What happened
On the afternoon of 10 April 2025, a Jabiru SP with registration ZU-OIL was conducting a training flight from Wonderboom Aerodrome (FAWB) in Gauteng. The flight, operated under Part 1-41 regulations, included a flight instructor and a student pilot. After approximately 30 minutes of flight time, the crew returned to the aerodrome to perform touch-and-go landings on Runway 29.
During the landing circuit, the crew noticed a drop in engine oil pressure, though oil temperature remained stable. As the aircraft transitioned to the right base leg, the engine began running roughly before eventually stopping. The pilot declared a Mayday via the tower frequency. Being approximately 3 nautical miles from the runway threshold, the crew was forced to execute an emergency landing in a nearby field characterized by overgrown grass. Upon touchdown, the nose gear collapsed, causing the aircraft to nose over and come to rest in an inverted position. The aircraft sustained substantial damage, but there were no injuries to the occupants.
The investigation
SACAA AIID investigators examined the aircraft and the components involved in the engine failure. The investigation focused on the oil system and the replacement of flexible hoses. It was noted that the aircraft had not been flown for approximately 16 months prior to the accident.
Investigators inspected the oil hose connecting the oil filter to the oil cooler. They found that this specific hose had burst, which allowed engine oil to be pumped out of the system, leading to the loss of oil pressure and subsequent engine shutdown. The investigation also involved contacting the Original Equipment Manufacturer (OEM) of the failed hose to determine its suitability for aviation use.
Findings
- The primary cause of the engine stoppage was the burst oil hose located between the oil filter and the oil cooler.
- The hose was positioned extremely close to the exhaust assembly, approximately 30mm away, exposing it to intense heat. The protective heat sleeve did not cover the specific area where the hose attaches to the oil cooler.
- The replacement hose had been sourced from a wholesale hydraulic equipment store rather than an aviation-approved supplier.
- The OEM for the hose stated that the product was a multipurpose PVC hose not designed for aircraft or vehicle use, noting a maximum temperature limit of only 60 degrees Celsius.
Safety action
It is recommended that the Director of Civil Aviation publish guidance in the General Aviation Skywatch magazine. This guidance should emphasize the necessity of using only authorized hoses that meet specific maintenance requirements for non-type certified aircraft (NTCA). Maintenance personnel are advised to consult the aircraft or engine manufacturer if there is any uncertainty regarding the appropriate replacement parts for fluid applications.