What happened
On October 6, 2018, a Cessna U206G was conducting skydiving operations at Zamość Aerodrome (EPZA). The aircraft was performing its ninth jump of the day, carrying five skydivers. After completing a pre-flight inspection and verifying fuel and oil levels, the pilot commenced the takeoff roll under Visual Meteorological Conditions (VMC).
During the takeoff roll, the aircraft reached an altitude of approximately 5 meters when the engine lost power. The pilot immediately declared an engine failure, aborted the takeoff, and successfully brought the aircraft to a stop on the runway. Following the stop, the pilot ordered an evacuation of the passengers due to smoke emanating from the engine compartment and the suspicion of an engine fire. Upon inspection, no active fire was found. The investigation later revealed that a connecting rod from the third cylinder had pierced the engine crankcase.
The investigation
Technical examinations of the engine were conducted by LOMA AIR in Belgium. The investigation established that the failure originated from the breakage of a bolt securing a connecting rod. The loss of this bolt led to significant mechanical damage to various internal engine components.
Investigators also examined the JPI EDM 830W engine monitor. It was discovered that the device's recording interval had changed from 6 seconds to 8 minutes and 30 seconds starting in July 2018. This undetected configuration error significantly reduced the density of the available data, preventing the detection of the specific engine parameters leading up to the failure.
Findings
- The primary cause of the engine failure was an over-speed event (engine overspeed) occurring during a previous flight.
- The failure of the connecting rod bolt caused the subsequent destruction of the engine internals.
- An undetected change in the engine monitor's recording frequency prevented the capture of high-resolution data necessary to identify the exact moment of the overspeed.