Overview
On 28 November 2013, a serious incident occurred involving a Saab 2000 aircraft, registration HB-IZW, during flight level 110 over Muzzano, east of Lugano Regional Airport. The incident was caused by the complete failure of the beta feedback transducer (BFT), a component that measures propeller blade angle.
Aircraft and Engine System
The aircraft was a twin-engine turboprop Saab 2000. The right engine experienced a loss of control due to a detached contact terminal within the beta feedback transducer. This transducer is part of the propeller control system, which regulates propeller blade angle via the FADEC (Full Authority Digital Engine Control). The failure prevented accurate measurement of blade angle, leading to uncontrolled engine behavior.
Flight Sequence
The flight crew, consisting of a commander and a copilot, initiated a normal departure. During climb at flight level 110, the right engine began to behave erratically. The crew observed indications of loss of control and shut down the engine as a precautionary measure. The aircraft diverted to Milan Malpensa Airport, where it landed safely. No injuries were reported, and the aircraft sustained no damage.
Investigation Findings
The Swiss Transportation Safety Investigation Board (STSB) determined that the serious incident was caused by the complete failure of the beta feedback transducer, specifically due to a detached contact terminal. This failure resulted in the loss of control of the right engine, compelling the crew to shut it down. No other contributing factors were identified.
Meteorological Conditions
At the time of the incident, weather conditions were reported as generally good, with no adverse weather affecting the flight. Specific details from the source include a general weather situation and a weather report for Milan Malpensa, but no direct influence on the incident was noted.
Safety Recommendations
The STSB issued safety recommendations based on the investigation. However, the source does not specify the recommendations in this excerpt. The report emphasizes that the sole purpose of the investigation is accident prevention.