Summary
The Federal Aviation Administration (FAA) proposes to supersede an existing airworthiness directive (AD), 98-18-12, applicable to certain Textron Lycoming reciprocating engines with certain Crane/Lear Romec "AN" rotary fuel pumps installed. That AD currently requires initial and follow-up torque check inspections of pump relief valve attaching screws. This proposal would require the same initial and follow-up torque check inspections of relief valve attaching screws, and add as a terminating action, replacement of the affected fuel pump at or before the overhaul interval, with a fuel pump having a new design valve housing. This proposal is prompted by the introduction of a new design pump relief valve housing and associated parts that provide enhanced resistance to fuel leakage, and the need for clarification of the requirements of the current AD. The actions specified by the proposed AD are intended to prevent rotary fuel pump leaks, which could result in an engine failure, engine fire, and damage to or loss of aircraft.