What happened
On February 26, 2003, an Air Nostrum Bombardier DHC-8-315, registration EC-ICX, was performing a scheduled passenger flight from Ibiza to Palma de Mallorca. During the flight, the crew noticed a discrepancy in the hydraulic fluid levels between the two independent hydraulic systems. In an attempt to rectify this, the crew performed an unwritten, in-flight hydraulic fluid transfer procedure.
As the aircraft approached Palma de Mallorca for landing at 19:35 UTC, the crew was unaware that the aircraft's braking configuration had been compromised. Upon touchdown on runway 24R, all four wheels of the main landing gear were simultaneously blocked. This caused the aircraft to skid heavily along the runway, resulting in the four main tires bursting and significant abrasion of the wheel rims and brake components against the asphalt. The friction generated sparks, but no fire occurred. The aircraft came to a stop in the middle of the runway, and while there were no injuries among the 51 passengers and 4 crew members, the incident caused significant damage to the aircraft and required the temporary closure of the runway.
The investigation
The CIAIAC investigation focused on the mechanical state of the braking and hydraulic systems, as well as the crew's actions prior to landing. Investigators examined the antiskid control unit, the parking/emergency brake selector valve, and the hydraulic system architecture. The investigation also reviewed flight data from the Digital Flight Data Recorder (DFDR), which showed significant longitudinal deceleration during the landing roll.
Investigators also looked into the maintenance and operational procedures regarding hydraulic fluid management. It was discovered that the procedure used by the crew to transfer fluid between systems was not documented in the Quick Reference Handbook (QRH) or the Airplane Flight Manual (AFM). Furthermore, the investigation noted that the Cockpit Voice Recorder (CVR) data was unavailable because no measures were taken to prevent the automatic overwriting of the recording after the incident.