ERA15FA208

A partial loss of engine power due to contamination in the fuel manifold, which resulted in a collision with terrain shortly after takeoff.

Several days before the accident flight, the commercial pilot told his mechanic and flight instructor that the airplane had not been climbing well. The pilot had completed an engine run-up and subsequent test flight, and found no anomalies with the airplane. The accident flight was the second leg of a cross-country trip that originated earlier in the morning. During the accident takeoff, the pilot stated to air traffic control that the airplane was having trouble climbing. The airplane subsequently collided with terrain about 2 miles from the runway. Postaccident testing of the fuel manifold showed that it was not operating normally and was contaminated with debris. The composition of debris and its origin could not be determined, but it was likely that the debris moved within the fuel manifold during operation and resulted in fluctuating power indications. Examination of the engine did not reveal any mechanical anomalies. Although the airplane was likely loaded 24 pounds in excess of its maximum gross weight, takeoff distance calculations showed that sufficient runway was available when loaded at the maximum gross weight for the departure and climb, assuming nominal performance of the airplane, engine, and pilot. Given that the airplane was having difficulty climbing, as communicated by the pilot to air traffic control during the departure, it is likely that during the takeoff, the debris in the fuel manifold prevented the engine from obtaining full power.

The weight and balance record dated August 24, 1999, noted the airplane's empty weight to be 2,154 lbs. According to the Pilot Operating Handbook (POH) the maximum takeoff and landing weight for this aircraft was 3,600 lbs. With full fuel (94 gallons useable), an estimated cargo weight of 216 lbs, and reported pilot and passengers weights of 690 lbs, the total weight computed was 3,624 lbs. According to fueling records the airplane was topped off with 20 gallons of fuel prior to departure. The estimated cargo weight was based on the fire damaged items that were collected during the airplane recovery. The airplane's calculated takeoff distance assuming that it was loaded to its maximum gross weight, the flaps were set to 25 degrees, and given the weather conditions reported about the time of the accident, was about 1,050 feet. The distance required to clear a 50-foot barrier was about 2,000 feet. An autopsy was performed on the pilot by the DeKalb County Medical Examiner, Decatur Georgia. The Federal Aviation Administration's Civil Aerospace Medical Institute performed forensic toxicology on specimens from the pilot with negative results for drugs and alcohol. The wreckage was located in the eastbound lane of interstate 285, approximately 2 miles from PDK. The airplane came to rest in the left service lane against a 5 foot barrier wall on a heading of 021 degrees magnetic. There was a postcrash fire that consumed the majority of the airplane. There were ground scars across four traffic lanes up to the concrete highway divider. The cockpit and fuselage were fragmented and destroyed by postcrash fire. Flight control cables were attached to fragments of the flight controls. The right and left wings were fragmented and was destroyed by postcrash fire. The flight control surfaces were molten metal on both wings. The aileron bellcranks on the left and right wings were located within the fragments of the wings and connected to the flight control cables and turnbuckles. Flight control cable separations exhibited signs of overstress failures. The empennage was fragmented and fire damaged. The flight control cables to the rudder control sector and stabilator bell crank remained attached to the fragmented fuselage and were traced to the forward section of the cockpit. The left and right main landing gear were found in the extended position and the flap handle was impact damaged and observed in the 10-degree flap extension position. The throttle was found forward in the "full power" position, the propeller lever was forward at the "full increase" position, and the mixture lever was full forward at the "full rich" position. The fuel boost pump switch and selector was destroyed. Engine control linkage continuity was established from the cockpit controls to their respective engine connections. An examination of the fuel system revealed that the all of the fuel lines before the firewall were destroyed. The fuel lines from the firewall to the fuel manifold were partially fire damaged. The fuel manifold and injector lines did not show signs of fire damage. The fuel manifold was removed during the examination of the engine and placed on a test bench and did not flow when tested up to 7 psi (normal test pressure is 4.5 psi). The unit was removed from the test bench and the bottom cover was removed. Following removal of the bottom cover, the gasket did not exhibit heat damage. The bottom portion of the movable portion of the body assembly was measured and found to be positioned 0.032 inch below the spool of the body assembly (normal closed position). The bottom of the movable portion of the body assembly was pushed by hand and some resistance was noted at first, but it then moved. The bottom cover was reinstalled and the four screws were torqued to the proper setting. The fuel manifold was placed on the test bench and debris was noted coming from the ports during initial flow. The unit was flowed at 4.5 psi (normal) and it was found to flow equally from all ports at 132 pounds-per-hour (pph); the minimum specification was 135 pph. The fuel manifold was removed from the test bench and the top cover, which was safety wired, was removed. Test bench fluid was noted on the top side of the diaphragm (air side) and some slivers of material were also noted. The movable portion of the body assembly was removed and contamination/debris was noted. Re-insertion of the movable portion of the body assembly into the body revealed slight binding. The debris recovered from the fuel manifold was forwarded to the NTSB Materials Laboratory and examined using Fourier-transform infrared spectroscopy. The spectrum for the debris contained peaks that corresponded to signatures indicative that the material contained a carboxylic acid. A spectral library search was done on the debris spectrum. There were no strong matches found in the search; however, the debris spectrum had many similarities to several dicarboxylic acids, such as terephthalic acid and isophthalic acid. Carboxylic acids are pervasive in nature and are often found as precursors in polymer production, in adhesives and coatings, and are often naturally present in fuel as well as used as fuel additives (corrosion inhibitors and lubricity improving additives). During examination of the fuel servo, it was noted that it was fire damaged. Due to the heat damage of the diaphragms, the unit could not be flow tested. Examination of the propeller revealed that one blade was fractured off the hub. The spinner dome separated from the spinner bulkhead. All three blades exhibited rotational scoring and curling of the blade tips. There were impression marks on the preload plates indicating that the propeller was in the low blade angle position prior to impact. The propeller showed signs of power ON prior to impact. There were no discrepancies noted that would preclude normal operation. All damage was consistent with impact damage. The propeller governor was mounted in a governor test stand and run through the standard factory acceptance test procedure for new or overhauled governors. The governor functioned normally and met all factory specifications, except for the maximum rpm. The governor maximum rpm setting was 2,660 rpm verses a factory specification of 2,555 +/- 10. Although the high rpm setting was higher than factory specifications, it did not affect the governor performance. A higher than specified rpm setting indicated an adjustment was made to the governor high rpm stop while installed on the airplane. The governor was then disassembled for visual examination of the governor components. There were no unserviceable conditions noted during the visual examination. Examination of the engine revealed it was discolored consistent with exposure to the postimpact fire. The propeller and crankshaft flange were separated from the engine. The crankshaft flange was impact damaged. The left side of the exhaust system was crushed. The engine accessories were fire damaged. Both crankcase halves were fractured in the area of the No. 1 and No. 2 cylinders. The No. 2 cylinder head on the left side was impact damaged. The engine mount was bent and the engine was displaced toward the firewall. Three of the four engine mounts were impact fractured. The engine could not be rotated by turning the crankshaft flange due to impact damage and was further disassembled to examine the engine internal components. The cylinders were removed and no damage noted to the cylinders, pistons or valves other than fire and impact damage. The oil sump was removed and contained an unmeasured quantity of oil. The accessory case was removed and no damage to the rear gears was noted. The oil pump was disassembled and no damage to the pump bore or gears was noted. The crankcase halves were disassembled and the crankshaft and rod assembly was lifted out. The rods were free to rotate on the crankshaft rod journals and were not disassembled. The crankshaft