AD 2011-03-14 Airworthiness Directives; The Boeing Company Model 737-100, -200, -200C, -300, -400, and -500 Series Airplanes

Models named: 737-100, -200, -200C, -300, -400, -500 series, 737-400 series. Read the applicability below — it usually turns on serial or part numbers too.

This AD applies to the airplanes, certificated in any category, identified in paragraphs (c)(1) and (c)(2) of this AD. (1) The Boeing Company Model 737-100, -200, -200C, -300, -400, and -500 series airplanes, as identified in Boeing Alert Service Bulletin 737-31A1325, dated January 11, 2010. (2) The Boeing Company Model 737-400 series airplanes identified in Boeing Alert Service Bulletin 737-31A1398, dated January 7, 2010.

You are responsible for having the actions required by this AD performed within the compliance times specified, unless the actions have already been done. Installation of Warning Indicator Lights (g) For airplanes identified in Boeing Alert Service Bulletin 737-31A1325, dated January 11, 2010: Within 36 months after the effective date of this AD, install two warning level indicator lights on the P2-2 center instrument panel in the flight compartment, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 737-31A1325, dated January 11, 2010. Activation of Warning Indicator Lights (h) For airplanes identified in Boeing Alert Service Bulletin 737-31A1398, dated January 7, 2010: Within 36 months after the effective date of this AD, activate the cabin altitude warning and takeoff configuration warning lights, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 737-31A1398, dated January 7, 2010. Airplane Flight Manual (AFM) Revisions (i) Before further flight after doing the installation or activation of the warning lights required by paragraph (g) or (h) of this AD, do the actions specified in paragraphs (i)(1), (i)(2), and (i)(3) of this AD. (1) Revise the Limitations Section of the applicable Boeing 737 AFM by doing the actions specified in paragraphs (i)(1)(i) and (i)(1)(ii) of this AD. (i) Delete the “CABIN ALTITUDE WARNING TAKEOFF BRIEFING” added by AD 2008-23-07. (ii) Add the following statement. This may be done by inserting a copy of this AD into the applicable AFM. “For airplanes approved for maximum takeoff and landing altitudes above 8,400 feet pressure altitude, change the limitation for Maximum Takeoff and Landing pressure altitude as follows: With the CABIN ALTITUDE and TAKEOFF CONFIG lights installed and operative on those airplanes without the High Altitude Landing switch installed, maximum takeoff and landing altitude is limited to 9,000 feet pressure altitude.” (2) Revise the Emergency Procedures Section of the applicable Boeing 737 AFM by doing the actions specified in paragraphs (i)(2)(i), (i)(2)(ii), (i)(2)(iii), and (i)(2)(iv) of this AD. (i) Delete the procedure “WARNING HORN—CABIN ALTITUDE OR CONFIGURATION” added by AD 2006-13-13. If the title of this procedure has been changed according to FAA Alternative Method of Compliance AMOC Letter 130S-09-134a, dated April 28, 2009, delete the procedure approved according to that AMOC letter. (ii) Delete the procedure entitled “CABIN ALTITUDE WARNING OR RAPID DEPRESSURIZATION” added by AD 2003-03-15 R1 and modified by paragraph (g) of AD 2006-13-13. (iii) If the procedure entitled “CABIN ALTITUDE (Airplanes with the CABIN ALTITUDE lights installed)” is currently contained in the applicable Boeing 737 AFM, delete the procedure entitled “CABIN ALTITUDE (Airplanes with the CABIN ALTITUDE lights installed).” (iv) Add the following statement. This may be done by inserting a copy of this AD into the applicable AFM. “CABIN ALTITUDE WARNING OR RAPID DEPRESSURIZATION (required by AD 2011-03-14) Condition: The CABIN ALTITUDE warning light illuminates or the intermittent warning horn sounds in flight above 10,000 ft MSL. RECALL Oxygen Masks and Regulators ON, 100% Crew Communications ESTABLISH REFERENCE Pressurization Mode Selector MANUAL Outflow Valve Switch CLOSE If Cabin Altitude is uncontrollable: Emergency Descent (If Required) INITIATE Passenger Oxygen Switch ON” (v) The following steps may be added to the AFM procedure specified by paragraph (i)(2)(iv) of this AD. These steps should be added following “Passenger Oxygen Switch * * * On.” “Thrust Levers CLOSE Speed Brakes FLIGHT DETENT Target Speed VMO/MMO” (3) Revise the Normal Procedures Section of the applicable Boeing 737 AFM by doing the actions specified in paragraphs (i)(3)(i) and (i)(3)(ii) of this AD. (i) Delete the “CABIN ALTITUDE WARNING TAKEOFF BRIEFING” procedure added by AD 2008-23-07. (ii) Add the following statement. This may be done by inserting a copy of this AD into the applicable AFM. “For normal operations, the pressurization mode selector should be in AUTO prior to takeoff. (Required by AD 2011-03-14)” Note 1: When statements identical to those specified in paragraphs (i)(1)(ii), (i)(2)(iv), and (i)(3)(ii) of this AD have been included in the general revisions of the AFM, the general revisions may be inserted into the AFM, and the copies of this AD may be removed from the AFM. Terminating Action for

This AD results from a design change in the cabin altitude warning system that would address the identified unsafe condition. The Federal Aviation Administration is issuing this AD to prevent failure of the flightcrew to recognize and react properly to a valid cabin altitude warning horn, which could result in incapacitation of the flightcrew due to hypoxia (lack of oxygen in body) and consequent loss of control of the airplane.