What happened
On 7 July 2003, a Cessna 337C Super Skymaster, registration G-BCBZ, was performing a familiarisation flight at Gloucestershire Airport. The pilot, a Class Rating Examiner, was conducting the flight to prepare for a subsequent skill test for the aircraft owner. The flight included general handling manoeuvres and a touch-and-go landing on Runway 22.
Following a smooth touchdown, the pilot intended to retract the flaps to prepare for a rolling takeoff. Due to the aircraft's specific cockpit layout, the pilot accidentally moved the landing gear retraction lever instead of the flap lever. As the nose gear began to retract, the nose of the aircraft lowered, causing the propeller to strike the runway surface. The aircraft slid to a halt on the left side of the runway. There were no injuries to the two crew members or the single passenger on board, though the aircraft sustained damage to the nose landing gear, doors, lower nose panels, and the front engine and propeller.
The investigation
The investigation examined the cockpit ergonomics and the pilot's actions during the critical moments of the takeoff roll. It was noted that the landing gear lever was positioned on the left side of the throttle quadrant, while the flap lever was on the right. The pilot was also managing the mental workload of a short runway and the specific operational requirements of a centre-line thrust aircraft, specifically the need to increase power on the rear engine first.
Investigators looked into why the landing gear was able to retract while the aircraft was still in contact with the runway. While a 'weight on wheels' switch on the nose gear is designed to prevent retraction, it was surmised that the light load on the nose gear oleo may have bypassed the protection circuit. The main landing gear remained extended because the aircraft's weight exceeded the hydraulic power available for retraction, and the hydraulic pump, driven by the front engine, had been shut down by the pilot before the aircraft stopped.
Findings
- The primary cause of the accident was the inadvertent operation of the landing gear lever instead of the flap lever.
- Several contributing factors included the pilot's lack of familiarity with this specific aircraft type and the physical fatigue resulting from instructional duties.
- The pilot's focus on the short runway length and the necessity of managing the rear engine power contributed to the error.
- The cockpit configuration, with the gear and flap levers on opposite sides of the throttle quadrant, facilitated the mistake.