Airworthiness Directive · Amendment 39-15951 · Boeing Model 747 Airplanes
Boeing Model 747 Airplanes
Superseded. A later AD replaced this one: AD 2013-26-12. Comply with the one in force.
This AD applies to Boeing Model 747-100, 747-100B, 747-100B SUD, 747-200B, 747-200C, 747-200F, 747-300, 747-400, 747-400D, 747-400F, 747SR, and 747SP series airplanes, certificated in any category, as identified in Boeing Alert Service Bulletin 747-53A2478, Revision 1, dated March 27, 2008.
The FAA is superseding an existing airworthiness directive (AD), which applies to certain Boeing Model 747 airplanes. That AD currently requires repetitive inspections to detect evidence of wear damage in the area at the interface between the vertical stabilizer seal and fuselage skin, and corrective actions, if necessary. The existing AD also provides for an optional terminating action for the repetitive inspections. For all Boeing Model 747-100, 747-100B, 747- 100B SUD, 747-200B, 747-200C, 747-200F, 747-300, 747-400, 747-400D, 747-400F, 747SR, and 747SP series airplanes, this new AD requires repetitive inspections for wear damage and cracks of the fuselage skin in the interface area of the vertical stabilizer seal and fuselage skin, a detailed inspection for wear damage and cracks of the surface of any skin repair doubler in the area, and corrective actions if necessary. For airplanes on which the fuselage skin has been blended to remove wear damage, this new AD requires repetitive external detailed inspections or high frequency eddy current inspections for cracks of the blended area of the fuselage skin, and corrective actions if necessary. This AD results from reports of wear damage on airplanes with fewer than 8,000 total flight cycles. In addition, there have been three reports of skin wear damage on airplanes that applied Boeing Material Specifications 10-86 Teflon-filled coating (terminating action per the existing AD). We are issuing this AD to detect and correct wear damage and cracks of the fuselage skin in the interface area of the vertical stabilizer seal and fuselage skin in sections 46 and 48, which could cause in-flight depressurization 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.
For airplanes identified in Boeing Alert Service Bulletin 747-53A2478, dated February 7, 2002: Prior to the accumulation of 15,000 total flight cycles, or within 1,200 flight cycles after February 10, 2003 (the effective date of AD 2002-26-15), whichever occurs later, perform a detailed inspection to detect evidence of wear damage of the fuselage skin at the interface area of the vertical stabilizer seal and fuselage skin, per Boeing Alert Service Bulletin 747-53A2478, dated February 7, 2002.
(1) If no wear damage of the fuselage skin is detected or any existing blendout is within the structural repair manual (SRM) allowable damage limits: Repeat the detailed inspection at intervals not to exceed 6,000 flight cycles.
(2) If any wear damage of the fuselage skin is detected or any existing blendout exceeds the allowable damage limits specified in the SRM: Before further flight, repair the vertical stabilizer seal interface and refinish the skin with BMS 10-86 Teflon-filled coating, per Boeing Alert Service Bulletin 747-53A2478, dated February 7, 2002. Accomplishment of the repair and refinishing is terminating action for the repetitive inspections required by paragraph (f)(1) of this AD.
Note 1: For the purposes of this AD, a detailed inspection is defined as: “An intensive visual examination of a specific structural area, system, installation, or assembly to detect damage, failure, or irregularity. Available lighting is normally supplemented with a direct source of good lighting at intensity deemed appropriate by the inspector. Inspection aids such as mirror, magnifying lenses, etc., may be used. Surface cleaning and elaborate access procedures may be required.”
Refinishing the fuselage skin with BMS 10-86 Teflon-filled coating, prior to the effective date of this AD, per Boeing Alert Service Bulletin 747-53A2478, dated February 7, 2002, terminates the repetitive inspections required by paragraph (f)(1) of this AD.
For airplanes identified in Boeing Alert Service Bulletin 747-53A2478, dated February 7, 2002: Inspections and terminating action done before February 10, 2003, per Boeing Service Bulletin 747-53-2192, dated July 21, 1981, are acceptable for compliance with the corresponding actions required by paragraph (f) of this AD, provided BMS 10-86 Teflon-filled coating was used, and the new allowable damage limits specified in Boeing Alert Service Bulletin 747-53A2478, dated February 7, 2002, are met.
(i) Except as provided by paragraph (j) of this AD: At the applicable times specified in Table 1 of this AD, do the actions specified in paragraphs (i)(1) and (i)(2) of this AD, as applicable. Accomplishing the initial inspection specified in paragraph (i) terminates the requirements of paragraph (f) of this AD.
(1) For all airplanes: Do the actions specified in paragraphs (i)(1)(i) and (i)(1)(ii) of this AD, as applicable.
(i) Do repetitive external detailed inspections for wear damage and cracks of the fuselage skin in the interface area of the vertical stabilizer seal and fuselage skin, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 747-53A2478, Revision 1, dated March 27, 2008.
(ii) Where a skin repair doubler is present in the interface area of the vertical stabilizer seal and fuselage skin, do a detailed inspection for wear damage and cracks of the surface of the repair doubler.
(2) For airplanes that have reduced skin thickness in section 46 due to blending without reinforcement: Do repetitive external detailed inspections or high frequency eddy (HFEC) current inspections for cracks of the blended area of the fuselage skin, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 747-53A2478, Revision 1, dated March 27, 2008.
| Compliance time (whichever occurs later) | Threshold | Grace Period | Repeat interval (Not to exceed) |
|---|---|---|---|
| For actions required by paragraph (i)(1) of this AD | Prior to the accumulation of 20,000 total flight hours since the date of issuance of the original airworthiness certificate or the date of issuance of the original export certificate of airworthiness, or within 7,500 flight hours after the last inspection of this AD, whichever occurs later | Within 6,000 flight hours after the effective date of this AD | 7,500 flight hours. |
| For actions required by paragraph (i)(2) of this AD | Prior to the accumulation of 20,000 total flight cycles since the date of issuance of the original airworthiness certificate or the date of issuance of the original export certificate of airworthiness, or within 6,000 flight cycles after the initial blend, whichever occurs later | Within 1,000 flight cycles after the effective date of this AD | 1,200 flight cycles for external detailed inspection, or 6,000 flight cycles for HFEC inspection. |
If corrosion-resistant steel rubstrips are installed in the interface area of the vertical stabilizer seal and fuselage skin: Within the applicable compliance times specified in paragraph (i) of this AD, inspect the fuselage skin using a method approved in accordance with the procedures specified in paragraph (m) of this AD.
If no wear damage or crack is found in the fuselage skin (or skin repair doubler) during any inspection required by paragraph (i) of this AD: Before further flight, apply Boeing Material Specifications (BMS) 10-86 Teflon-filled coating in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 747-53A2478, Revision 1, dated March 27, 2008.
If any wear damage or crack is found in the fuselage skin (or skin repair doubler) during any inspections required by paragraph (i) of this AD: Before further flight, after the inspection required by paragraph (i), do the actions specified in paragraphs (l)(1), (l)(2), and (l)(3) of this AD, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 747-53A2478, Revision 1, dated March 27, 2008.
(1) Measure the depth of the wear and record the location.
(2) Repair any wear damage and any crack.
(3) Apply BMS 10-86 Teflon-filled coating.
