Airworthiness Directive · Amendment 39-16034 · Fuel
Boeing Model 737-300, -400, and -500 Series Airplanes Equipped With a Digital Transient Suppression Device (DTSD) Installed in Accordance With Supplemental Type Certificate (STC) ST00127BO
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.
We are adopting a new airworthiness directive (AD) for certain Boeing Model 737-300, -400, and -500 series airplanes. This AD requires revising the maintenance program to include new fuel system limitations for airplanes modified in accordance with STC ST00127BO. This AD also requires inspections and checks of the DTSDs and corrective actions, if necessary. This AD results from fuel system reviews conducted by the manufacturer. We are issuing this AD to prevent a potential of ignition sources inside fuel tanks, which, in combination with flammable fuel vapors, could result in a fuel tank fire or explosion and consequent loss of the airplane.
You are responsible for having the actions required by this AD performed within the compliance times specified, unless the actions have already been done.
Within 30 days after the effective date of this AD: Revise the maintenance program to incorporate the fuel system limitations specified in Section 10.1 of the Goodrich Instructions for Continued Airworthiness for the Transient Suppression Device Installation Applicable to Boeing 737-300, -400, & -500 Airplanes Supplemental Type Certificate—ST00127BO, Document T2007-0010-0101, Revision D, dated January 16, 2007.
Within 30 days after the effective date of this AD: Revise the maintenance program to incorporate the scheduled inspections/operational checks specified in Section 2.2.3 of the Goodrich Instructions for Continued Airworthiness for the Transient Suppression Device Installation Applicable to Boeing 737-300, -400, & -500 Airplanes Supplemental Type Certificate—ST00127BO, Document T2007-0010-0101, Revision D, dated January 16, 2007; except that the initial inspections/checks required by paragraphs (i), (j), and (k) of this AD must be done at the compliance times specified in those paragraphs. Repeat the inspections/checks thereafter at the applicable compliance times in the column, “Frequency,” of the table specified in Section 2.2.3 of the Goodrich Instructions for Continued Airworthiness for the Transient Suppression Device Installation Applicable to Boeing 737-300, -400, & -500 Airplanes Supplemental Type Certificate—ST00127BO, Document T2007-0010-0101, Revision D, dated January 16, 2007.
(i) Prior to the accumulation of 39,000 flight hours after modification in accordance with STC ST00127BO, or within 12 months after the effective date of this AD, whichever occurs later: Do an operational check of the DTSDs, in accordance with Section 2.2.3, “Scheduled Inspections/Operational Checks,” of the Goodrich Instructions for Continued Airworthiness for the Transient Suppression Device Installation Applicable to Boeing 737-300, -400, & -500 Airplanes Supplemental Type Certificate—ST00127BO, Document T2007-0010-0101, Revision D, dated January 16, 2007. If the DTSD fails the operational check, repair before further flight, in accordance with the section of the Goodrich Aircraft Maintenance Manual Supplement with Wiring Diagrams, 737-300/-400/-500 FQIS with Goodrich Digital Indicators and Transient Suppression Device, STC Number: ST00127BO, Revision 5, dated December 20, 2006, that corresponds to the operational check specified in Goodrich Instructions for Continued Airworthiness for the Transient Suppression Device Installation Applicable to Boeing 737-300, -400, & -500 Airplanes Supplemental Type Certificate—ST00127BO, Document T2007-0010-0101, Revision D, dated January 16, 2007.
(j) Prior to the accumulation of 4,000 flight hours after modification in accordance with STC ST00127BO, or within 6 months after the effective date of this AD, whichever occurs later: Do a general visual inspection for critical bond damage of the DTSD safe-side harnesses (critical bond damage includes measuring the bonding resistance across the ground strap and verifying the resistance is less than 2.0 milliohms), in accordance with Section 2.2.3, “Scheduled Inspections/Operational Checks,” of Goodrich Instructions for Continued Airworthiness for the Transient Suppression Device Installation Applicable to Boeing 737-300, -400, & -500 Airplanes Supplemental Type Certificate—ST00127BO, Document T2007-0010-0101, Revision D, dated January 16, 2007, which includes Items 5, 6, 7, and 8 of Table 6 in Section 10.1, “Fuel System Limitations.” If any damage is found, repair before further flight, in accordance with the section of the Goodrich Aircraft Maintenance Manual Supplement with Wiring Diagrams for 737-300/-400/-500 FQIS with Goodrich Aircraft Maintenance Manual Supplement with Wiring Diagrams, 737-300/-400/-500 FQIS with Goodrich Digital Indicators and Transient Suppression Device, STC Number: ST00127BO, Revision 5, dated December 20, 2006, that corresponds to the general visual inspection specified in Goodrich Instructions for Continued Airworthiness for the Transient Suppression Device Installation Applicable to Boeing 737-300, -400, & -500 Airplanes Supplemental Type Certificate—ST00127BO, Document T2007-0010-0101, Revision D, dated January 16, 2007.
(k) Prior to the accumulation of 24,000 flight hours after modification in accordance with STC ST00127BO, or within 12 months after the effective date of this AD, whichever occurs later: Do a general visual inspection for physical separation of the DTSD safe-side harnesses from other airplane wiring, hydraulic tubing, structure, control cables, and bleed air ducts, in accordance with Section 2.2.3, “Scheduled Inspections/Operational Checks,” of the Goodrich Instructions for Continued Airworthiness for the Transient Suppression Device Installation Applicable to Boeing 737-300, -400, & -500 Airplanes Supplemental Type Certificate—ST00127BO, Document T2007-0010-0101, Revision D, dated January 16, 2007. If any damage is found, repair before further flight, in accordance with the section of the Goodrich Aircraft Maintenance Manual Supplement with Wiring Diagrams for 737-300/-400/-500 FQIS with Goodrich Digital Indicators and Transient Suppression Device, STC Number: ST00127BO, Revision 5, dated December 20, 2006, that corresponds to the general visual inspection specified in Goodrich Instructions for Continued Airworthiness for the Transient Suppression Device Installation Applicable to Boeing 737-300, -400, & -500 Airplanes Supplemental Type Certificate—ST00127BO, Document T2007-0010-0101, Revision D, dated January 16, 2007.
After accomplishing the actions specified in paragraphs (g) and (h) of this AD, no alternative inspections/checks, inspection/check intervals, or CDCCLs may be used unless the inspections/checks, intervals, or CDCCLs are approved as an alternative method of compliance (AMOC) in accordance with the procedures specified in paragraph (m) of this AD.
Note 2: Notwithstanding any other maintenance or operational requirements, components that have been identified as airworthy or installed on the affected airplanes before the revision of the maintenance program, as required by paragraph (g) of this AD, do not need to be reworked in accordance with the CDCCLs. However, once the maintenance program has been revised, future maintenance actions on these components must be done in accordance with the CDCCLs.
