Summary
This document proposes the adoption of a new airworthiness directive (AD) that is applicable to certain Model 737-600, 737-700, 737-700C, 737-800, and 737-900 series airplanes. This proposal would require measuring the electrical resistance of the support bracket for the fire extinguisher bottle located in the left main landing gear wheel well to ensure that it does not exceed the maximum allowed resistance; and corrective actions, if necessary. This action is necessary to prevent high electrical resistance in the squib firing circuit, which could result in insufficient electrical current to fire the fire extinguisher bottle squib and discharge the fire extinguishing agent, which could lead to an uncontrolled engine fire. This action is intended to address the identified unsafe condition.