What happened
On April 11, 2009, an AS202/15 Bravo, registration HB-HEM, departed from St. Gallen-Altenrhein airport for a local VFR flight. Shortly after takeoff from runway 28, the aircraft's climb performance noticeably degraded. At an altitude of approximately 30 meters, the engine began to sputter and eventually failed. The pilot was forced to perform an emergency water landing in Lake Constance, approximately 1 NM west of the airfield. The impact with the water was violent, causing the aircraft to strike the surface in a left-wing-low attitude. The pilot sustained serious injuries, and the aircraft was destroyed.
The investigation
Investigators examined the wreckage, which was recovered from about 90 cm of water. While the engine, carburetor, and fuel pumps were found to be in normal working order, a critical defect was discovered within the left fuel tank. The investigation focused on the fuel delivery system, specifically the suction pipe used to pump fuel from the tank. The aircraft's fuel tanks had been nearly full at the time of the accident, and the fuel quality was found to be satisfactory.
Findings
Technical analysis revealed that a bracket used to secure the suction pipe in the left fuel tank had rubbed through the pipe wall. This abrasion, combined with the presence of a rubber washer, significantly restricted the fuel flow, making it impossible to maintain sufficient engine power. Although the pilot had switched the fuel selector to the right tank and engaged the electric auxiliary pump in an attempt to restore power, the low altitude left insufficient time to rectify the fuel starvation. The investigation also noted that the right tank's suction pipe showed signs of abrasion but had not been breached.
Safety action
Following the investigation, an urgent safety recommendation was issued to ensure that aircraft with similar tank constructions are inspected for damaged suction pipes. In response, the European Union Aviation Safety Agency (EASA) issued airworthiness directives (AD 2009-0177 and later AD 2009-0233) to address the issue across similar AS202 models.