Airworthiness Directive · Amendment 39-17418 · Engine exhaust
The Boeing Company Airplanes
This AD applies to The Boeing Company Model 737-600, -700, -700C, -800, -900, and -900ER series airplanes; certificated in any category; line numbers 1 through 3028 inclusive.
We are adopting a new airworthiness directive (AD) for certain The Boeing Company Model 737-600, -700, -700C, -800, -900, and -900ER series airplanes. This AD was prompted by reports of damaged fire seals on the forward edge of the thrust reverser. This AD requires inspecting to detect damage to the upper fire seals on the forward edge of the thrust reverser, where the fire seal contacts the 12-o'clock engine strut, and for correct stiffness and vent holes, and doing corrective actions if necessary; and installing a bracket for the fire seal. We are issuing this AD to detect and correct damage to the fire seals, which could allow airflow into the engine fire zone and could degrade the ability to extinguish an engine fire.
Within 36 months after the effective date of this AD: Do a one-time general visual inspection of the left and right thrust reverser halves of each engine for damage to the upper fire seal, for stiffness of the upper fire seal, and for missing vent holes as applicable, in accordance with paragraph 3.B. of the Accomplishment Instructions of Boeing Special Attention Service Bulletin 737-78-1086, Revision 1, dated May 15, 2012, except as required by paragraph (h) of this AD.
(1) If, during the inspection required by paragraph (g) of this AD, no upper fire seal damage is found, and the fire seal has the correct stiffness: Before further flight, drill vent holes if they are missing, and install a new bracket behind the upper fire seal retainer, in accordance with paragraph 3.B. of the Accomplishment Instructions of Boeing Special Attention Service Bulletin 737-78-1086, Revision 1, dated May 15, 2012.
(2) If, during the inspection required by paragraph (g) of this AD, upper fire seal damage or insufficient fire seal stiffness is found: Before further flight, install a new upper fire seal, drill vent holes if they are missing, and install a new bracket behind the upper fire seal retainer, in accordance with paragraph 3.B. of the Accomplishment Instructions of Boeing Special Attention Service Bulletin 737-78-1086, Revision 1, dated May 15, 2012, except as required by paragraph (h) of this AD.
Where this AD refers to Boeing Special Attention Service Bulletin 737-78-1086, Revision 1, dated May 15, 2012, the following exceptions apply.
(1) In that service bulletin, where Note row (a) of the table shown in Figure 10 refers to “(a)”, it should instead refer to Note row (b).
(2) Figures 1 and 3 of this AD, titled “Fastener Removal of the Retainer Support on the Left (Right) Thrust Reverser Half,” have View B showing the top fastener in the center of three adjustable sustained preload (ASP) fasteners. That top fastener does not require removal in order to remove the retainer. The figures in this AD point to the correct information for those fasteners.
(3) Figures 2 and 4 of this AD, titled “Installation of the New Bracket behind the Retainer Support on the Left (Right) Thrust Reverser Half,” have View B showing the top rivet hole. That rivet hole is actually below the row of three ASP fasteners. The figures in this AD point to the correct information for those rivet holes.
