What happened
On August 26, 2018, a Cirrus SR22, registration N4927, was operating a private VFR flight from Samedan to Elba, Italy, carrying a pilot and two passengers. Approximately 11 minutes after departing Samedan, while cruising near the Maloja Pass at an altitude of roughly 12,000 feet, the aircraft suddenly began experiencing vibrations.
The pilot attempted to troubleshoot the issue by adjusting the power lever; however, all engine parameters remained within normal operating ranges. The vibrations did not intensify and actually diminished as the aircraft's airspeed was reduced. Due to the uncertainty regarding the source of the disturbance, the pilot notified Milano Information of potential engine problems and diverted the flight to Lugano, where the aircraft is based. The aircraft landed safely in Lugano approximately 30 minutes after the incident, with one passenger slightly injured.
The investigation
Investigators reviewed data from the pilot, passengers, radio communications with Air Traffic Advisory Service Milano Information and Lugano Tower, radar data, and the aircraft's engine monitoring system. Upon inspection following the landing, the crew discovered that a section of the left-side plastic landing gear fairing had broken off and was missing.
Subsequent testing, including a ground engine run and a test flight conducted two days later with the fairing secured, revealed no further vibrations or mechanical issues.
Findings
- The sudden vibrations experienced over the Maloja Pass were most likely caused by the loss of a piece of the landing gear fairing.
- While the pilot reported engine problems to air traffic control, the engine parameters remained normal, and the reduction in airspeed mitigated the vibrations, suggesting the issue was aerodynamic rather than mechanical.
- The specific cause of the fairing's failure could not be definitively determined, though investigators noted that fatigue in the plastic component was a likely contributing factor.