Incident Overview
On 24 May 2008 at 1930 UTC, a Cessna 208 Caravan I floatplane (registration G-MDJE) experienced an in-flight separation of the left float water rudder while flying at 1,200 ft overhead Partick, Glasgow. The aircraft was on a non-revenue commercial positioning flight from the River Clyde to Loch Lomond, with a crew of two and no passengers. Both pilots were uninjured, and the water rudder was later recovered from a garden without causing any ground injuries.
Sequence of Events
Shortly after reaching cruising altitude, the crew felt a vibration lasting approximately 10 seconds. The pilot conducted a visual inspection from the cockpit and observed that the left float water rudder was missing. The aircraft diverted to Glasgow Airport, where an uneventful landing was made.
Examination Findings
Post-incident examination revealed that the water rudder attachment post at the rear of the left float had been distorted, and a weld on the rudder pivot tube had failed, leading to the separation. The damage pattern was consistent with the water rudder having struck a submerged object prior to the flight. The aircraft had accumulated 85 hours since its last scheduled water rudder inspection, which is required every 100 hours. During these inspections, a liberal coating of grease is applied to the rudder mechanism to prevent corrosion, which likely obscured the presence of the damage during subsequent pre-flight checks.
Aircraft and Crew Information
The aircraft was a 2001 Cessna 208 Caravan I equipped with one Pratt & Whitney Canada PT6A-114A turboprop engine. The commander, aged 34, held a Commercial Pilot's Licence and had 4,615 total flying hours, including 6.5 hours on type. His flying experience in the last 90 days was 32 hours, and in the last 28 days, 6.5 hours.
Safety Actions
No specific safety recommendations were issued in the report, but the incident highlights the potential for hidden damage in water rudder mechanisms due to grease application during routine inspections.