AD FAA-2012-1077

We are adopting a new airworthiness directive (AD) for certain Embraer S.A. Model ERJ 170 and ERJ 190 airplanes. This AD was prompted by a report that high rate discharge (HRD) bottle explosive cartridges of a cargo compartment fire extinguisher system were swapped between the forward and aft cargo compartments. Additional investigation also revealed the possibility of swapping between the electrical connectors of the HRD and low rate discharge (LRD) bottles, and a rotated installation of the HRD bottle. Improper assembly of the fire extinguishing bottle might cause the extinguishing agent to be discharged toward the unselected cargo compartment rather than toward the cargo compartment with fire. This AD requires an inspection of the HRD bottle for correct installation and to determine if the pressure switch is in the correct position, and re-installation if necessary; an inspection of the HRD and LRD bottle discharge heads to determine the part number, and replacement if necessary; and, for certain airplanes, an inspection to identify the HRD and LRD bottle electrical connectors, and relocation if necessary. We are issuing this AD to prevent the inability of the fire extinguishing system to suppress fire.