Summary
The FAA proposes to supersede an existing airworthiness directive (AD) that applies to certain Boeing Model 737-600, -700, and -800 series airplanes. The existing AD currently requires repetitive inspections to detect damage of the aft strut insulation blanket, and eventual replacement of the insulation blankets with new, improved blankets. This proposed AD would add airplanes to the applicability and require installation of a new heat insulation blanket and new cover plate on the left and right side engine struts. This proposed AD would not retain the requirements of the existing AD and would terminate the requirements of the existing AD. This proposed AD results from reports of damaged heat insulation blankets on the engine struts. We are proposing this AD to prevent exposure of the lower surface of the strut to extreme high temperatures, consequent creation of a source of fuel ignition, and increased risk of an uncontrollable fire and possible fuel tank explosion.