I am more familiar with the Aircraft bending in the middle and twisting enough to cause large ripples in the Skin when lifting heavy loads on a single hook.

I have seen the Chinook put through her paces in far more dramatic maneuvers than the RAF display which at least tried for "smoothness and grace" as the display was planned and thought out ahead of time.

Our displays were unplanned and spontaneous when it became necessary to avoid riling the locals anymore than they seemed to be due to our presence.

For instance, I am quite sure the RAF Display never pulled up on the Lever until it drooped the Rotor system past he pointl the AC Generators dropped off line.:uhoh:

Yes Rigga, Self Tuning Vibration Absorbers if the memory isn't playing tricks, weighed a ton weight and the front of the aircraft appeared to have been built around them.

Nutloose

Agreed. Needed a crane to lift them onto the test bed. Incredibly efficient devices. We would place a glass of water on the top, the actuators would be stroking and the water wouldn't ripple.

Let's face it, if you tie two helicopters together, forcing them to fly in very close formation, there are bound to be problems. ;)

I was always suspicious of a design that sat the pilot on a big heavy block and let the aircraft vibrate around him on springs. :oh:

I guess the vibration reduction measures didn't work!

https://www.flightglobal.com/news/articles/boeing39s-helicopter-hat-trick-50347/

https://www.flightglobal.com/FlightPDFArchive/1998/1998%20-%200368.PDF

In the "Helicopter-Hat-Trick" article the guy says helicopter airframes will go forever if you repair/replace the broken parts.
This appears quite true, excepting if you don't find the problems or if cracks grow too quickly for you to find them!