Background
On 10 May 2012, at 11:52 UTC, a Christen Industries Inc. A-1 Husky, registration I-ESML, was on a tourist flight under Visual Flight Rules (VFR). The aircraft had departed from Belluno airport and was planned to return there. On board were the pilot, a 55-year-old male with approximately 3100 total flight hours and valid medical and license, and one passenger. The aircraft's documents and maintenance were in order.
Event
While overflying an area used for model aircraft at reduced power, the pilot perceived an irregular engine operation, which he attributed to possible carburetor ice formation. He decided to perform a precautionary landing on the nearby occasional airstrip located on the slope of Col Fenilon-Monte Grappa (elevation 4330 feet). During the landing roll, the left main gear wheel encountered a depression in the terrain. This caused the left shock strut to collapse, resulting in the propeller contacting the ground. The aircraft sustained significant damage, but no injuries were reported. Weather information for the area was not available, but the general situation was compatible with localized cloudiness as stated by the pilot.
Examination
Inspection of the aircraft revealed breakage of the cable that forms the elastic bundle of the left gear shock absorber. The oscillating arm to which the elastic bundle is attached had displaced beyond its normal limit. The breakage zone of the cable showed fraying of strands and irregular breaks of the elastic elements, indicating an overstress failure due to excessive stretching.
Cause
The propeller contacted the ground due to the breakage of the elastic bundle of the left gear shock absorber. The elastic bundle broke because the oscillating arm experienced excessive displacement when the left wheel passed at high speed into a depression in the terrain. The wheel traversing the depression was attributable to a landing carried out in an unsuitable area of the airstrip.