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On January 26, 2007, about 1145 Pacific standard time, a JIHLAVAN KP-5 light sport aircraft (LSA), N215KP, experienced a partial loss of engine power and collided with a dirt berm during the precautionary landing in Moorpark, California. The airplane sustained substantial damage during the accident sequence. The pilot/owner was operating the airplane under the provisions of 14 CFR Part 91. The commercial pilot, the sole occupant, sustained minor injuries. The local personal flight departed Santa Paula Airport, Santa Paula, California, about 1100. Visual meteorological conditions prevailed, and a flight plan had not been filed.
The pilot reported that after departing Santa Paula he planned on maneuvering the airplane around a construction site that a family member owned. While maneuvering about 1,500 feet mean sea level (msl), the airplane's engine surged and experienced a partial loss of power. The pilot opted to perform an off-airport landing in an open field below. The airplane touched down on the field, which was comprised mostly of loose dirt. The brakes were somewhat ineffective due to the loose terrain, and the airplane collided with a dirt berm located at the end of the field.
Several construction workers witnessed the accident and submitted written accounts of their observations. One witness reported that the airplane briefly touched down on the flat dirt and departed. The airplane then flew back and touched down again, crashing into a slope during the landing. Another witness stated that the airplane was circling above his location. The airplane landed and collided with a ditch.
The National Transportation Safety Board investigator-in-charge (IIC) reviewed files on the accident airplane maintained by the Federal Aviation Administration. The JIHLAVAN KP-5, single engine airplane, serial number 5111129K, was manufactured in 2005. It was issued an airworthiness certificate in the light sport category on October 27, 2005. Despite numerous attempts, no engine logbooks were located. According to the pilot, the airframe and engine had accumulated 98.2 flight hours prior to the accident.
The airplane had a Rotax 912ULS engine (tractor-configuration), serial number 5645163. The engine's intake air was drawn from inside the cowling (adjacent to the lower firewall) and routed through an air filter. The intake air was then directed into a sole airbox that fed both carburetors.
The engine was outfitted with two Bing "Constant Compression" carburetors. These variable venturi carburetors were not equipped with butterfly valves; rather, they utilized moving slides to regulate airflow. This configuration enabled the venturi area to change with the throttle setting.
The airplane did not have carburetor heat, nor did it have an alternate air source.
A routine aviation weather report (METAR) for Camarillo, California (located about 12 miles southwest of the accident site), was issued at 1155. It stated: skies clear; visibility 10 miles; winds from 230 degrees at 5 knots; temperature 62 degrees Fahrenheit; dew point 46 degrees Fahrenheit; and an altimeter of 30.03 inHg.
The temperatures were applied to an industry Carburetor Icing Probability Chart revealing that the recorded temperatures were within the "serious icing at glide power" portion of the chart.
TESTS AND RESEARCH
Following recovery, the Safety Board IIC examined the airplane at the maintenance facilities of Ray's Aviation, Santa Paula, on February 16, 2007.
The airplane was separated into three major components for the purpose of recovery. The wreckage consisted of the left and right wing, and main airframe (with the engine attached at the mounts). Recovery personnel detached both wings from their respective inboard roots, leaving the filler necks exposed from the inboard fuel tank.
The Safety Board IIC established control continuity from the control rod ends at the wing sections (disconnected by recovery personnel) to the flap and aileron control surfaces. Continuity was additionally established from the rod ends at the inboard wing sections to the cockpit control stick. Continuity was established from the cockpit controls to the rudder and elevator control surfaces. Both wings contained numerous dimples of damaged skin. The left wing was gouged where the rib was damaged about 11 feet 2 inches outboard; the puncture stretched about 3 inches aft.
The engine remained intact with the cowling secured. The engine had incurred visible external damage consisting of an upward crushing to the muffler and connected exhaust stacks, as well as the water cooler. A teardown examination was preformed during which, all cylinders, pistons, and accessories were removed and inspected.
Continuity was established for both the throttle and choke control cables and manipulation of the controls both forward and aft moved the cables from stop to stop.
The spark plugs were secure at each position with their respective spark plug leads attached. The plugs were removed, examined, and photographed. The spark plug electrodes remained mechanically undamaged, and were gray with a yellow coloration in the center. The top spark plugs, attached to their respective leads, were positioned adjacent to the crankcase while the engine was cranked with the master switch activated. Spark was obtained from each spark plug.
The crankshaft was rotated by turning a propeller blade still affixed to the spinner assembly; it was free and easy to rotate in both directions. Compression was observed in all four cylinders, with air felt to egress through the top spark plug bores during rotation. The complete valve train was observed to operate in proper order, with lift action observed at each rocker assembly. Clean, uncontaminated oil was observed at all four rockerbox areas. Mechanical continuity was established throughout the rotating group and valve train during the rotation of the crankshaft.
