Boeing Stearman 1B75A Ground Loop at Pilansberg Airport (ZS-LZZ)

Accident Overview and Aircraft Details On 7 January 2003, a Boeing Stearman 1B75A with registration ZS-LZZ was involved in an accident at Pilansberg Airport. The aircraft was operating a private flight from Rustenburg (FARG) to Pilansberg (FAPN). The pilot-in-command held a commercial license and had 9,512.6 total flying hours, including 73.6 hours on type. The aircraft's age was 61 years. ## Operational Sequence The pilot reported intermittent stiffness in the left wheel during taxi maneuvers. On the day of the accident, the aircraft was hand-moved from the hangar, with the left wheel moving freely. During the pre-takeoff power check, very positive brake pressure was required to hold the aircraft stationary. Intermittent resistance was experienced during the takeoff roll, but the aircraft accelerated normally and the takeoff was continued. ## Accident Event On landing on runway 05 at Pilansberg Airport, the left wheel locked. The aircraft veered sharply to the left, ground looped, and came to rest on its nose on the side of the runway. The accident occurred at 0546Z. ## Meteorological and Personnel Information Weather conditions were fine, with light and variable winds. There were two people on board, and no injuries or fatalities were reported. ## Maintenance and Probable Cause The last mandatory periodic inspection was certified on 25 May 2002 at 10,908.38 airframe hours, with 31.23 additional hours flown since. The pilot reported 66 landings between 18 December 2002 and the accident date. The investigation found that the brake master cylinder was malfunctioning by not releasing applied brake pressure back into the system, allowing the brake shoes in the drum brake system to remain in the activated position.