Superseded. This AD was superseded by AD 2020-01-11. Verify which one applies to your serial and effectivity before any maintenance action.
AD 2017-12-07
Effective 07/20/2017 · Published 06/15/2017
Airworthiness Directives; The Boeing Company Airplanes
Summary
We are adopting a new airworthiness directive (AD) for certain The Boeing Company Model 737-800, -900, and -900ER series airplanes. This AD was prompted by reports of in-flight failure of the left temperature control valve and control cabin trim air modulating valve. This AD requires replacing the left temperature control valve and control cabin trim air modulating valve. We are issuing this AD to address the unsafe…