Question about a flap actuator

Howdy everyone, I am getting ready to install my flap actuator for good and I have a question. For giggles I plugged it into a battery and it just spun in circles. Later I discovered that if I kept the end from spinning the shaft would extend and contract. Is this correct???? Why wouldn't it just go out and in when power is applied?
Thanks
Brandon

flap actuator

You have nothing to worry about! It's working fine. A few years back, I had the same concern.

Jim Diehl
7a N891DD
Lock Haven, Pa

IIRC, this is why you need to safety-wire it per plans.

Think of a simple bolt and nut combination. Without touching the nut that is on the bolt, just spin the bolt. The result is that the nut will spin with the bolt and not move up or down the length ot the bolt.

However, if you were to hold the nut while spinning the bolt, the nut will move up/down the threaded section of the bolt.