Event Description
On 14 August 2004 at 10:40 local time, an Agusta A109 AII helicopter, registration I-DPCA, was conducting a transfer flight from Caiolo (Sondrio) to the Elilario base in Colico. The flight was part of a post-maintenance acceptance check involving on-board instrument verification. While flying at approximately 1,000 feet above ground level over a sparsely populated agricultural area near S. Pietro Berbenno (SO), the helicopter experienced an uncommanded loss of the right rear emergency exit door. A subsequent low-level search using the onboard GPS did not locate the missing component.
Aircraft and Maintenance Background
The helicopter, manufactured by Agusta in 1985, was a four-bladed passenger transport model with a maximum takeoff weight of 2,600 kg and a cruising speed of 120 knots. It was powered by two Detroit Diesel Allison 250-C20B engines. Registration occurred in 1986, and the airworthiness certificate was valid at the time of the event. The last periodic inspection had been performed on 12 August 2004, with zero flight hours accumulated since then. The operator was Compagnia Aeronautica Italiana SpA. Three persons were on board: two pilots and one technician.
Analysis and Findings
Examination of the remaining door structure revealed that the seals were correctly installed and the hinge pin receptacles on the sliding door frame showed no damage. The emergency exit door is secured by two fixed pins on its upper edge that engage corresponding holes in the door frame, and two lateral pins operated by emergency handles located inside and outside the passenger door. The closing mechanism includes a locking safety feature achieved by off-center positioning of the pins via spring preload.
This locking mechanism had previously been identified as potentially inadequate by Agusta, leading to the issuance of Mandatory Technical Bulletin 109-95 on 28 February 1994, later mandated by Airworthiness Directive RAI 94-71. That bulletin, prompted by a prior in-flight loss of the same component, required verification of correct handle position and braking, and proper engagement of the locking pins. It also mandated inspection of the braking system per specification QQ-W-343, replacement of handle covers with transparent ones, and application of warning labels. The maintenance organization, Elilario, had complied with the bulletin, as evidenced by the Certificate of Release to Service issued on 12 August 2004.
Although the missing door was not recovered, the investigation concluded that the loss likely resulted from an accidental rotation of the emergency handle. The rotation may have been caused by normal in-flight vibrations and facilitated by handle braking that did not meet the required technical standards.