All cylinders were removed, revealing no evidence of foreign object ingestion or detonation. All valves were intact and the internal cylinder domes and piston crowns exhibited similar combustion deposits and coloration. The camshaft was observed to rotate freely and the visible lobes were egg-shaped with no evidence of corrosion or pitting.
The internal ducts of the exhaust displayed deposits of white powder. The oil filter was removed and cut open; there was no evidence of residue or contamination inside.
The fuel selector was selected in the "off" position, which the pilot indicated he had selected after the accident. The fuel selector was removed and examined. It appeared to function normally by allowing air pressure to pass the switch unit when in the "on" position and closing air from passing when in the "off" position. Air pressure was routed from both the right and left fuel selector lines (where they attached to the fuel selector). The air was felt egressing the respective filler neck in the fuel tank located in the inboard wing.
The electrically driven fuel pump, located just aft of the fuel selector, was removed and rigged to an electrical source. It produced suction at its inlet when electrical power was applied. Removal of the fuel filter inside the pump revealed that is had trace amounts of debris in the tip, which had the consistency of dirt. The engine driven fuel pump was removed and engaged by applying a downward force, which resulted in the unit rapidly ejecting fluid that was consistent in odor with automobile gasoline.
Removal of both the right and left Bing carburetors revealed that the bowls were full with a fluid consistent in appearance and odor to that of automobile gasoline. The floats were intact and buoyant. The diaphragms on top of the bowl units were pliable and the springs were intact.
There was no evidence of premishap mechanical malfunctions observed during the examination of the engine and airframe.
Light Sport Aircraft (LSA)
The creation of the LSA transpired from the FAA tasking the general aviation industry to develop new regulations for design, company-delegated certification, and quality control for a proposed new segment of light aviation. Accordingly, the FAA mandated in the LSA rule, that consensus standards be developed to govern the production of light sport aircraft. In response, the predominant members within different facets of the industry together developed a set of consensus standards. The FAA engaged the American Society for Testing and Materials (ASTM) to assist the light sport aircraft community in the development of those standards.
The Light Aircraft Manufacturers Association (LAMA) performs audits of manufacturers to verify they are properly following the ASTM Standards. A representative from LAMA stated that there are several areas within the standards that address carburetor icing. The Standard Practice for Design and Manufacture of Reciprocating Spark Ignition Engines for Light Sport Aircraft, section 5.7.1, Induction System Icing, states that "the fuel and air passages must be designed to minimize the accretion of ice." The Standard Specification for Design and Performance of a Light Sport Airplane, section 7.5, Induction System, requires that "the engine air induction system shall be designed to minimize the potential of carburetor icing."
In contrast, FAA certificated airplanes are required by FAR 23 to be equipped with induction system icing protection. In pertinent part, the regulation states
"(a) Reciprocating engines. Each reciprocating engine air induction system must have means to prevent and eliminate icing. Unless this is done by other means, it must be shown that, in air free of visible moisture at a temperature of 30° F -.
(1) Each airplane with sea level engines using conventional venturi carburetors has a preheater that can provide a heat rise of 90 degrees Fahrenheit with the engines at 75 percent of maximum continuous power;
(2) Each airplane with altitude engines using conventional venturi carburetors has a preheater that can provide a heat rise of 120 degrees Fahrenheit with the engines at 75 percent of maximum continuous power;
(3) Each airplane with altitude engines using fuel metering device tending to prevent icing has a preheater that, with the engines at 60 percent of maximum continuous power, can provide a heat rise of -
(i) 100 degrees Fahrenheit; or
(ii) 40 degrees Fahrenheit, if a fluid deicing system meeting the requirements of 23.1095 through 23.1099 is installed;
(4) Each airplane with sea level engine(s) using fuel metering device tending to prevent icing has a sheltered alternate source of air with a preheat of not less than 60 degrees Fahrenheit with the engines at 75 percent of maximum continuous power;"
At the request of the Safety Board IIC, the airplane manufacturer, JIHLAVAN airplanes, s.r.o, located in the Czech Republic, performed an authentication testing of temperatures inside the engine cowling with respect to risk of carburetor icing during flight.
Temperature probes were placed in the following three locations: the intake just prior to entering carburetor; the entrance of intake filter; the upper area of engine cowling. The airplane used during the testing was the same standard configuration as the accident airplane. The testing was conducted with the outside temperature varying between 32 and 37 degrees Fahrenheit with a humidity of 90 percent. These conditions applied to the aforementioned icing probability chart were in the category of "serious icing at cruise power." During the testing, operating temperatures at all probes remained between 77 and 95 degrees.
The manufacturer concluded that even if the airplane enters carburetor icing conditions, the air within the system (intake) would be sufficiently heated prior to entering the carburetor. The complete report with accompanying pictures is contained in the public docket for this accident.