The ripples in the fuselage are caused by shear loads between the tail and C of G or undercarriage due to turbulence or heavy landings. The skin stretches are the moment of tension and deforms leaving a permanent wrinkle.
Each skin dent/buckle is recorded (most of which you'd never be able to find!) and must remain within certain limits.
The wrinkles disappear in-flight when the a/c is pressurised. It is obviously more common on the longer length 737 models.
|