AD 2009-20-11: Boeing Model 737-300, -400, and -500 Series Airplanes Equipped With a Digital Transient…

This AD applies to Boeing Model 737-300, -400, and -500 series airplanes, certificated in any category, equipped with a digital transient suppression device (DTSD) installed in accordance with Supplemental Type Certificate (STC) ST00127BO. Note 1: This AD requires revisions to certain operator maintenance documents to include new inspections. Compliance with these inspections is required by 14 CFR 91.403(c). For airplanes that have been previously modified, altered, or repaired in the areas addressed by these inspections, the operator may not be able to accomplish the inspections described in the revisions. In this situation, to comply with 14 CFR 91.403(c), the operator must request approval for an alternative method of compliance according to paragraph (m) of this AD. The request should include a description of changes to the required inspections that will ensure the continued operational safety of the airplane.