Airworthiness Directive · Amendment 39-22138 · Wings
The Boeing Company Airplanes
This AD applies to The Boeing Company Model 737-8 airplanes, certificated in any category, as identified in Boeing Special Attention Requirements Bulletin 737-57-1352 RB, dated February 1, 2021.
The FAA is adopting a new airworthiness directive (AD) for certain The Boeing Company Model 737-8 airplanes. This AD was prompted by a report that, during production, a small number of fasteners in certain locations of the center fuel tank were cap sealed on top of a black stripe of ink with a clear overcoat. This clear overcoat is not an approved surface for sealing and can potentially compromise sealant adhesion. Compromised sealant adhesion can, over time, affect the lightning-protection properties of the airplane. This AD requires preparation of the affected surface areas to ensure that there is adequate sealant adhesion, and complete encapsulation of the discrepant fastener locations with the approved production sealant. The FAA is issuing this AD to address the unsafe condition on these products.
Within 10 years after the date of issuance of the original airworthiness certificate or the original export certificate of airworthiness, do all applicable actions identified in, and in accordance with, the Accomplishment Instructions of Boeing Special Attention Requirements Bulletin 737-57-1352 RB, dated February 1, 2021, except as specified by paragraph (h) of this AD.
Note 1 to paragraph (g): Guidance for accomplishing the actions required by this AD can be found in Boeing Special Attention Service Bulletin 737-57-1352, dated February 1, 2021, which is referred to in Boeing Special Attention Requirements Bulletin 737-57-1352 RB, dated February 1, 2021.
As an option to the sealant application required by paragraph (g) of this AD, it is acceptable to remove the existing sealant and the black stripe of ink prior to reapplying a fastener seal. Remove existing sealant and black stripe of ink as follows:
(1) Remove existing sealant to expose the black stripe of ink.
(2) Remove existing black stripe of ink using aluminum oxide cloth or paper, 150 to 220 grit.
Note 2 to paragraph (h)(2): Take caution not to abrade through the existing oven cured BMS10-20 coating under the black stripe of ink. The BMS10-20 was previously applied during production.
(3) Touch up exposed aluminum with Alodine 600 (Type I, II, or III) or Bonderite M-CR 600 Aero (Type I, II, or III).
(4) Apply fastener seal (cap seal) with BMS5-45.
(5) Apply BMS10-20 Type II fuel tank coating to any exposed alodine/bonderite surfaces not covered by the fastener seal; it is acceptable to extend BMS10-20 Type II coating over fastener seal.
The aircraft, engines and makers this AD names, by the model designations in its text. A model listed here may still be outside the AD's serial ranges.
Aircraft
