What aircraft was involved and where did it happen?

The accident on 2009-10-26 involved a R22 Beta II, registration I-ANSO, at Torri del Benaco (VR), IT.

What was the probable cause of the accident?

The investigation determined that the belt fragments from the transmission system suffered a tensile overload, and the aircraft's sudden loss of control and subsequent crash were linked to the mechanical failure of the transmission components.

Robinson R22 Helicopter Crashes into Lake Garda

A Robinson R22 Beta II helicopter crashed into Lake Garda, resulting in the deaths of both the pilot and a passenger.

What happened

On October 26, 2009, at approximately 13:00 UTC, an R22 Beta II helicopter, registration I-ANSO, was conducting a local VFR sightseeing flight over the Lake Garda region. The flight departed from Verona Boscomantico Airport with the pilot and one passenger on board.

At 13:01 UTC, the pilot contacted the Padova Flight Information Center (FIC) to report a position of 1,100 feet over the lake. Shortly thereafter, while flying in a straight line toward the north along the eastern coast of the lake at an altitude of approximately 500 feet, the aircraft suddenly entered a nose-down attitude. The helicopter plunged into the waters of Lake Garda near Torri del Benaco. The impact resulted in two fatalities, as both occupants died instantly. The aircraft was completely destroyed.

The investigation

The ANSV investigation focused on the mechanical state of the aircraft and the flight dynamics leading to the crash. Investigators examined the wreckage and recovered fragments of the V-belts used in the transmission system. Laboratory analysis was conducted to compare the recovered belt fragments (S/N 13350) with new reference belts (S/N A-95 and B-95).

Technical examinations included dimensional analysis, thermal exposure tests, thermogravimetric analysis (TG/DTA), and differential scanning calorimetry (DSC). The investigation also reviewed the aircraft's maintenance history, noting that while the 100-hour inspection had been completed in May 2009, the specific check for the lower pulley had not been performed during that interval. Furthermore, investigators analyzed the possibility of "mast bumping," a phenomenon where the main rotor strikes the mast, often induced by abrupt control inputs or low-load conditions.

Findings

The investigation identified that the recovered belt fragments (S/N 13350) exhibited different physical properties compared to new belts, including a lower weight and a higher Young's modulus, suggesting the material had hardened due to mechanical and thermal stresses during operation.
The morphology of the belt fractures was consistent with a tensile overload.
The pilot was operating the aircraft at a low altitude (500 feet) following the coastline, a flight profile that can increase the risk of mast bumping if abrupt maneuvers are performed under low-G conditions.
The aircraft's transmission relies on V-belts to connect the engine to the transmission; the failure of these components was a primary focus of the technical analysis.