This is a subject which has always interested me, so here goes.

I have some , quite a few, JR servos which are over 24 years old they still work perfectly.

My high operating time servos are JR 9411s. These are on the rudders of my original Bobcat (7 years old) which are gyro controlled so are always working. It is a demanding function and the servos originally spec' ed for the BobCat rudders by BVM, JR3421s , burned out quite quickly and JR recommend they NOT be used for gyro applications. After 250 flights the 9411s are still working absolutely perfectly so they stay in place till (if) they fail to so I can get SOME info. on servo lifetime.

I also remember reading comment on servo life by Curtis Youngblood. His opinion is that good servos last until the model crashes from some other cause. !

I have only ever had 3 servo failures on jet models, 1 4721 and 2 8411s all caused by prolonged stalling on ground test/set up. All 3 servos locked absolutely solid.

Might be worth adding that I always use powerful servos, which some might regard as overkill, to give the servos an easy life. always use a Hangar 9 digital load meter during set up to minimise current draw and always use voltage regulation at around 5.7 volts !

Coffee finished, over to you .

Regards,

David Gladwin.