Agusta A109E crash near Boscombe Down Airfield, Wiltshire, United Kingdom

The helicopter landed after a routine flight during which a circuit breaker (CB) tripped. While an engineer was investigating the cause, the next flight crew noted a burning smell in the rear baggage bay during their walk-around checks. The operator’s investigation found evidence of a fire in the aft equipment bay , and a chaffed electrical cable. The cable was part of a design change that was made whilst the helicopter was on the UK military register before being approved by a Supplementary Type Certificate (STC) when the helicopter was transferred to the civil register. A protective strip should have been installed as part of the design change, but this was missing when the helicopter was examined after the incident. The strip would have prevented the cable from chaffing against the adjacent structure. Agusta A109E, G-ETPJ 01-21