What happened
On 8 April 2022, a flight instructor and a student pilot departed Cape Town International Airport in a Piper PA-38-112 (registration ZS-AXE) for a training session at Diemerskraal Aerodrome. The flight, conducted under visual meteorological conditions, was intended for touch-and-go circuit training.
Upon arrival at the aerodrome, the crew encountered significant crosswinds. To demonstrate a crosswind landing technique, the instructor utilized a prolonged low-wing method, maintaining a specific bank angle and rudder input to stabilize the aircraft on final approach. During the subsequent touch-and-go maneuver, the engine began to surge and eventually lost all power at approximately 150 feet above ground level. With limited time to react, the crew performed a forced landing in an open field on a private farm.
The aircraft struck the uneven terrain, causing it to bounce multiple times before the nose gear collapsed. The impact resulted in substantial damage to the aircraft. While the student pilot was uninjured, the instructor sustained a back injury.
The investigation
An investigation by the SACAA AIID established that the crew had omitted several standard in-flight and approach checks, specifically regarding fuel system monitoring, due to a cockpit discussion regarding the prevailing weather. The investigation also noted that the crew had not changed the fuel tank selection during the flight.
Post-accident testing by the operator's safety team and investigators revealed that the engine failure was not caused by mechanical malfunction or fuel contamination. Instead, the investigation focused on the physical movement of fuel within the tanks during extreme maneuvers.
Findings
- The primary cause of the engine power loss was fuel unpotting, where the prolonged sideslip technique used to counter the crosswind caused the fuel to migrate away from the outlet point toward the left wingtip.
- This migration resulted in a total interruption of fuel flow to the engine.
- A contributing factor was the failure of the crew to adequately monitor or manage the fuel levels and system status during the approach.
- The investigation noted that this risk is not exclusive to the Piper PA-38-112, as similar fuel system architectures are found in aircraft such as the PA28.
Safety action
Following the accident, the operator temporarily grounded its fleet to rule out fuel contamination. While no contamination was found, aircraft of the same type as ZS-AXE remained grounded for further investigation into the fuel system's behavior during crosswind maneuvers.