What happened
On 27 May 2012, a Bell 206B helicopter, registration ZS-HRZ, departed Grand Central aerodrome for a private flight to the Limpopo province. During the initial takeoff attempt, the pilot noticed a "Low RPM" warning and subsequently landed the aircraft to offload one passenger and some baggage to reduce weight.
Following this, the pilot attempted a second departure, notifying air traffic control of a power-related issue and an intention to fly a single circuit. While established on a left downwind for runway 3/5, the pilot reported experiencing power loss and requested to return to the aerodrome. Shortly after this transmission, the helicopter struck a concrete palisade fence at an office park in Portland Park, Midrand, before crashing into a tree. The impact caused extensive damage to the aircraft and the perimeter fence. Both occupants sustained serious back injuries.
The investigation
SACAA AIID investigators examined the wreckage and the engine, an Allison 250-C20J. Laboratory testing of the engine at a certified facility found no mechanical failures or defects that would have prevented normal operation; the engine passed all functional bench tests. The investigation also confirmed that the fuel shut-off valve was in the full open position at the time of impact and that the aircraft had sufficient fuel.
Regarding the airframe, investigators confirmed that control continuity was intact prior to impact and that the damage to control surfaces was a result of the impact forces. The investigation also noted that the pilot had very limited experience on this specific helicopter type, with only 21.4 total hours on the model, much of which was conducted under instruction.
Findings
- The pilot allowed the main rotor RPM to decay and failed to take corrective action before the collision.
- The pilot failed to perform a precautionary landing after first encountering the power issue, choosing instead to continue with a second takeoff attempt.
- There was a lack of proper flight planning, specifically the absence of weight and balance calculations prior to the flight.
- The pilot lacked sufficient familiarity with the Bell 206B type.
- The pilot did not obtain an official weather report for the intended flight.