Sorry about the above entered in error!!!!!!. .. .A captain can refuse to take an unserviceable aircraft.. .. .If he declines to take a serviceable aircraft which is within the MEL but has restrictions with which he is unhappy he is going to face the chief pilot particularly if 150 pax are left in the terminal. . .. .If he refuses to take a an aircraft which has been declared serviceable by engineering and is so ( a worn within limits tyre might be an example) he will find his career path leads over the nearest cliff.