Airworthiness Directive · Amendment 39-21383 · Air distribution system
The Boeing Company Airplanes
This AD applies to The Boeing Company Model 737-700 airplanes, certificated in any category, having line numbers (L/Ns) 481, 545, 684, 979, 1089, 1211, and 1223.
The FAA is adopting a new airworthiness directive (AD) for certain The Boeing Company Model 737-700 series airplanes. This AD requires repetitive testing to verify correct operation of the smoke clearance mode of the equipment cooling system and low pressure environmental control system, and corrective actions if necessary. This AD also requires installing new relays and changing the wiring to the environmental control system, among other actions. This AD was prompted by a determination that a repetitive test is needed to assess the components on airplanes equipped with a certain air distribution system configuration. The FAA is issuing this AD to address the unsafe condition on these products.
At the applicable times identified in paragraph 1.E., “Compliance” of Boeing Alert Service Bulletin 737-26A1137, Revision 2, dated January 27, 2020, except as required by paragraph (i) of this AD, do the test to verify correct operation of the smoke clearance mode of the equipment cooling system and low pressure environmental control system, and do all applicable corrective actions, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 737-26A1137, Revision 2, dated January 27, 2020. Do all applicable corrective actions before further flight. Repeat the test thereafter at intervals not to exceed 9,000 flight hours.
Before or concurrently with accomplishing the initial operational test required by paragraph (g) of this AD, install new relays and change the wiring to the environmental control system, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 737-26A1122, Revision 3, dated January 31, 2020. When the actions required by this paragraph are performed, the installation and changes specified in paragraph 1.B. “Concurrent Requirements” of Boeing Alert Service Bulletin 737-26A1122, Revision 3, dated January 31, 2020, must also be done.
Where Boeing Alert Service Bulletin 737-26A1137, Revision 2, dated January 27, 2020, uses the phrase “the R02 issue date of SB 737-26A1137,” this AD requires using “the effective date of this AD.”
As of the effective date of this AD, for the airplanes identified in paragraph (c) of this AD only, the requirements of AD 2016-04-06 are terminated.
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
