http://www.pprune.org/rumours-news/4...-aircraft.html
read fantom's post #4
" Engineering experts, according to people familiar with the matter, continue to assess whether
large, upwardly curved panels attached to the wingtips of some American 767s
have caused or contributed to certain cracks discovered in a section of the
structural backbone of a few planes. Called winglets and installed on many
types of commercial and business jets, the additions are designed to
increase fuel efficiency. (Andy Pasztor, Wall Street Journal - 6/22)"