Airworthiness Directive · Amendment 39-17280 · Air conditioning
The Boeing Company Airplanes
Superseded. A later AD replaced this one: AD 2015-19-06. Comply with the one in force.
This AD applies to The Boeing Company Model 747-400 and -400F series airplanes, certificated in any category, as identified in Boeing Alert Service Bulletin 747-21A2523, Revision 1, dated October 3, 2011.
We are adopting a new airworthiness directive (AD) for certain The Boeing Company Model 747-400 and -400F series airplanes. This AD was prompted by multiple reports of integrated display unit (IDU) malfunctions and mode control panel (MCP) malfunctions. This AD requires installing new software, replacing the duct assembly with a new duct assembly, making wiring changes, and routing certain wire bundles. We are issuing this AD to prevent IDU malfunctions, which could affect the ability of the flightcrew to read primary displays for airplane attitude, altitude, or airspeed, and consequently reduce the ability of the flightcrew to maintain control of the airplane.
Within 12 months after the effective date of this AD: Install integrated display system software, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 747-21A2523, Revision 1, dated October 3, 2011.
Note 1 to paragraph (g) of this AD: Boeing Alert Service Bulletin 747-21A2523, Revision 1, dated October 3, 2011, refers to the service bulletins specified in paragraphs (g)(1), (g)(2), and (g)(3) of this AD as additional sources of guidance for the software installation specified by paragraph (g) of this AD, which are not incorporated by reference in this AD.
(1) Boeing Service Bulletin 747-31-2426, dated July 29, 2010 (for airplanes with Rolls-Royce engines).
(2) Boeing Service Bulletin 747-31-2427, dated July 29, 2010 (for airplanes with General Electric engines).
(3) Boeing Service Bulletin 747-31-2428, dated July 29, 2010 (for airplanes with Pratt & Whitney engines).
Within 60 months after the effective date of this AD: Replace the duct assembly with a new duct assembly, do wiring changes, and route certain wire bundles, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 747-21A2523, Revision 1, dated October 3, 2011.
