Summary
This document proposes to adopt a new airworthiness directive (AD) that would apply to all U.S. owners and operators of aircraft equipped with Precise Flight, Inc. Model SVS III standby vacuum systems installed in accordance with the applicable supplemental type certificate (STC) or through field approval. The proposed AD would require incorporating revised operating limitations for the affected standby vacuum systems into the airplane flight manual (AFM), and repetitively inspecting the push-pull cable, vacuum lines, saddle fittings, and shuttle valve for correct installation and damage (wear, chafing, deterioration, etc.). The proposed AD would also require immediately correcting any discrepancy found and conducting a function test of the vacuum system after the inspections. This AD results from reports of shuttle valve failure and standby vacuum system malfunction on aircraft. The actions specified by the proposed AD are intended to detect and correct problems with the standby vacuum system before failure or malfunction and to provide operating procedures for the pilot regarding the use and limitations of this system.