What happened
On 07 March 2010, a Piper PA28-180, registration ZS-PEV, was conducting a navigation training flight from Beaufort West Aerodrome toward Upington. While cruising at 7,500 feet, the aircraft's upper engine cowling suddenly split into two sections. The right portion of the cowling detached from the airframe and struck the windshield, causing the glass to crack and allowing debris to enter the cabin. The remaining left portion of the cowling stayed attached by a single latch but swung into the propeller's path, leading to further structural damage and a noticeable drop in engine power.
Recognizing the emergency, the pilot initiated a descent and performed an emergency landing in an open field on a nearby farm. During the landing maneuver, the aircraft struck a perimeter wire fence, resulting in minor structural damage to the airframe and propeller. There were no injuries to the two occupants on board.
The investigation
SACAA AIID investigators examined the aircraft and the circumstances surrounding the pre-flight activities. The investigation focused on the mechanical failure of the cowling and the pilot's actions prior to departure. Evidence suggested that during the pre-flight inspection at Beaufort West, an attempt was made to remove the upper engine cowling to replenish engine oil. Although the pilot reported that the cowling was secured before takeoff, the investigation found that the cowling was likely not properly seated or fastened.
Findings
- The primary cause of the incident was the pilot's failure to properly secure the engine cowling following an attempt to remove it during pre-flight checks.
- The cowling was likely unseated or improperly fastened, causing it to flap in the slipstream and eventually disintegrate under aerodynamic pressure.
- The loss of engine power was a secondary effect caused by the left side of the cowling striking the propeller.
- The pilot's attempt to remove the cowling was unnecessary, as a quick-release access door was available for oil replenishment.
- Conflicting statements were noted between the training organization and the flight crew regarding the exact nature of the pre-flight assistance provided.