I have field public TimeSpan TimeSpanField in myClass. I create instance of the myClass and fill field. Next I want to serialize it to XML and deserialize back to the object. I Know that Microsoft have problems with TimeSpan serialization therefore I found the answer How to serialize a TimeSpan to XML and use it. 
ok! It works good. But How to make similar for public TimeSpan[] TimeSpanArrayField. the indexer(http://msdn.microsoft.com/en-us/library/6x16t2tx.aspx) in this case didn't help.   
Code forpublic TimeSpan TimeSpanField
    [XmlIgnore]
    public TimeSpan TimeSpanField;
    [Browsable(false)]
    [XmlElement(DataType = "duration", ElementName = "TimeSpanField")]
    public string TimeSpanFieldString
    {
        get
        {
            return XmlConvert.ToString(TimeSpanField);
        }
        set
        {
            TimeSpanField = string.IsNullOrEmpty(value) ?
                TimeSpan.Zero : XmlConvert.ToTimeSpan(value);
        }
    }