Summary
The FAA proposes to adopt a new airworthiness directive (AD) for certain Model 767-400ER series airplanes; and Model 777-200 and - 300 series airplanes. This proposed AD would require, for certain airplanes, repetitive testing of the fill and safety fittings of the fire extinguishing bottles in the forward cargo compartment for leaks; and repetitive application of a corrosion inhibiting compound (CIC) or replacement of the fire extinguishing bottles with reworked fire extinguishing bottles, as necessary. For all airplanes, this proposed AD would require replacement of the fire extinguishing bottles with reworked fire extinguishing bottles, which would end the repetitive tests and CIC applications if applicable. This proposed AD is prompted by failure of the safety fittings for the fire extinguishing bottles. We are proposing this AD to prevent failure of the safety fittings for the fire extinguishing bottles due to corrosion, which could result in leakage of extinguishing agent. If a fire occurs in the cargo bay, the fire extinguishing bottles could have less than enough extinguishing agent to control a fire.