Thanks to a recent posting at Landings.com by a poster named Larry I can explain to you why the FAA grounded many of American Airlines MD-80 fleet over the last month.
First, the MD-80 series of airliners was initially produced by McDonnell-Douglas and production was continued by Boeing after they acquired McDonnell-Douglas in 1997. The planes were based on the DC-9 and succeeded by the Boeing 717. Production of all DC-9, MD-80, and Boeing 717 aircraft has ceased with the end of 717 production in May 2006. All of these aircraft are still operated by several major carriers including:
Delta: MD-88 / MD-90
AirTran: Boeing 717
The issue that grounded the MD-80 series of planes had to do with an FAA issued maintenance directive sent to the airlines over 1 year ago that directed the inspection of wire ties on all MD-80 series aircraft to insure 1 inch spacing. In the case of American Airlines, they measured and found the wire ties to be "within specification", but as you can clearly see below 1.5" is not 1" and the FAA grounded all of American Airlines MD-80's until the inspections were redone and corrected because their tolerance was +/- .125". Larry mentions that some of the aircraft came from the factory with wire ties spaced 4" to 6", but forgets to mention it was on "new" aircraft. Not aircraft with 20 years of use on them and multiple pressurization's.
The writer of the posting on Landings seems to believe that the FAA did this as a thumb in the eye to the airlines and congress because of recent congressional hearings on FAA inspections, and I partially agree with him. The point I think he misses is that most of the aircraft disasters in the last 10 years have been attributed to wiring that was degrading and with the average age of the U.S. commercial airline fleet rising preventative maintenance and inspection of wiring is beyond reasonable to insure the safety of the flying public. The FAA published an entire report on aircraft wiring practices in February of this year and cited the 1996 crash of TWA flight 800 off the coast of New York, the crash of Swissair flight 111 just southwest of Halifax, and numerous other in-flight/ground fires in MD-11's and MD-80's.
So in the end Larry is bitter and you are safe. It makes me feel much better.