I recall coming back from a night resupply to Nowzad in early Herrick days and finding the aircraft listed heavily to the right when we tried to land on one of the old spots.
I went off the back to locate the problem - which was a 2 and a half foot boulder jammed between the two front left wheels (jammed enough to stay in place for a 35 min vibrating recovery to BSN).
We ended up holding it on the back wheels whilst the engineers unscrewed the outer wheel.
Happy days.....