I just epoxied the servo to the wing as per directions this is a very safe way to do it, if the plastic is prepared properly. You pretty much gurantee a permant joint. As for needing to replace the servo one day, if you use a decent ball bearing servo of 60+ oz of torque you should be old and gray before you wear it out. Of course I could be wrong but we put alot of money and work into a plane and trust it all to the servos, receiver, and battey pack.