The damage took place when the propeller blades were rotated and came into contact with afterbody bolts left in the wagon-wheel structure of both engines after completing AYB-1055.
The maintenance instruction manual does not state that the afterbody bolts should be removed immediately, but this critical step clearly should have been taken after completing the inspection.
All maintenance personnel received training on the proper steps to incorporate AYB-1055 and the importance of not leaving afterbody bolts in the wagon wheels after removing the afterbody.
They requested a caution be included to highlight the damage that can occur if the afterbody bolts are left in without the afterbodies being installed.
The turn occurred without incident, and, afterwards, as I have done countless times before, I went into the shop to update maintenance control and the maintenance action forms (MAFs) while the other two maintainers removed the balance gear and installed the propeller afterbody assemblies.
Within seconds of returning to my shop, the maintenance chief called, saying the afterbody fell off the aircraft.
I'm thankful that the flying afterbody didn't hit anyone or anything on the way down.