airplanes

The following airplanes have odd things about them:

• Some Boeing 737-500s
  • I noticed this sign while flying on a U.S. airliner's Boeing 737-500. It was placed on the outside of the engine cowl.
    • CAUTION
      DO NOT OPEN FAN COWL UNTIL LEADING EDGE SLATS ARE RETRACTED AND DEACTIVATED
      SEE INSTRUCTIONS INSIDE DOOR
    • My question here is: are the instructions inside the cowl doors on how to retract and deactivate the leading edge slats? It may be that there was some kind of incident where someone opened the cowl with the slats still activated and they were ruined, so as a reminder the sign was placed there. But it makes you wonder if the the egg came before the chicken?