History of Flight
On May 29, 2023, at approximately 1130 mountain daylight time, a Cessna 172B airplane, registration N8098X, sustained substantial damage during a forced landing near Divide, Colorado. The pilot and passenger received minor injuries. The flight was conducted under Title 14 Code of Federal Regulations Part 91 as a personal flight.
The pilot reported that the local flight to Antero Reservoir proceeded without incident after departing from Meadow Lake Airport (FLY) in Colorado Springs, Colorado. While returning to FLY at an altitude of 10,000 feet msl, the pilot heard a loud, sudden noise and the engine immediately lost partial power. Prior to the loss, engine rpm had remained steady at about 2,400 rpm with normal oil pressure. The pilot attempted to restore power by adjusting the throttle, testing both magnetos, and applying carburetor heat, but these actions did not produce a substantial power increase. He then elected to perform a forced landing.
After touching down in a large grassy area, the airplane encountered rough terrain, causing the nose landing gear to collapse. The airplane nosed over and came to rest inverted, resulting in substantial damage to both wings and the fuselage.
Examination Findings
The wreckage remained inverted in the field for about three weeks before recovery. An examination took place at the owner's residence on August 3, 2023. Both wings had been removed during recovery; no fuel was present in either wing fuel tank. The tank caps were found locked with intact gaskets. The pilot reported that 25 gallons of fuel were onboard at departure.
The fuselage fuel system showed no blockages. Less than a pint of fuel was recovered from the fuselage fuel lines at the engine firewall. The gascolator contained fuel. The recovered fuel was blue with a smell consistent with 100LL Avgas and tested negative for water contamination. The fuel screen was clear of debris. The fuel selector valve was in the BOTH position and rotated correctly when moved manually.
The engine remained attached to its mount. The throttle and carburetor heat cables were attached to the carburetor and airbox, respectively. The mixture cable had separated from the carburetor with damage consistent with impact. The carburetor heat door operated normally when tested by hand. The ignition system, tested by manually rotating the propeller with the ignition key on BOTH, produced spark on all spark plug leads.
No blockages were found in the carburetor venturi, throttle plate, fuel inlet ports, or fuel nozzle. The throttle plate moved freely through its full range. The carburetor bowl and floats were removed; no fuel or foreign material was present in the bowl.
The air intake and exhaust system were inspected with a borescope; no blockages or issues were found. The Brackett engine filter was intact and clean.
The Cessna 172B Owner’s Manual and Airworthiness Directive 72-07-02 state that the fuel selector should be switched to single tank operation at cruise altitudes above 5,000 feet to avoid fuel vapor formation in the fuel lines. The manual further advises that if power irregularities due to fuel vapor occur during operation on BOTH tanks, the pilot should switch to a single tank for 60 seconds, then switch to the opposite tank to restore power. The pilot stated that during troubleshooting, he verified the fuel selector remained in the BOTH position.