Salmon, ID, USA
N7748U
CESSNA 172
The flight instructor stated that during an instructional flight, he configured the airplane for a simulated engine failure by applying carburetor heat and decreasing the engine power. The student pilot followed emergency procedures, used the checklist, and prepared to land. When the carburetor heat control was pushed back in and the throttle was advanced, the engine suddenly lost power. The flight instructor tried restarting the engine to no avail and initiated a forced landing, during which the airplane struck a fence. Postaccident examination of the airplane revealed that the original inline fuel strainer was replaced with an aftermarket inline fuel strainer with a manual sump valve on the strainer bowl. The inline fuel strainer drain knob from the original fuel strainer was removed from the instrument panel. The fuel strainer was drained and found to be filled about 3/4 with water. The student pilot stated that the only sumps that were drained during the preflight inspection were the wing tank sumps. He further stated that he did not know about the fuel strainer having a sump and that the flight instructor never told him about it. The flight instructor stated that he performed a preflight inspection after the student pilot had drained the wing tanks and fuel strainer sumps. He further stated that he thought the student pilot found some water in the left wing tank but did not drain the fuel strainer. It is likely that the engine lost power due to water in the inline fuel strainer, which led to the forced landing.
On July 2, 2016, about 1100 mountain daylight time, a Cessna 172E airplane, N7748U, was substantially damaged during a forced landing, 10 miles east of Salmon, Idaho. The student pilot and the flight instructor were not injured. The airplane was registered to Spirit Air, Inc., and the flight instructor was operating it as a Title 14 Code of Federal Regulations (CFR) Part 91 instructional flight. Visual meteorological conditions prevailed, and no flight plan was filed for the local flight which originated from Lemhi County Airport (SMN), Salmon, Idaho at an unknown time. The flight instructor stated that during the flight they had performed various private pilot training maneuvers. He further stated that he set the airplane up for a simulated engine failure by applying carburetor heat and decreasing the engine power to 1,200 rpm. The student pilot followed emergency procedures, used the checklist, and prepared to land. After the carburetor heat control was pushed back in and the throttle advanced, there was a sudden loss of engine power. The flight instructor stated that there was no coughing or hesitation during the power loss. Despite the flight instructor's efforts, he was unsuccessful in restarting the engine and initiated the forced landing. During the forced landing, the airplane's right horizontal stabilizer struck a fence which resulted in substantial damage. Post accident examination of the recovered wreckage was conducted by a Federal Aviation Administration (FAA) inspector. The airplane's wings were removed to facilitate transportation of the wreckage. During the wreckage recovery, 10 gallons of fuel was collected from the left-wing fuel tank and 8 gallons of fuel was collected from the right-wing fuel tank. The inspector reported that the wing tanks were intact, and the fuel vents were clear of debris. The wing tank caps were examined and both cap rubber seals had cracking around their outer circumference. The right-wing tank filler neck was heavily corroded with deep pitting. The inline-fuel strainer had been installed on the airplane in accordance with Steve's Aircraft STC SA01026SE. This inline-fuel strainer replaced the original inline strainer positioned on the firewall. The new strainer was not equipped with the option of draining the bowl from the cockpit and has a manual sump valve on the bowl. The strainer was drained from the sump during the examination and revealed that the strainer bowl was three-quarters full of water. The strainer bowl was removed and had small amounts of debris. The cockpit strainer drain knob was removed from instrument panel, but was not placarded "inoperative." The engine's fuel lines were secure and in good condition. The carburetor was examined and showed normal operating signatures. The carburetor bowl was removed and contained a small amount of fuel and no contaminates. The cylinders were examined with a boroscope and showed normal operating conditions. The No. 1 cylinder exhaust valve head revealed a small chip missing, resulting in a low pressure during the cylinder compression test. The remaining cylinders had normal compression pressures. The crankshaft was rotated, and spark was produced at each ignition lead. The ignition switch, P-leads and magnetos revealed no anomalies. The FAA inspector conducted separate interviews with the student pilot and flight instructor. The student pilot stated that the only fuel drains that were sumped during the preflight inspection prior to the accident flight, were the main wing tanks. The student pilot further stated he did not know about the fuel strainer sump, and that the flight instructor never showed him. The flight instructor stated that he had performed a preflight inspection after the student pilot had drained the wing tanks and fuel strainer sumps. The flight instructor remembers that the student pilot found a small amount of water in the left-wing tank but didn't drain the fuel strainer. He concluded by stating that there was no other water was found during the preflight. A National Transportation Safety Board Pilot/Operator Aircraft Accident/Incident Report Form 6120.1 was not provided during the investigation.
A loss of engine power due to water in the fuel system. Contributing to the accident was an inadequate preflight inspection that failed to eliminate water from the fuel system.
Source: NTSB Aviation Accident Database
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