ERA25LA012

During a familiarization and check-out flight, and after completing several maneuvers about 25 miles from the departure airport, the pilots elected to return to the departure airport. After turning on an approximate 8-mile final approach, the pilot had the engine set to a low power setting, the carburetor heat on, and switched the fuel tanks. After the airplane had descended to about 1,000 ft mean sea level (msl), the pilot reported that the engine’s throttle was unresponsive. The instructor took control of the airplane and attempted to perform a forced landing in a grassy area beside a road. During the approach for landing, the airplane impacted a light pole and an automobile. Postaccident examination of the wreckage revealed that the both wings, the fuselage, and empennage had sustained substantial damage as a result of the accident. An initial examination of the wreckage found that the fuel selector valve was in between the two “OFF” detents; however, the airplane had been recovered before the wreckage could be examined and it could not be determined whether the as-found position was indicative of its position at the time of the accident. Testing of the valve in this position revealed that flow from the valve was completely obstructed. Further testing revealed that the valve’s detents were positive, and that it functioned normally when the left and right fuel tanks were selected. Further examination of the airframe’s fuel system revealed that the main vent system for the left fuel tank was obstructed; however, the vented cap for the left fuel tank was unobstructed, which would have allowed proper venting of the left fuel system. The carburetor underwent additional testing on a production test bench and was disassembled and examined. The carburetor performed normally with a slightly leaner fuel flow when tested at two of the test points. Further examination revealed that the throttle valve shaft and bushings displayed wear, allowing side motion of the throttle shaft, which could have allowed a small amount of bypass air to enter the throttle body, and lean the fuel/air mixture. It is likely that the slightly lean postaccident tests were a result of the worn throttle valve shaft and bushing; however, this small amount of leaning would not have prevented normal operation of the engine. The weather conditions at the time of the accident were conducive to serious carburetor icing at low power settings. According to the pilot, the carburetor heat was used during the final approach. The position of the carburetor heat control and valve could not be confirmed during the postaccident examinations due to the impact damage to both the control and the carburetor airbox; therefore, the functionality of the carburetor heat could not be confirmed. Overall, the wreckage examination was unable to identify evidence of any preimpact mechanical malfunctions or failures of the airframe or engine would have precluded normal operation. The impact-related damage tothe airplane and engine otherwise prevented a test run that could have checked the various systems as a whole.

On October 11, 2024, at 1820 eastern daylight time, a Piper PA-28, N5006W, was substantially damaged when it was involved in an accident near Louisville, Kentucky. The private pilot sustained minor injuries, the flight instructor sustained serious injuries, and two occupants of an automobile on the ground received minor injuries. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 instructional flight. According to the private pilot, the purpose of the flight was a familiarization and check out in the airplane, as she reported most of her previous experience was in Cessna 172 airplanes. The pilot reported that the preflight inspection was normal without any anomalies found, and the flight instructor reported that the airplane’s fuel load was confirmed to be about 36 gallons total. The engine start, engine runup, takeoff, and departure from Bowman Field Airport (LOU), Louisville, Kentucky, were all normal. ADS-B data showed that after performing several maneuvers about 25 miles north of the airport, the airplane began to track back towards LOU. The data further showed that, about 8 miles northeast of the airport, the airplane made a right turn toward the airport. The pilot reported that while on final approach to land, the flight instructor directed the pilot to switch fuel tanks. She then turned on the fuel pump, confirmed that the fuel pressure was in the green, and pulled the fuel selector knob toward her. The pilot also stated that the carburetor heat was in the “ON” position during the final approach. A couple of minutes later, at an altitude of about 1,000 ft mean sea level, she noticed the engine was losing power. The pilot moved the throttle forward, and noted that the engine rpm rose slightly before dropping again. The pilot then reported to the instructor that “I have no throttle.” The flight instructor then took control of the airplane, declared an emergency to air traffic control, and performed a forced landing on a grass median, adjacent to a nearby road. During the forced landing, the airplane impacted a light pole and an automobile. At 1842, the weather conditions reported at LOU, located about 1 nautical mile southwest of the accident site, included a temperature of 22°C and a dew point 9°C. The calculated relative humidity at this temperature and dewpoint was 43 percent. Review of the icing probability chart contained within Federal Aviation Administration Special Airworthiness Information Bulletin CE-09-35 revealed the atmospheric conditions at the time of the accident were "conducive to serious icing at glide [idle] power." A review of the engine logbooks revealed that the engine had not been overhauled since it was installed on the airplane on October 18, 1963. The logbook entry detailing the engine installation also documented the engine's disassembly and repair after a propeller strike, and noted that the engine had a total time of 147 hours since new. A copy of this entry was in a folder section forthe engine overhaul, but the logbook entry did not state it was an overhaul. According to Lycoming Service Instruction 1009BE, an O-320-D2A should be overhauled every 2,000 hours or every 12 years, whichever occurs first. According to the flight log, about 7 days prior to the accident, the engine had accrued a total of 2,453.7 hours. Postaccident examination of the airplane revealed that the airframe had sustained substantial damage to both wings, fuselage, and empennage. Flight control continuity was established for the rudder, stabilator trim, both ailerons, and the flaps through breaks that were consistent with recovery cuts. Flight control continuity was established for the stabilator through a break consistent with a recovery cut and another consistent with tension overload. The flap handle was found in the 2nd notch position. The