Incident Summary
On 7 October 2001 at 0700Z, a Cessna 177 (registration ZS-NDE) was on a private local flight in the Upington district. The pilot returned to FAUP (Upington aerodrome) and selected gear down, but received no positive gear-down indication. Air traffic control informed the pilot that the landing gear was not fully extended. The pilot attempted to use the emergency gear extension system, but discovered it was inoperative due to a lack of hydraulic pressure. The pilot executed a landing with the gear in an unsafe position. On touchdown, the main landing gear collapsed while the nose gear remained extended. The aircraft skidded on the nose wheel and tail for approximately 300 meters before coming to rest to the left of runway 35. Damage was limited to the left wing-tip and tail.
Investigation Findings
Post-accident inspection revealed hydraulic fluid run-marks in the vicinity of the right-hand main gear wheel well. Further examination found that the left-hand rudder cable had been rubbing against and had chafed through one of the hydraulic pressure lines. This caused a hydraulic fluid leak, leading to total hydraulic system failure. The failure also rendered the emergency gear extension system unserviceable. The aircraft had accumulated 71.3 hours since its last mandatory periodic inspection (MPI), which was conducted on 9 October 2000 at 2947.0 airframe hours.
Probable Cause
The left-hand rudder cable had been in contact with and had chaffed through one of the hydraulic lines of the undercarriage system, resulting in hydraulic fluid loss and system failure.