Any advice for a fixing the nose gear door actuator cylinder seal which blew
  yesterday.
 
  How long to replace the seal do you think.
 
  Just wondering if it is worth completely replacing the whole assembly by the
  time I get the $8 seals out here, and then the cost of shipping, running the
  actuator up to the maintenance outfit and back, who have the equipment and
  expertise to replace the seals, hourly rates $60.  Reckon its cost effective
  to buy the whole assembly and replace it myself.
 

Dom,

 

Consider this strategy.  Buy both a new actuator and a seal kit.  Quickly replace the old cylinder with the new and go fly.  At your leisure, replace the seals in the old (even if only for the learning experience) and keep it on your "quick fix" shelf along with tubes, tires, main actuator seal kit and other handy items.

 

The door actuators are simpler in construction than the gear actuators and do not require the removal of the pipe-threaded fittings for disassembly.  Also, there is a hole thru the actuator shaft so you can put a pin through it to hold the shaft (and spring) while you loosen the rod end locking nut - just remember how many turns to remove the rod end.  Note also that the floating tube on the shaft is the up stop.  Circlip pliers will be required to remove retaining clip. Remember the orientation of the seals, especially the shaft seal.

 

Why should you get a new one and at least disassemble the old?  To check that the failure is not from "cocking" the actuator and scoring the cylinder walls - something that new seals may only temporarily resolve.