Flight History
On 29 October 2008, a Cessna 172 registered PK-SDQ, operated by Alfa Flying School, departed from Halim Perdanakusuma Airport in Jakarta at 00:40 UTC (07:40 local time) on a cross-country training flight to Penggung Airport in Cirebon. Onboard were one instructor, one observer, and one student pilot. The student pilot was controlling the aircraft. After departure, the aircraft climbed to 1,500 feet and proceeded to the BARUS point. After BARUS, it climbed to 2,500 feet and contacted Jakarta approach, requesting to climb to 5,500 feet.
Engine Failure and Forced Landing
At 01:10 UTC, while passing 5,000 feet over the PW NDB (Purwakarta area), the engine quit. The student pilot attempted to restart the engine but failed. The instructor took over control, transmitted a distress message (mayday), and selected transponder code 7700. At 01:15 UTC, the aircraft landed on the shoulder lane of the Jakarta–Cikampek highway, with a landing direction approximately 070, on the side of traffic toward Cikampek. No one was injured in the incident, and the aircraft sustained no damage.
Investigation Findings
The investigation determined that the engine failure was caused by the failure of the crankshaft idle gear, which stopped the rotation of the magneto and ignition system. This resulted in a complete loss of engine power. The aircraft was equipped with a Lycoming engine, and examinations of the engine and its components were conducted as part of the investigation.
Engine Examination
Post-incident examination of the engine revealed that the accessories gear case and internal components were disassembled for inspection. The crankshaft gear showed signs of disintegration, and the crankshaft idle gear was found to have failed. Metallurgical analysis was performed to understand the failure mechanism, but the source does not provide further details.