Synopsis
A Cessna F150L, registration G-AYKL, sustained severe damage to its propeller, fuselage, and wings after striking the ground during a departure from Netherthorpe Airfield on 16 August 2006. The private flight was carrying one pilot and one passenger; both received minor injuries.
History of Flight
The pilot and passenger arrived at Netherthorpe at approximately 1240 hrs. After performing a daily inspection and a satisfactory fuel sample check, the pilot refueled the aircraft with 29.5 litres, bringing the tanks to just under half full. Engine start and power checks were normal; the pilot briefed the passenger on the actions performed, including magneto and carburettor heat checks.
Taxiing to Runway 24, the pilot executed pre-takeoff checks, including an additional carburettor icing check (none evident). Flaps were set to 10°. The wind was light from 270°, visibility about 8 km, with broken cloud at 3,000 ft. The pilot described the ambient temperature as warm but not hot.
Upon applying full throttle, initial acceleration was normal. At the intersection of the two runways, the indicated airspeed was 45 mph, which was normal. Shortly after, the rate of acceleration decreased. The pilot considered aborting the takeoff but believed insufficient runway remained; he raised the nose and lifted off.
The aircraft climbed slowly to approximately 50 ft. The pilot then lowered the nose to increase airspeed, but about 400 metres from the upwind end of the runway, the right wing dropped and the aircraft struck the ground in a grass field. Both occupants released their harnesses and exited through normal doors. The airfield Rescue and Fire Fighting Service attended promptly.
Weight and CG
The calculated takeoff weight was 1,591 lbs, with the centre of gravity at +34.9 inches from the manufacturer's datum. This was near the maximum takeoff weight of 1,600 lbs, and the CG was close to the mid-point of its permitted range.
Performance
Runway 24 is 553 metres long, 36 metres wide, with a grass surface that was dry, hard, and recently mown. It has a 1.9% uphill slope, and the airfield elevation is 254 ft amsl. The Owner's Manual gives takeoff distance data for level, hard, dry grass. For 15°C and zero headwind with 10° flaps, the takeoff run required (TORR) is 220 metres and takeoff distance to 50 ft (TODR) is 460 metres. At 34°C, the TORR becomes 242 metres and TODR 506 metres. The CAA Safety Sense Leaflet suggests a 10% increment for a 2% uphill slope, increasing TORR to between 242 and 266 metres.
The Owner's Manual states that normal and obstacle clearance takeoffs should be performed with flaps up; 10° flaps can shorten ground run but the advantage is lost in the climb to 50 ft. The pilot had previously operated from Runway 24 in similar conditions with 10° flaps and near maximum weight without issues.
Analysis
The pilot conducted pre-takeoff checks normally, including carburettor heat which was selected off before departure. Runway length was adequate per manufacturer's performance requirements, even with the Public Transport safety factor of 1.33. No explanation for the loss of engine power was identified; ambient temperature was described as warm rather than hot. The wing drop and loss of control were attributed to the pilot's attempt to maintain or increase height, resulting in a loss of airspeed and subsequent stall.