PREVENTIVE MAINTENANCE SERVICE OF AMBULANCES AND TRUCKS OF THE DIFFERENT HEALTH ESTABLISHMENTS (EE.SS) OF THE JURISDICTION OF THE CENTRAL HUALLAGA HEALTH SERVICES MANAGEMENT OFFICE. - PREVENTIVE MAINTENANCE SERVICE OF AMBULANCES AND TRUCKS OF THE DIFFERENT HEALTH ESTABLISHMENTS (EE.SS) OF THE JURISDICTION OF THE HUALLAGA CENTRAL HEALTH SERVICES MANAGEMENT OFFICE. (EXPIRED)