On the morning of the accident, the pilot woke at 0530 Central Summer Time (CSuT) and started duty at 0630. The pilot had undertaken an Instrument Flight Rules (IFR) Regular Public Transport (RPT) check flight in a Cessna 402 for 2.3 hours during the mid-morning on the day of the occurrence. The pilot's performance during the check flight was considered above average. The pilot was then tasked by the company for a Visual Flight Rules (VFR) charter flight in a Cessna 210. Towards the end of this substantial tour of duty, the pilot entered the Croker Island circuit for an approach to runway 31 at about 1806. During final approach, the pilot did not recall any auditory landing gear warnings, nor did he recall the status of the landing gear indicator lights. The pilot proceeded to land the aircraft with the landing gear retracted. This event occurred at approximately 1813 (CSuT). The pilot and five passengers were unharmed and evacuated the aircraft.
The pilot reported that he was fatigued during the flight and that the landing gear pump circuit breaker had popped on the final leg to Croker Island. The pilot recycled the landing gear pump circuit breaker and realised that the electric motor was still running. The pilot subsequently elected to pull the circuit breaker to prevent damage to the electric motor. This procedure was executed in accordance with the Cessna 210 Information Manual recommendation that when the hydraulic pump continues to run after gear cycle completion (up or down), the gear pump circuit breaker should be pulled out to shut off the hydraulic pump motor, thereby preventing damage to the pump and motor. The circuit breaker must be re-engaged prior to landing so that the landing gear can been extended (sections 3-20 & 7-12 of Cessna 210 Information Manual). On approach to Croker Island, the pilot selected the landing gear down but forgot to re-engage the landing gear pump circuit breaker. Consequently, the wheels did not deploy.
The pilot reported that the aircraft had sustained damage to the propeller and the underside of the aircraft. An initial engineering inspection revealed no apparent damage to the engine crankshaft or other engine components. A maintenance engineer from the company's contracted maintenance organisation found the landing gear handle in the fully extended position and the landing gear pump circuit breaker disengaged.
The pilot had accrued 2286.9 hours of flight time, of which 785.0 hours were on the Cessna 210. The pilot was considered as above average and very capable by both the chief pilot and the check-and-training officer. The pilot had flown five aircraft types in the week preceding the occurrence.
The maintenance release indicated no problems with the landing gear. The pilot reported that the Cessna 210 was well maintained and serviceable prior to flight.
The company did not have a documented procedure for the actions required when the landing gear hydraulic pump continues to run when the landing gear has been retracted. The Cessna 210 Information Manual recommends that when the hydraulic pump continues to run after gear cycle completion (up or down), the gear pump circuit breaker should be pulled out to shut off the hydraulic pump motor, thereby preventing damage to the pump and motor. The circuit breaker must be re-engaged prior to landing so that the landing gear can been extended (sections 3-20 & 7-12 of Cessna 210 Information Manual). The pilot reported that he was familiar with this procedure as annotated in the Cessna 210 Information Manual. The pilot also reported that the landing gear warning systems were tested and found to be fully functional prior to flight. These systems include the landing gear intermittent warning tone and gear indicator lights.
The pilot did not recall hearing any audio warning indicating that the gear had not extended until the aircraft was on the ground. In addition, the pilot did not recall the status of the landing gear indicator lights prior to landing. Finally, the pilot did not visually confirm the extension of the landing gear.
The pilot reported that he was very tired on the day of the occurrence and that he had been tired for some time leading up to the accident. The pilot's work/rest history for the 14 weeks before the accident was examined using a computerised fatigue algorithm developed by the Centre for Sleep Research, University of South Australia. The results indicated that the pilot was probably not suffering severely from cumulative fatigue on the day of the accident. On the day of the occurrence, however, the pilot reported feeling tired and he had been on duty for almost 12 hours before the accident. Moreover, he had been awake for almost 14 hours before the accident.
The pilot probably suffered from a transient fatigue related memory lapse where he forgot to re-engage the landing gear pump circuit breaker before landing and failed to visually check that the landing gear was down and locked.