What happened
On 24 May 2008, a Cessna 208 Caravan I (floatplane), registration G-MDJE, was conducting a non-revenue commercial air transport positioning flight from the River Clyde to Loch Lomond. While cruising at 1,200 ft over Partick, Glasgow, the pilot felt a vibration lasting roughly 10 seconds. Upon performing a visual inspection from the cockpit, the pilot discovered that the water rudder on the left float had detached from the aircraft.
The pilot subsequently diverted the aircraft to Glasgow Airport, where the landing was completed without further incident. No injuries were reported among the two crew members.
The investigation
Investigators examined the aircraft's left float and identified that the attachment post at the rear of the float had been distorted. Furthermore, a weld on the rudder pivot tube had failed, which led to the separation of the rudder. The nature of the damage to the post was consistent with the rudder having collided with a submerged object. The detached rudder was later located in a garden on the ground.
Findings
- The water rudder separated due to a failed weld on the pivot tube and a distorted attachment post.
- The damage pattern suggested the rudder had struck a submerged object.
- The aircraft had been operating for 85 hours since its last scheduled water rudder inspection, which is required every 100 hours.
- The application of a heavy layer of grease to the rudder mechanism to prevent corrosion likely hid existing damage from being detected during the most recent pre-flight inspections.