Airworthiness Directive · Amendment 39-18226 · Air conditioning
The Boeing Company Airplanes
Superseded. A later AD replaced this one: AD 2015-21-11. Comply with the one in force.
This AD applies to The Boeing Company airplanes, certificated in any category, as identified in paragraphs (c)(1) and (c)(2) of this AD.
(1) Model 737-100, -200, -200C, -300,—400, and -500 series airplanes, as identified in Boeing Special Attention Service Bulletin 737-21-1164, Revision 2, dated August 23, 2013.
(2) Model 737-600, -700, -700C, -800, -900, and -900ER series airplanes, as identified in Boeing Special Attention Service Bulletin 737-21-1165, Revision 3, dated July 16, 2014.
We are superseding Airworthiness Directive (AD) 2012-19-11 for certain The Boeing Company Model 737 airplanes. AD 2012-19-11 required incorporating design changes to improve the reliability of the cabin altitude warning system by installing a redundant cabin altitude pressure switch, replacing the aural warning module (AWM) with a new or reworked AWM, and changing certain wire bundles or connecting certain previously capped and stowed wires as necessary. For certain airplanes, AD 2012-19-11 also required prior or concurrent incorporation of related design changes by modifying the instrument panels, installing light assemblies, modifying the wire bundles, and installing a new circuit breaker, as necessary. This AD was prompted by the report of a flightcrew not receiving an aural warning during a lack-of-cabin pressurization event. We are issuing this AD to prevent the loss of cabin altitude warning, which could delay flightcrew recognition of a lack of cabin pressurization, and could result in incapacitation of the flightcrew due to hypoxia (a lack of oxygen in the body), and consequent loss of control of the airplane.
This paragraph restates the actions required by paragraph (g) of AD 2012-19-11, Amendment 39-17206 (77 FR 60296, October 3, 2012), with revised service information. Within 72 months after November 7, 2012 (the effective date of AD 2012-19-11), install a redundant cabin altitude pressure switch, replace the aural warning module (AWM) with a new or reworked AWM, and change certain wire bundles or connect certain capped and stowed wires, as applicable, in accordance with the Accomplishment Instructions of the applicable service information in paragraphs (g)(1) and (g)(2) of this AD; except as provided by paragraph (k)(1) of this AD.
(1) Boeing Special Attention Service Bulletin 737-21-1164, Revision 1, dated May 17, 2012; or Boeing Special Attention Service Bulletin 737-21-1164, Revision 2, dated August 23, 2013 (for Model 737-100, -200, -200C, -300, -400, and -500 series airplanes). As of the effective date of this AD, use Boeing Special Attention Service Bulletin 737-21-1164, Revision 2, dated August 23, 2013, for the actions specified in paragraph (g) of this AD.
(2) Boeing Special Attention Service Bulletin 737-21-1165, Revision 1, dated July 16, 2010, as revised by Boeing Special Attention Service Bulletin 737-21-1165, Revision 2, dated April 30, 2012; or Boeing Special Attention Service Bulletin 737-21-1165, Revision 3, dated July 16, 2014 (for Model 737-600, -700, -700C, -800, -900, and -900ER series airplanes). As of the effective date of this AD use Boeing Special Attention Service Bulletin 737-21-1165, Revision 3, dated July 16, 2014.
This paragraph restates the concurrent actions required by paragraph (h) of AD 2012-19-11, Amendment 39-17206 (77 FR 60296, October 3, 2012), with revised service information. For airplanes identified in Boeing Alert Service Bulletin 737-31A1325, dated January 11, 2010 (for Model 737-100, -200, -200C, -300, -400, and -500 series airplanes); and Boeing Alert Service Bulletin 737-31A1332, Revision 3, dated March 28, 2012 (for Model 737-600, -700, -700C, -800, -900, and -900ER series airplanes); except as provided by paragraph (i) of this AD: Before or concurrently with accomplishment of the actions specified in paragraph (g) of this AD, as applicable, modify the instrument panels, install light assemblies, modify the wire bundles, and install a new circuit breaker, in accordance with the Accomplishment Instructions of the applicable service information in paragraphs (h)(1) and (h)(2) of this AD; except as provided by paragraph (k)(2) of this AD.
(1) The service information for Model 737-100, -200, -200C, -300, -400, and -500 series airplanes as identified in paragraphs (h)(1)(i), (h)(1)(ii), and (h)(1)(iii), of this AD. As of the effective date of this AD, use Boeing Alert Service Bulletin 737-31A1325, Revision 2, dated June 5, 2014 (for Model 737-100, -200, -200C, -300, -400, and -500 series airplanes), for the actions specified in paragraph (h) of this AD.
(i) Boeing Alert Service Bulletin 737-31A1325, dated January 11, 2010.
(ii) Boeing Alert Service Bulletin 737-31A1325, Revision 1, dated July 5, 2012.
(iii) Boeing Alert Service Bulletin 737-31A1325, Revision 2, dated June 5, 2014.
(2) Boeing Alert Service Bulletin 737-31A1332, Revision 3, dated March 28, 2012; or Boeing Alert Service Bulletin 737-31A1332, Revision 4, dated October 31, 2013 (for Model 737-600, -700, -700C, -800, -900, and -900ER series airplanes). As of the effective date of this AD, use Boeing Alert Service Bulletin 737-31A1332, Revision 4, dated October 31, 2013 (for Model 737-600, -700, -700C, -800, -900, and -900ER series airplanes), for the actions specified in paragraph (h) of this AD.
For airplanes having variable numbers YA001 through YA008 inclusive, YA251, YA501 through YA508 inclusive, and YC321 through YC325 inclusive: Before or concurrently with accomplishment of the actions specified in paragraph (g) of this AD, or within 18 months after the effective date of this AD, whichever occurs later, modify the instrument panels, install light assemblies, modify the wire bundles, and install a new circuit breaker, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 737-31A1332, Revision 4, dated October 31, 2013.
