What happened
On 17 May 2004, a Grob 115A aircraft, registration EI-CAC, was conducting a routine private training flight. During the flight, the pilot detected a strong odor of fuel fumes within the cockpit. Taking immediate precautionary action, the pilot diverted the aircraft to Kilrush Airfield and performed a safe landing. There were no injuries to the pilot and no damage was sustained by the aircraft during the landing.
The investigation
Following the landing, a licensed engineer inspected the aircraft and identified a leak in the fuel feed hose that connects the fuel selector valve to the rear of the firewall. The investigation established that the left pedal rudder control rod had been rubbing against a flexible fuel hose, eventually wearing through the material and allowing fuel to escape into the cockpit area.
Further inspections by the operator revealed that this was not an isolated incident. The operator found identical wear patterns on the fuel hoses of two other Grob 115A aircraft, registration EI-CAD and G-BYFD. In all identified cases, the hoses were found to be too short, causing them to interfere with the rudder control linkage. To resolve the issue, the operator began using hoses that were 20 mm longer than the manufacturer's specified length of 1,120 mm to prevent contact with the rudder mechanism.
Findings
- The fuel leak originated from a damaged hose in the cockpit area.
- The primary cause of the leak was that the fuel hose was overdue for replacement according to the manufacturer's maintenance schedule.
- The physical cause of the wear was the contact between the rudder pedal crossbar and the fuel hose.
- While local maintenance regulations (LAMS) required pressure testing every 36 months after an initial 72-month test, the manufacturer's requirements mandated a full replacement every five years.