the faa said bill voss , president of the flight safety foundation .
 
as the nation 's planes age , more jets could cause concern and require inspection for such fatigue cracks .
 
jets that have accumulated many flight cycles are apparently more likely to develop the sort of fatigue cracks that may have caused the tear in the skin of the southwest 737 - 300 last week .
the federal aviation administration order will cover some 737 - 300s , 737 - 400s and 737 - 500s , models of the popular jet built in the 1980s and 1990s .
fatigue cracks found in three other southwest airlines jet that suffered a 5 - foot tear in its roof on friday in a search for possibly dangerous cracks .
eighty of the planes are in service in the united states , most of them for southwest airlines .
although the number of jets affected by the order is small , some aviation safety experts said the incident is shining a new light onto aging aircraft safety .