What happened
On November 8, 2018, a Bombardier DHC 8-Q400, registration SP-EQL, was performing an approach to land at Kraków-Balice Airport (EPKK) when the crew identified a leak within the number 1 hydraulic system. Following consultation with the operator's Maintenance Coordination Centre and Operations Safety Department, the crew decided to divert the aircraft back to Warsaw-Okęcie (EPWA).
During the return flight, the crew executed the Quick Reference Handbook (QRH) checklist for "LOSS of ALL FLUID from No.1 HYDRAULIC SYSTEM." Due to the system failure, the aircraft was unable to utilize normal or anti-skid braking systems, necessitating the use of the emergency brake procedure. Additionally, the crew performed the "ABNORMAL FLAP LANDING" checklist, as the landing was conducted with flaps at setting 0. Because of the high approach speed (VREF) and the lack of standard braking capabilities, the crew declared an emergency landing. The aircraft landed safely at Warsaw-Okęcie without further incident.
The investigation
The PKBWL investigation focused on the source of the hydraulic fluid loss and the subsequent operational decisions made by the crew. The investigation examined the mechanical integrity of the hydraulic installation and the implementation of emergency procedures during the diversion and landing phases.