What happened
On July 24, 2008, a Cessna 172, registration CS-AHX, departed from Portimão Airport to perform a specialized advertising banner towing mission along the Algarve coast. The flight, operated by AeroVip Lda, was flying at approximately 800 feet altitude.
While operating approximately 2 nautical miles north of Faro Airport, the pilot detected a significant loss of engine power. This was accompanied by an indication of low fuel pressure in the engine'-s fuel delivery lines. Unable to maintain altitude, the pilot declared an emergency and requested an approach to runway 10 at Faro. To avoid flying over the city of Faro, the pilot opted for a precautionary landing on runway 10, despite encountering a 16-knot tailwind. The pilot successfully released the advertising banner and landed the aircraft safely at 14:42 UTC. The pilot sustained no injuries.
The investigation
Following the incident, maintenance personnel inspected the engine and identified a fracture in the fuel delivery tube supplying cylinder number 4. The investigation revealed that the fracture occurred near the injector connection. Further examination showed that the tube had been rubbing against an alternative engine air intake line, causing localized wear.
Investigators noted that while the fuel lines were secured at their ends, they lacked intermediate supports. This configuration allowed the lines to vibrate significantly during engine operation. The investigation also noted that a similar failure had occurred on the fuel line for cylinder number 3 just eleven days prior to this event.