Incident
On 26 November 2024, a Robinson R44 Raven II helicopter (registration ZS-RZK) departed from Mequatling Private Farm in the Free State province for a game culling operation. The flight was conducted under Part 91 of the Civil Aviation Regulations in visual meteorological conditions. A pre-flight inspection revealed no abnormalities.
En route, the passenger felt nauseated and requested a landing. The pilot landed the helicopter in a small clearing among bushes without shutting down the engine. The passenger disembarked quickly to distance himself from the rotating main rotor blades. As he turned, he noticed smoke emanating from the rear of the helicopter near the exhaust. He signaled to the pilot by pointing and shouting “fire”.
The pilot handed a fire extinguisher to the passenger and began the shutdown procedure. After shutting down, with the main rotor still rotating slowly, the pilot exited to assist. The fire extinguisher was depleted before the fire could be extinguished. The pair used bottled water and their jackets, but the fire spread and engulfed the helicopter, destroying it. Neither the pilot nor the passenger was injured.
Investigation
The investigation revealed that the helicopter was manufactured in 2008 and was equipped with the muffler and tailpipe shield kit (as per Service Bulletin SB-46) during manufacture. However, SB-46 compliance was not documented in the maintenance records. The kit was intended to reduce the risk of fire ignition when landing in dense dry grass. The attachment clamps at the mounting positions confirmed the kit was originally installed.
A review of the Pilot’s Operating Handbook showed Safety Tip 15: “Do not land in tall dry grass. The exhaust is low to the ground and very hot; a grass fire may be ignited.” Safety Notice SN-17 also warns against landing in tall dry grass. The pilot’s action violated this guidance.
The investigation noted previous similar occurrences involving Robinson R44 helicopters (ZS-REJ in 1997 and ZS-RFB in 2000) that were destroyed by grass fires after landing on tall dry grass. These prompted the manufacturer to issue SB-46 in 2002.
Findings
The pilot held a valid Commercial Pilot Licence and Class 1 medical certificate, with 3576.2 total hours (942 on type). The helicopter had a valid Certificate of Airworthiness and Certificate of Registration. The latest mandatory periodic inspection was conducted on 17 July 2024. The helicopter was serviceable at the time of the flight.
The muffler and tailpipe shield kit were installed during manufacture; therefore, SB-46 did not apply to this helicopter. Despite the kit, the hot exhaust ignited the tall grass, and the fire rapidly spread. The grass appeared green at landing, but it was still capable of ignition.
Probable Cause
The helicopter landed on a tall, grass-covered area after the passenger experienced motion sickness. The hot exhaust ignited the grass, and the fire spread quickly and engulfed the helicopter, destroying it.