Clanking Noise

[TotalBeginner]

Question:

After a late shift at EGSS. I've often walked past a lineup of parked A/C and always wondered what that strange clanking noise is that comes from the engines as they windmill in the breeze??

[catchup]

Fan blades touching each other, cause they are not stiff linked and have some gap in their root attachment and outer link.

regards

[ShyTorque]

Nah, the big ends 've gone.