What happened
On 20 October 2001, a Rans S6-ESD Coyote II, registration G-MYSP, was performing a private flight near Lichfield, Staffordshire. Shortly after departing, the pilot initiated a right-hand climbing turn. At an altitude between 100 and 150 feet, the engine RPM dropped significantly from 6,200 to 5,000, accompanied by a decay in airspeed. In an attempt to recover speed, the pilot lowered the aircraft's nose, but the engine RPM subsequently failed completely.
As the aircraft progressed, the pilot encountered overhead wires crossing the flight path. To avoid these obstacles, the pilot had to reduce the descent angle, which further depleted the remaining airspeed and brought the aircraft near a stall condition. Having cleared the wires, the pilot attempted a dive to regain momentum; however, due to the minimal altitude remaining, the aircraft performed a very heavy landing. The impact caused substantial damage to the engine cowling, propeller, wings, and landing gear. There were no injuries to the pilot or the passenger.
The investigation
The AAIB investigation examined the engine and environmental conditions. A strip examination of the Rotax 503 engine, conducted alongside a PFA inspector, revealed no mechanical defects. The engine remained capable of running at idle after the propeller was removed and the exhaust pipe was cleared of soil.
Meteorological data from the area indicated a temperature of 15°C and a dewpoint of 13°C, with a surface humidity of 88%. Analysis of these conditions using established icing charts indicated that a float carburettor engine would be at high risk for serious icing. The investigation also noted that another microlight pilot operating nearby had reported experiencing carburettor icing on the same day.
Findings
- The primary cause of the power loss was likely carburettor icing.
- Although the engine was at a climb power setting, ice may have accumulated during ground running at low throttle or built up during the initial climb.
- The aircraft was not equipped with a carburettor heat system, nor did it have an external electrical heating system designed to prevent ice formation.
- The heavy landing was necessitated by the need to clear overhead wires after the engine power failed.