Summary
This document proposes the supersedure of an existing airworthiness directive (AD), applicable to certain McDonnell Douglas Model MD-11 and MD-11F series airplanes, that currently requires opening the circuit breaker of the pneumatic sense line heater tape, installing an inoperative ring, and coiling and stowing the electrical wire to the circuit breaker of the pneumatic sense line heater tape. That AD also provides for an optional inspection, which, if accomplished, constitutes terminating action for deactivation of the pneumatic sense line heater tape. This proposal is prompted by the FAA's determination that the one-time optional terminating inspection in the existing AD does not adequately detect chafing, electrical arcing, or inadequate clearance of the subject area. The actions specified by the proposed AD are intended to detect and correct such inadequate clearance, which could result in a hole in the fuel feed pipe caused by electrical arcing, and consequent fuel leakage and possible ignition of the fuel vapors. This action would require repetitive inspections of the subject area and corrective actions, if necessary, and would provide for an optional terminating modification(s) for the repetitive inspection requirements.