diff --git a/addons/mrp_operations/mrp_operations.py b/addons/mrp_operations/mrp_operations.py
index 890827c0e07..fe8456ddaa2 100644
--- a/addons/mrp_operations/mrp_operations.py
+++ b/addons/mrp_operations/mrp_operations.py
@@ -26,7 +26,6 @@ import time
 from datetime import datetime
 from tools.translate import _
 from datetime import timedelta
-from dateutil.relativedelta import relativedelta
 
 #----------------------------------------------------------
 # Work Centers
@@ -72,14 +71,13 @@ class mrp_production_workcenter_line(osv.osv):
                     res[op.id] = op.date_planned
         return res
     
- #   def onchange_get_date_end(self, cr, uid, ids, workcenter_id, date_planned, cycle, hour, context=None):
-    def onchange_get_date_end(self, cr, uid, ids, workcenter_id, date_planned, cycle, hour, context=None):
+    def onchange_get_date_end(self, cr, uid, ids, date_planned, cycle, hour):
         res = {'value':{}}
-        yo = cycle * hour
-        if date_planned and isinstance(date_planned, str):
+        cycle_per_hour = timedelta(hours=(cycle * hour))
+        if date_planned :
             date_planned = datetime.strptime(date_planned, "%Y-%m-%d %H:%M:%S")
-        date_planned_end = date_planned + timedelta(hours=yo)
-        res['value'] = {'date_planned_end': date_planned_end.strftime("%Y-%m-%d %H:%M:%S")}
+            date_planned_end = date_planned + cycle_per_hour
+            res['value'] = {'date_planned_end': date_planned_end.strftime("%Y-%m-%d %H:%M:%S")}
         return res
 
 #    def onchange_get_date_end(self, cr, uid, ids, date_planned, cycle, hour, context=None):
diff --git a/addons/mrp_operations/mrp_operations_view.xml b/addons/mrp_operations/mrp_operations_view.xml
index 32615bf5742..1da32d2e90d 100644
--- a/addons/mrp_operations/mrp_operations_view.xml
+++ b/addons/mrp_operations/mrp_operations_view.xml
@@ -75,7 +75,7 @@
             <sheet string="Work Orders">
                 <group col="4">
                     <field colspan="2" name="name"/>
-                    <field name="workcenter_id" on_change="onchange_get_date_end(date_planned, cycle, hour, context)"/>
+                    <field name="workcenter_id"/>
                     <field name="production_id" on_change="onchange_production_id(production_id)"/>
                     <field name="production_state"/>
                     <field name="sequence"/>
@@ -84,13 +84,13 @@
                 <page string="Information">
                     <group>
                         <group string="Planned Date">
-                            <field name="date_planned" on_change="onchange_get_date_end(workcenter_id, date_planned, cycle, hour, context)"/>
+                            <field name="date_planned" on_change="onchange_get_date_end(date_planned, cycle, hour)"/>
                             <field name="date_planned_end"/>
                         </group>
 
                         <group string="Duration">
-                            <field name="cycle"/>
-                            <field name="hour" widget="float_time"/>
+                            <field name="cycle" on_change="onchange_get_date_end(date_planned, cycle, hour)"/>
+                            <field name="hour" widget="float_time" on_change="onchange_get_date_end(date_planned, cycle, hour)"/>
                         </group>
                         <group string="Actual Production Date" >
                             <field name="date_start" readonly="1"/>