Accident Overview
On April 18, 2023, at approximately 10:02 JST, a Textron Aviation 172S aircraft, registration JA395A, operated by the Japan Coast Guard, performed a forced landing on farmland in Usa City, Oita Prefecture. The aircraft was destroyed but did not catch fire. Both occupants, a trainee and an instructor, sustained minor injuries.
Flight History
The flight departed Kitakyushu Airport at 09:19 JST for a training mission aimed at obtaining a commercial pilot certificate. The trainee occupied the left seat and the instructor the right. Due to a fuel leak the previous day, maintenance had replaced relevant components; this was the first flight after the repair and engine run-up including maximum output was completed.
At about 09:53, while climbing from 3,250 ft at 100% engine output, a strange banging sound was heard from the front, and the engine output indication dropped from 100% to 60% without any warning. The instructor took control, reduced the power lever to 60%, and decided to return to Kitakyushu Airport. A nearby aircraft (JA391A) observed black smoke from the exhaust.
Despite maintaining 90 kt with 60% output, altitude decreased. At 09:58, moving the power lever to 100% did not increase output beyond 65%, and reducing it caused a corresponding decrease. The instructor judged that reaching Kitakyushu was impossible and selected a southbound course due to southerly winds. At 09:59, the instructor declared a forced landing.
During descent, the instructor activated the ELT and instructed the trainee to set transponder code 7700. The brace position was assumed, doors unlocked, and a farmland site without overhead wires was selected. At touchdown, the aircraft landed in soft soil (wheat up to 100 cm high) and came to rest inverted after taxiing about 25 m. Both exited the aircraft without fire.
Aircraft and Damage
The aircraft (Textron Aviation 172S, serial 172S11735) had a total flight time of 1,390 hours. The engine (Technify Motors TAE 125-02-114) had 1,382 hours. Post-accident inspection revealed the intake hose connecting the turbocharger to the engine intake manifold was disconnected at the intercooler outlet; one of two clamps was missing and corroded. Propeller blades were broken, wings and tail damaged, fuselage deformed and cracked. Batteries had leaked. No significant exterior engine damage was noted.
Occupants
Both pilot and instructor held valid certificates and medicals. The trainee had 211 total flight hours, the instructor 5,960 hours. No injuries beyond minor were reported.
Weather
Cloudy conditions with south wind at 10 kt and good visibility, as reported by the instructor.