party b shall provide free periodic maintenance service forthe main engine of _________ for _________ year(s) after the receiving of the work by party a and send maintenance personnel every _________month(s) for performing maintenance. this contract has been executed by the parties as of the day and year first above written. party a:_________ party b:_________ by:_________ by:_________ address:_________ address:_________ date:_________ date:_________