What is the Effect of Unsynchronized Propellers? A long time ago, I had the privilege of flying in 4 engine turboprop airplanes in which the props were 'synched'(blades rotating in same speed) which of course is necessary for smooth thrust.

However, one of the exercises we performed(as a military aircraft) was called a "crash and dash"; we dove as steep as we could until we could get as close as we could to the surface, then pull out of the dive and attempt to 'fly below' any surface radar that may be tracking us.

Every time we did this maneuver it threw the props out of 'synch' and cause the airframe to shudder violently. Anything that was literally not 'nailed down' was thrown through the cockpit or cabin.

My question is, what effect does this have on the airframe and does one of the events require an inspection, or shorten the check cycle?
I would agree with the other comments, in that I don't think the extreme buffeting could be caused by out-of-sync props. Maybe if you lost a chunk of a blade and you had out-of-balance props, but that's a bit different. Or if one of the props came WAY out-of-sync. But I know nothing of the Orion aerodynamics or engineering.

My twin experience has been more of the light piston and turboprop variety, but I can tell you that out-of-sync props produce a "whah whah whah" sound that will drive you absolutely bonkers. As soon as I was straight and level, I'd match rpms/prop pitch on my engines (or turn on the prop sync) to get rid of the noise. I never wanted to try it long enough, but apparently acoustic oscillation like that can cause serious fatigue. And I would imagine that long-term exposure can't be good for the airframe.