History of Flight
On 10 May 2015 at 0815Z, a pilot and passenger aboard a Yak-52, registration ZU-ULU, departed from Vereeniging Airport (FAVV) for a Visual Flight Rules (VFR) flight to Rand Airport (FAGM). The flight was uneventful, and the aircraft landed safely on runway 29. During taxi on taxiway 17, the pilot began a 90-degree left turn toward the hangars at approximately 15 knots when a sudden brake and steering failure occurred. After turning about 45 degrees, the aircraft veered off the taxiway line and headed toward the parking area. The sloping terrain caused the aircraft to accelerate uncontrollably for about 40 meters before colliding with a parked, unoccupied Piper PA-31 Chieftain (ZS-LKM) in front of hangar 12. The propeller struck the right-hand wing tip of ZS-LKM and came to rest below the right-hand horizontal stabilizer. The aerodrome rescue and fire fighting vehicles responded. No occupants or persons nearby were injured.
Investigation Findings
The pilot held a valid Private Pilot Licence with 750 total flying hours, including 34.5 hours on type, and was properly licensed for the flight. The aircraft had accumulated 850 total hours; its last annual inspection was on 24 April 2015 at 848 hours, with only 2 hours flown since. The investigation revealed that the aircraft experienced a hydraulic brake and steering failure during taxi, rendering the pilot unable to complete the left turn or brake. Disassembly of the left wheel showed destruction of the brake drum due to corrosion in an area inaccessible during annual inspection.
Damage to Aircraft
ZU-ULU sustained damage to the engine front, spinner, and one propeller blade broke off. ZS-LKM sustained damage to the right-hand wing tip, main landing gear door, and the right-hand side of the fuselage below the horizontal stabilizer.
Probable Cause
The aircraft experienced a sudden brake and steering failure due to the left hand brake failing and resulting in collision. A contributory factor was corrosion found in the brake drum in an area inaccessible during annual inspection.