Incident Details
On 15 March 2002 at 0700Z, a Cessna 172M, registration ZS-JMK, was involved in a ground incident at the fuel bay of Wonderboom Aerodrome during training operations. The aircraft had one student pilot on board; no other persons were aboard. Weather conditions were CAVOK. There were no injuries or fatalities.
Sequence of Events
The student pilot was preparing for a dual navigation exercise and taxied the aircraft to the fuel pumps for refuelling. After refuelling, he made four attempts to start the engine without success. He then made three further attempts while 'pumping' the throttle lever, but the engine still failed to start. After waiting approximately five minutes, he attempted again, again to no avail. He then used two pumps of the primer pump and once more attempted to start the engine. At that point, he noticed flames appearing at the left-hand side of the engine cowling. He vacated the aircraft as quickly as possible. The fuel pump attendants had difficulty operating their fire extinguisher, and the fire was extinguished by another person standing nearby.
Damage
The engine sustained damage to its electrical wiring, and the engine cowling was slightly burned.
Probable Cause
It is believed that the pilot over-primed the engine prior to start-up, which resulted in excess fuel collecting in the inlet manifold, which ignited and caused a minor engine cowling fire.