throttle and mixture controls were found near the full forward positions. The carburetor heat control was impact-damaged, and its position could not be positively determined. During the initial examination of the airplane, the fuel selector valve was found between the two “OFF” detents; however, the airplane had been recovered to a local hangar prior to the examination. During testing, no air was observed when blowing low-pressure air through the valve when it was in between the “OFF” detents. The fuel selector valve was tested in the “LEFT” and “RIGHT” positions utilizing low-pressure air, and the selector valve operated normally. Tactile detents were present in each position of the selector valve handle. The fuel line going from the airplane’s firewall to the fuel strainer was noted to be kinked and displayed dry rot; however, it was not obstructed. The fuel strainer bowl had partially separated, which was consistent with the observed impact damage. The strainer screen was removed, was found to be unobstructed, and the strainer bowl was clean. Fuel line continuity was established from the fuel selector valve to the left and right fuel tanks; they were found to be unobstructed, and all separations were consistent with impact damage and recovery cuts. Both fuel tank inlet screens were observed and were found to be unobstructed. The right fuel tank vent line was found to be unobstructed from the fuel tank to the outboard vent. The left fuel tank vent line was found to be obstructed and was cleared using low-pressure air; the obstruction could not be located after clearing the vent line. The left fuel tank cap was a vented cap, and the vent galleys were clear of obstructions. The left fuel tank cap gasket was found to be dry-rotted; however, it remained pliable. The right fuel tank vented cap gasket and vent gasket were found to be pliable; however, the gasket was dry-rotted. The airframe electrically-driven fuel pump was removed and tested by connecting to a 12V battery; the fuel pump was audibly operable. The engine remained attached to the airframe through the engine mounts, hoses, wires, and cables. The enginewas removed from the airframe to facilitate examination. Continuity was established between the crankshaft, camshaft, connecting rods, and associated components by rotating the propeller by hand 720°. All four cylinders displayed good thumb compression and suction. The overhead components (valves, springs, and rocker arms) displayed normal operating and lubrication signatures and operated normally during crankshaft rotation. The cylinders were inspected using a lighted borescope; the piston faces, cylinder walls, and valve heads displayed normal operating and combustion signatures. The oil filter was removed, and the housing was cut open. The filter pleats were inspected, and no anomalies were observed. During crankshaft rotation, it was observed that the oil pump was capable of pumping residual oil. The fuel pump remained attached to the engine, and both fuel lines were secure. The fuel pump was removed, and the fuel pump plunger was found to operate normally. The fuel pump was manually actuated and was found to be capable of pumping air. The fuel pump was disassembled, and the internal components displayed normal operating signatures. The fuel line going to the carburetor remained secure, and there were no signs of fuel leaks. Engine control continuity was established by moving the cockpit controls and observing throttle and mixture control movement at the carburetor. The carburetor mixture and throttle control arms were capable of normal movement, and the throttle valve operated normally. The fuel inlet screen was removed and was found to be clear of obstructions. The carburetor was retained for further testing. Both magnetos remained attached to their installation points and were undamaged. The magnetos were removed, and both were capable of creating a spark on all four of their respective posts. The ignition harness displayed impact damage concentrated near the magnetos. The ignition harness caps remained secured to each magneto, and each ignition lead remained securely attached to each spark plug; no signs of chafing or arcing were observed. The spark plugs were removed and displayed normal wear and operating signatures. The exhaust system remained attached to the engine and displayed impact damage signatures. The exhaust was removed, and there were no signs of exhaust leaks or obstructions observed. The induction system displayed impact damage to the airframe airbox. The carburetor heat valve was crushed and its position at the time of the accident could not be determined. The inlet air filter was impact-damaged and contained debris consistent with accumulation during the accident. The induction risers were undamaged, and no intake leaks or obstructions were observed. The carburetor was placed on a test bench, and a static pressure test was performed. The carburetor static pressure test indicated the bowl, floats, and float valve were operating normally. During the carburetor static test, the accelerator pump was tested; the acceleratorpump operated normally. The carburetor was then placed on a carburetor flow test bench. The carburetor performed normally with a slightly leaner fuel flow when tested at the 700 pounds per hour (PPH) and the 900 PPH air flow test point. At 700 Air PPH the fuel flow was 3.86 PPH lower than specifications. At the 900 Air PPH test, the fuel flow was 3.56 PPH lower than specifications. The carburetor was disassembled, and the internal components were examined. The disassembly revealed that the carburetor bowl and fuel inlet screen were clear of any contamination, and there was no corrosion observed within the bowl. The accelerator pump displayed normal operating and wear signatures. The accelerator pump check valve was installed correctly. The float height setting was checked and was found to be within specifications. The floats and the float valve were removed, and the float valve and seat displayed normal operating and seating signatures. The float, float valve retaining pin, and bracket displayed normal wear signatures. The mixture control assembly and mixture control sleeve displayed normal operating and wear signatures. The main fuel nozzle remained secure, and there were no obstructions or debris within the main fuel nozzle or the mixture control sleeve. The throttle valve operated normally during actuation; however, the throttle valve shaft and bushings displayed significant wear, allowing side motion of the throttle shaft. A dial indicator was placed against the shaft, and the linear movement averaged to be 0.019 inches. According to the AvStar technician, this could allow a small amount of bypass air to enter the throttle body, which could slightly lean the fuel/air mixture. However, the amount of wear would not have precluded normal operation of the throttle valve.