Incident Overview
On 18 June 2007 at 0915Z, a Robinson R22 helicopter (registration ZS-RUZ) departed Cape Town International Airport on a private flight to Wellington. The pilot, who held a private pilot license and had 174.5 total flying hours (all on type), intended to build hours toward a commercial license.
The initial part of the flight was uneventful. After approximately 15 minutes of cruising at 1 000 ft above mean sea level (AMSL) with an indicated airspeed of 80 kts, the helicopter suddenly began vibrating and yawing randomly, accompanied by a partial loss of power and subsequent loss of height. The pilot executed a successful autorotative landing on an open field in the Brackenfell area, approximately 8 nautical miles northeast of Cape Town International Airport.
Injuries and Damage
No injuries were sustained by the pilot, and the aircraft incurred no damage during the landing.
Investigation Findings
The helicopter was recovered by an approved aircraft maintenance organisation (AMO) for further investigation. Examination revealed that some of the left-hand magneto distributor drive gear teeth were sheared, causing a partial loss of engine power. The magneto was replaced with a serviceable unit, and the engine was ground-tested, performing satisfactorily in all respects.
Maintenance History
The last mandatory periodic inspection (MPI) prior to the incident was certified on 19 April 2007 at a total of 1 308.4 airframe hours. The aircraft had flown 94.5 hours since that inspection. According to available records, the AMO (No. 221) that certified the last MPI held a valid approval certificate issued on 31 December 2006 with an expiry date of 30 November 2007. The AMO was last audited on 30 November 2006, and no major deficiencies were found.