Summary
We are revising an earlier proposed airworthiness directive (AD) for certain The Boeing Company Model 737-300, -400, -500, -600, - 700, -700C, -800, -900, and -900ER series airplanes. The NPRM proposed to require installing a new tail strobe light housing and a new disconnect bracket, and changing the wire bundles. The NPRM was prompted by a review of the tail strobe light installation, which revealed that the tail strobe light is not electrically bonded to primary structure of the airplane. This action revises the NPRM by adding, for certain airplanes, an inspection to determine if sealant is applied and corrective actions if necessary. We are proposing this supplemental NPRM (SNPRM) to prevent, in case of a direct lightning strike to the tail strobe light, damage to the operation of other critical airplane systems due to electromagnetic coupling and large transient voltages, and damage to the control mechanisms or surfaces due to a fire, which could result in loss of controlof the airplane. Since these actions impose an additional burden over that proposed in the NPRM, we are reopening the comment period to allow the public the chance to comment on these proposed changes.