What happened
On March 25, 2009, a SATA Air Açores Dornier DO-228-202, registered CS-TGO, was operating a scheduled flight from Horta to Corvo Airport. The flight proceeded normally through the route, with favorable weather conditions and calm winds reported at the destination.
As the crew prepared for landing on runway 12 at Corvo Airport, they selected the landing gear down. Upon deployment, the NWS Bypass caution light and the Master Caution light illuminated on the instrument panel. To assess the operational issue, the crew requested permission to perform a holding pattern between the islands of Flores and Corvo. Following this assessment, the pilot requested a diversion to Lajes International Airport on Terceira Island to seek better technical and operational support. The crew subsequently declared an emergency due to a hydraulic failure. The aircraft landed safely at Lajes at 13:18 UTC without further incident.
The investigation
The investigation focused on the cause of the cockpit warnings and the subsequent hydraulic failure. Maintenance personnel inspected the aircraft on the ground at Lajes and identified a hydraulic leak in the landing gear extension line. Following the replacement of the faulty line and successful testing in accordance with the Aircraft Maintenance Manual (AMM), the aircraft returned to service and completed three subsequent flights that day without further issues.
Findings
- The primary cause of the incident was a hydraulic leak in the landing gear extension line that occurred when the crew deployed the gear for landing.
- The crew's decision to divert to Lajes was appropriate, as the airport provided the necessary technical assistance to resolve the mechanical failure.