Partial power loss during Cessna 210 takeoff linked to incorrect mixture setting

Casualties unknown • Groote Eylandt Airport, Northern Territory

An investigation into a Cessna 210 takeoff incident revealed that an incorrect engine mixture setting caused significant power loss and engine instability.

What happened

Shortly after lifting off at an altitude of approximately 100 ft, the Cessna 210 experienced engine surging and fluctuations in fuel flow. Data from the engine management system showed fuel flow averaging 66 L/h, which was significantly lower than the levels recorded during previous take-offs that same day. Additionally, exhaust gas temperatures were approximately 48 °C higher than normal. The pilot, facing a situation where the remaining runway was insufficient for a landing, attempted to maintain a safe airspeed and climb. However, the aircraft was operating 10 kg above its maximum takeoff weight, which likely hindered its climbing performance.

The investigation

The ATSB examined the engine performance and the aircraft's mechanical state. While the engine-driven fuel pump had exceeded its overhaul life, testing showed it was functioning normally. No mechanical failures, fuel contamination, or fuel vaporization issues were identified in the engine or fuel system. The investigation focused on the air-fuel ratio, noting that the reduced fuel flow and elevated exhaust temperatures were consistent with a lean mixture. The investigation found that while the operator requires a 'ground lean' setting for ground operations, procedures require the mixture to be set to 'full rich' for takeoff. The data suggests the mixture was left in the 'ground lean' position.

Findings

  • The primary cause of the power loss was the engine mixture control being left in the 'ground lean' position instead of being set to 'full rich'.
  • The pilot's perception of time pressure and relative inexperience with this specific aircraft model may have led to the oversight of the mixture setting.
  • The pilot did not attempt to troubleshoot the engine behavior by checking the mixture control once the power loss occurred.
  • The pilot's takeoff safety briefing lacked specific procedures for managing a partial power loss.
  • The aircraft was operating 10 kg above its maximum allowable takeoff weight because weight and balance calculations were not completed due to time pressure.
  • The aircraft was equipped with an engine-driven fuel pump that had exceeded its service life.

Probable cause

The partial power loss was caused by the pilot failing to set the engine mixture control to the full rich position prior to takeoff, resulting in an overly lean air-fuel ratio. This was compounded by time pressure and the pilot's failure to troubleshoot the engine issue during the flight.

Frequently asked questions

What happened in the 2023-06-16 Cessna Aircraft Company 210L accident near Groote Eylandt Airport, Northern Territory?

An investigation into a Cessna 210 takeoff incident revealed that an incorrect engine mixture setting caused significant power loss and engine instability.

What aircraft was involved and where did it happen?

The accident on 2023-06-16 involved a Cessna Aircraft Company 210L, registration VH-FTM, operated by Katherine Aviation Pty Ltd, at Groote Eylandt Airport, Northern Territory.

What was the probable cause of the accident?

The partial power loss was caused by the pilot failing to set the engine mixture control to the full rich position prior to takeoff, resulting in an overly lean air-fuel ratio. This was compounded by time pressure and the pilot's failure to troubleshoot the engine issue during the flight.

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