Airworthiness Directives; Boeing Model 737-600, -700, and -800 Series Airplanes

This amendment adopts a new airworthiness directive (AD) that is applicable to certain Boeing Model 737-600, -700, and -800 series airplanes. This action requires a test of the squib circuit ground studs of the engine fire extinguisher bottles to measure the resistance, and repair or replacement of the ground stud with a new ground stud, if necessary. This amendment is prompted by reports of improper grounding of the squib circuit. Such a condition would prevent the engine fire extinguisher bottle from discharging when commanded, which could result in the inability to extinguish an engine fire.