What happened
On May 7, 2018, a Cessna P210N, registration TG-TOT, was cruising at 21,000 feet when the pilot attempted to switch the fuel selector from the left tank to the right tank. During this procedure, the pilot did not follow the specific fuel transfer protocols outlined in the flight manual, resulting in fuel starvation due to air/gas entrapment in the fuel lines.
This caused the engine to stop. In an attempt to restart the engine in flight, the engine entered a windmilling state, which led to an extreme overspeed condition. Data from the JPI EzTrends system indicated the engine exceeded 3,490 RPM for more than 10 seconds. The aircraft subsequently lost control and descended into an irregular field in Aldea Santa Ana, Totonicapán. The pilot and passenger sustained minor injuries and were evacuated by local residents.
The investigation
The DGAC/UIA investigation focused on the mechanical state of the Continental IO-550-P engine and the sequence of pilot actions. Investigators examined the fuel delivery system, including the fuel pumps and return lines, finding them to be unobstructed and functioning normally.
Technical analysis of the engine's digital data confirmed the overspeed event. Upon disassembling the magnetos, investigators discovered severe damage to the distributor gears, specifically broken teeth. This mechanical failure prevented the engine from responding to restart attempts during the descent.
Findings
- The primary cause of the engine failure was fuel starvation caused by improper fuel selector manipulation, which introduced air into the lines.
- The engine experienced a significant overspeed event (exceeding 3,490 RPM) during the windmilling phase.
- The extreme RPM caused structural damage to the magneto distributor gears, rendering the ignition system unable to support an in-flight restart.
- The aircraft was in a proper state of airworthiness and maintenance prior to the event.
- Meteorological conditions at the time of the impact were favorable (CAVOK).