What happened
On 16 February 2004, a Reims Cessna F150M, registration G-BDSL, was conducting a training flight at Netherthorpe Airfield in Nottinghamshire. The flight involved an instructor and a student pilot. During the takeoff roll on grass Runway 24, the student performed a 10-degree flap takeoff. Shortly after the flaps were retracted at approximately 300 feet, the engine experienced a loss of power characterized by fluctuating RPM between 1,000 and 2,000.
Upon the loss of power, the instructor assumed control of the aircraft and identified a suitable area for a forced landing. Due to trees obstructing the path directly ahead, the instructor attempted a left turn to return to the airfield. However, the reduced engine power prevented a standard circuit and approach to Runway 2able. The aircraft instead entered a close-in left base leg for Runway 36. The instructor configured the aircraft with full flaps and crossed the threshold at 60 kt. After bouncing on the uneven, wet, and muddy grass surface, the aircraft settled, but full braking proved ineffective. The aircraft overran the runway and struck a runway end stop sign, causing the nose landing gear to collapse. The aircraft pitched forward and came to rest in an inverted position. There were no injuries to the two crew members.
The investigation
Investigators examined the engine and the landing conditions at the airfield. The investigation focused on the cause of the power fluctuations and the factors that contributed to the extended landing roll on the grass surface. Engineering analysis of the engine was also conducted to identify any mechanical failures within the cylinder components.
Findings
- The primary cause of the power loss was significant carbon deposits around the exhaust valve guide in one of the cylinders, which likely caused the exhaust valve to stick intermittently.
- The extended landing distance was caused by a combination of the downward slope of the surface, a tailwind, a bounce during the initial touchdown, and ineffective braking due to the wet and muddy grass.