Airworthiness Directive · Amendment 39-19817 · Air conditioning
The Boeing Company Airplanes
This AD applies to all The Boeing Company Model 737-800, -900, and -900ER series airplanes, certificated in any category.
The FAA is superseding Airworthiness Directive (AD) 2017-12- 07, which applied to certain The Boeing Company Model 737-800, -900, and -900ER series airplanes. AD 2017-12-07 required replacing the affected left temperature control valve and control cabin trim air modulating valve. This AD retains the requirements of AD 2017-12-07, expands the applicability to include additional airplanes, and adds a new requirement for certain airplanes to identify and replace the affected parts. This AD was prompted by reports of in-flight failure of the left temperature control valve and control cabin trim air modulating valve. The FAA is issuing this AD to address the unsafe condition on these products.
This paragraph restates the requirements of paragraph (g) of AD 2017-12-07 with revised compliance language. For airplanes identified in Boeing Alert Service Bulletin 737-21A1203, dated June 8, 2016: Within 60 months after July 20, 2017 (the effective date of AD 2017-12-07), replace the left temperature control valve and control cabin trim air modulating valve, as applicable, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 737-21A1203, dated June 8, 2016.
For airplanes not identified in paragraph (g) of this AD with an original certificate of airworthiness or an original export certificate of airworthiness dated on or before the effective date of this AD, do the actions specified in paragraphs (h)(1) and (2) of this AD.
(1) Within 60 months after the effective date of this AD, perform a general visual inspection of the left temperature control valve and control cabin trim air modulating valve to determine the valve part numbers. A review of airplane maintenance records is acceptable in lieu of this inspection if the part numbers of the valves can be conclusively determined from that review.
(2) If the left temperature control valve or control cabin trim air modulating valve has part number 398908-4: Within 60 months after the effective date of this AD, replace the left temperature control valve or control cabin trim air modulating valve in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 737-21A1203, dated June 8, 2016.
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
