What happened
On 3 January 2002, a PIPER PA34-200T, registration ZS-JZR, was conducting a private flight from a farm aerodrome near Standerton toward Pietermaritzburg Aerodrome. The flight was being conducted under Instrument Meteorological Conditions (IMC).
Roughly 17 minutes before the aircraft was scheduled to reach the ORI beacon at Pietermaritzburg, the pilot noticed a significant drop in fuel flow to the left-hand engine, which fell from 12.6 to 8 gallons per hour. In an attempt to maintain engine operation, the pilot engaged the auxiliary electric fuel pump on its high setting. However, during the final approach phase, the left-hand engine failed completely. This forced the pilot to perform an emergency landing on school grounds located approximately one nautical mile north of the Pietermaritzburg Aerodrome threshold. While there were no fatalities, the impact caused substantial damage to the aircraft and resulted in one injury to a passenger.
The investigation
SACAA AIID investigators examined the mechanical history of the aircraft and the fuel system. The investigation established that the left-hand engine had exhibited various fuel flow irregularities during previous flights. Although two maintenance engineers had attempted to resolve these issues prior to the accident, their efforts failed to rectify the underlying problem. The aircraft's maintenance records showed it was being kept according to the approved schedule, with the most recent Mandatory Periodic Inspection completed in May 2001.
Findings
- The primary cause of the engine failure was a loose tube nut within the left-hand engine's fuel system.
- This improperly tightened nut allowed air to enter the fuel line, which compromised engine performance.
- The failure of the engine during the final approach was specifically attributed to an over-rich mixture condition, exacerbated by the use of the auxiliary fuel pump on the high setting.
- Previous maintenance attempts failed to identify the specific loose component causing the fuel flow fluctuations.