump sustained fire and impact damage and contained numerous metal pieces and particles. This was also true for the oil filter. The #1, #2, and #3 main oil journals were dry and heat discolored, consistent with oil starvation. The #2 and #4 pistons were stuck in their respective cylinder due to heat and impact damage. The #3 piston sustained heavy fire/impact damage and most of the skirt was broken away. The #1 cylinder could not be removed. The #5 and #6 were removed from their respective cylinder and exhibited light deposits on the piston heads. The pilot said he did not know how or why the #3 cylinder intake rocker-cover and aft rocker-arm bolt were not installed and did not have an explanation as to why the exhaust rocker-coverwas partially installed. He said the engine ran great during the air race and he did not remove the cowling and perform engine work after the race. The pilot stated the logbooks were in the airplane at the time of the accident. However, the last condition inspection on the engine was conducted on August 27, 2014, at a total engine time of 646.8 hours. According to Continental Motors, it would have taken several minutes for the engine to port most of its oil out without the rocker cover installed. .