A Saab 340A passenger plane, registered LV-BMD, sustained damage in a taxiway excursion accident at Mendoza-El Plumerillo Airport, MD (MDZ), Argentina. There were no injuries among the 30 passengers and three crew members. SOL L¡neas A‚reas flight 5420 was taxiing for takeoff at Mendoza-El Plumerillo Airport when the crew lost directional control of the aircraft. The airplane exited the taxiway and came to rest on rough terrain. Propeller blades of engine no. 1 were damaged, with shrapnel causing a 5 cm long hole in the fuselage. Aviation sources in Argentina reported in March 2013 that the airplane was considered damaged beyond economical repair. Conclusions: (translated from Spanish) While taxiing to the holding point of the runway in use, the crew of flight 8R5420 lost directional control and departed the taxiway, which resulted in the impact of the aircraft with objects on the ground. This was due to a combination of the following factors: – The electric pump which controls fluid pressure in the hydraulic system was not operational, generating a deficit of fluid pressure in the hydraulic system. – The low fluid pressure warning in the hydraulic system was not recognized by the crew. – The crew could not control the path of the aircraft due to the unavailability of nose wheel steering. – The persistence of an informal practice among the crews of the operator on the operation of the hydraulic system, contrary to the concept of operation of the hydraulic system established by the manufacturer. – The lack of detection of the informal practice on the operation of the hydraulic system by the operator’s safety monitoring mechanisms.