Nothing new about these fuselage cracks, but rather that they aren’t being caught in time.
A quick and dirty search of the Service Difficulty reports for users like Continental, United, US Air, American and Southwest shows over 260 SDRs of fuselage cracks from 2000 through this year.
Over 14 ADs have been issued since 2002 including; 2002-07-08, 2002-07-10, 2002-07-11, 2003-08-15, 2003-23-03, 2004-18-06, 2004-23-10, 2005-13-27, 2005-13-30, 2007-26-04, 2008-12-04, 2008-19-03, 2009-21-01 and 2010-01-09 affecting every model of the 737s from the 200s to the 900s (2008-12-04).
Worst yet, is the appearance that the chem.- milled sheet step-cracking problem has carried forward to the 757s with AD-2011-01-15.
Just plug in the AD numbers above into this AD search query for full details >
http://www.airweb.faa.gov/Regulatory_and_Guidance_Library/rgAD.nsf/MainFrame?OpenFrameSet