Engine failure and inverted landing of Cessna U206G at Clonbullogue Airfield

Casualties unknown • IE

A Cessna U206G experienced a significant power loss during a parachute drop operation, resulting in an emergency landing in a field near Clonbullogue Airfield.

What happened

On 15 March 2009, a Cessna U206G Stationair operated by the Irish Parachute Club Limited was conducting a parachute drop mission near Clonbullogue Airfield, Co Offaly. During the aircraft's sixth flight with the operator, the pilot experienced a major loss of engine power while climbing through 9,000 feet. Following the power loss, the pilot ordered the parachutists to exit the aircraft.

In an attempt to return to the airfield, the pilot attempted an emergency descent, but the aircraft was unable to reach the runway. The aircraft subsequently touched down in a ploughed field located short of the landing strip. The impact caused the nose undercarriage to partially collapse, leading the aircraft to pitch forward and come to rest in an inverted position. The aircraft sustained substantial damage, though the pilot escaped without injury.

The investigation

The investigation focused on the cause of the engine failure and the state of the aircraft's fuel system. Post-accident inspections revealed that the fuel tanks and the fuel system itself had not sustained any damage during the impact, and no fuel spills were detected. However, the left-hand tank was found to be empty, while the right-hand tank contained only 2 litres of fuel.

Investigators examined a modification to the fuel system performed under a Supplementary Type Certificate (STC). This modification added extra bladder tanks outboard of the standard Cessna tanks, which included sealing the original filler points and installing new filler points on the top of the bladder tanks. The investigation noted that the aircraft's fuel quantity indication relied solely on the original Cessna float gauges located in the main tanks.

Findings

  • The investigation identified a slow fuel transfer rate from the supplemental bladder tanks into the primary tanks.
  • Because of this slow transfer, measuring fuel levels immediately after refueling led to an inaccurate reading; the initial dipstick measurement over-read the actual quantity by approximately 100%.
  • The fuel starvation caused by the inaccurate fuel management is considered the probable cause of the engine failure.

Probable cause

The engine failure was likely caused by fuel starvation, resulting from an erroneous fuel quantity reading that over-estimated the available fuel due to the slow transfer rate from modified bladder tanks to the main tanks.

Frequently asked questions

What happened in the null aircraft accident near IE?

A Cessna U206G experienced a significant power loss during a parachute drop operation, resulting in an emergency landing in a field near Clonbullogue Airfield.

What aircraft was involved and where did it happen?

The accident on null involved a aircraft, registration EI-HOG, at IE.

What was the probable cause of the accident?

The engine failure was likely caused by fuel starvation, resulting from an erroneous fuel quantity reading that over-estimated the available fuel due to the slow transfer rate from modified bladder tanks to the main tanks.

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