What happened
On the morning of 9 June 2002, a pilot initiated a VFR flight from Kimberley, intending to fly via Potchefstroom to George. During the initial climb following takeoff, the pilot observed that the oil pressure gauge was indicating zero pressure. Despite this, other engine parameters, including oil and cylinder head temperatures, appeared normal.
After notifying Johannesburg Information of the issue, the pilot diverted to Klerksdorp. Upon landing, a manual check of the dipstick showed the engine oil level was at 12 quarts. Following discussions with other pilots, who suggested the reading might be a faulty gauge, the pilot performed ground runs to test the variable pitch propeller. Finding the propeller functional, the pilot proceeded with the flight to George. The flight lasted approximately four hours and 25 minutes, with the oil pressure remaining at zero throughout the cruise. After landing in George, the oil level was again verified at 12 quarts.
The investigation
The investigation focused on the events leading to the engine failure, which occurred the following day during a ground run intended to diagnose the gauge issue. During this procedure, the engine seized. Investigators examined the cockpit oil pressure gauge and confirmed it was in serviceable condition. Furthermore, an inspection of the oil filter element and the oil pressure pump revealed no engine debris, suggesting that oil flow had ceased prior to the failure of the main bearings.
Findings
- The primary cause of the engine seizure was the lack of oil flow to the engine components.
- The pilot continued the flight despite a zero oil pressure indication, even though oil temperatures remained within normal ranges.
- The specific reason for the erroneous zero oil pressure reading could not be determined.
- The failure of the main bearings may have been caused by a period of engine operation without sufficient oil or the improper installation of the pressure relief valve.