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ADs updated daily at www.Tdata.com
THE BOEING COMPANY:
Amendment 39-19512; Docket No. FAA-2018-0960; Product Identifier 2018-NM-151-AD.
TDATA NOTE: The original FAA copy had a typo in Figure 2 to paragraph (h). Tdata made the correction on the initial release so no change is necessary. (a) EFFECTIVE DATE This AD is effective December 21, 2018 to all persons except those persons to whom it was made immediately effective by Emergency AD 2018-23-51, issued on November 7, 2018, which contained the require- ments of this amendment. (b) AFFECTED ADS None. (c) APPLICABILITY This AD applies to all The Boeing Company Model 737-8 and -9 airplanes certificated in any category. (d) SUBJECT Air Transport Association (ATA) of America Code 27, Flight controls. (e) UNSAFE CONDITION This AD was prompted by analysis performed by the manufacturer showing that if an erroneously high single angle of attack (AOA) sensor input is received by the flight control system, there is a potential for repeated nose-down trim commands of the horizontal stabilizer. We are issuing this AD to address this potential resulting nose-down trim, which could cause the flight crew to have difficulty controlling the airplane, and lead to excessive nose-down attitude, significant altitude loss, and possible impact with terrain. (f) COMPLIANCE Comply with this AD within the compliance times specified, unless already done. (g) REVISION OF AIRPLANE FLIGHT MANUAL (AFM): CERTIFICATE LIMITATIONS Within 3 days after the effective date of this AD, revise the Certificate Limitations chapter of the applicable AFM to include the information in figure 1 to paragraph (g) of this AD. FIGURE 1 TO PARAGRAPH (G) OF THIS AD – CERTIFICATE LIMITATIONS ______________________________________________________________________ REQUIRED BY AD 2018-23-51 RUNAWAY STABILIZER ______________________________________________________________________ In the event of an uncommanded horizontal stabilizer trim movement, combined with any of the following potential effects or indications resulting from an erroneous Angle of Attack (AOA) input, the flight crew must comply with the Runaway Stabilizer procedure in the Operating Procedures chapter of this manual: - Continuous or intermittent stick shaker on the affected side only. - Minimum speed bar (red and black) on the affected side only. - Increasing nose down control forces. - IAS DISAGREE alert. - ALT DISAGREE alert. - AOA DISAGREE alert (if the option is installed). - FEEL DIFF PRESS light. - Autopilot may disengage. - Inability to engage autopilot. ______________________________________________________________________ (h) AFM REVISION: OPERATING PROCEDURES Within 3 days after the effective date of this AD,revise the Operating Procedures chapter of the applicable AFM to include the information in figure 2 to paragraph (h) of this AD. FIGURE 2 TO PARAGRAPH (H) OF THIS AD – OPERATING PROCEDURES ______________________________________________________________________ REQUIRED BY AD 2018-23-51 RUNAWAY STABILIZER ______________________________________________________________________ Disengage autopilot and control airplane pitch attitude with control column and main electric trim as required. If relaxing the column causes the trim to move, set stabilizer trim switches to CUTOUT. If runaway continues, hold the stabilizer trim wheel against rotation and trim the airplane manually. Note: The 737-8/-9 uses a Flight Control Computer command of pitch trim to improve longitudinal handling characteristics. In the event of erroneous Angle of Attack (AOA) input, the pitch trim system can trim the stabilizer nose down in increments lasting up to 10 seconds. In the event an uncommanded nose down stabilizer trim is experienced on the 737-8/-9, in conjunction with one or more of the indications or effects listed below, do the existing AFM Runaway Stabilizer procedure above, ensuring that the STAB TRIM CUTOUT switches are set to CUTOUT and stay in the CUTOUT position for the remainder of the flight. An erroneous AOA input can cause some or all of the following indica- tions and effects: - Continuous or intermittent stick shaker on the affected side only. - Minimum speed bar (red and black) on the affected side only. - Increasing nose down control forces. - IAS DISAGREE alert. - ALT DISAGREE alert. - AOA DISAGREE alert (if the option is installed). - FEEL DIFF PRESS light. - Autopilot may disengage. - Inability to engage autopilot. Initially, higher control forces may be needed to overcome any stabi- lizer nose down trim already applied. Electric stabilizer trim can be used to neutralize control column pitch forces before moving the STAB TRIM CUTOUT switches to CUTOUT. Manual stabilizer trim can be used before and after the STAB TRIM CUTOUT switches are moved to CUTOUT. ______________________________________________________________________ (i) ALTERNATIVE METHODS OF COMPLIANCE (AMOCS) (1) The Manager, Seattle ACO Branch, FAA, has the authority to approve AMOCs for this AD, if requested using the procedures found in 14 CFR 39.19. In accordance with 14 CFR 39.19, send your request to your principal inspector or local Flight Standards District Office, as appropriate. If sending information directly to the manager of the certification office, send it to the attention of the person identified in paragraph (j) of this AD. Information may be emailed to: 9-ANM-Seattle-ACOAMOC-Requests@faa.gov. (2) Before using any approved AMOC, notify your appropriate principal in- spector, or lacking a principal inspector, the manager of the local flight standards district office/certificate holding district office. (j) RELATED INFORMATION For further information about this AD, contact Douglas Tsuji, Senior Aerospace Engineer, Systems and Equipment Section, FAA, Seattle ACO Branch, 2200 South 216th St, Des Moines, WA 98198; phone and fax: 206- 231-3548; email: Douglas.Tsuji@faa.gov. (k) MATERIAL INCORPORATED BY REFERENCE None. Issued in Des Moines, Washington, on November 21, 2018. Michael Kaszycki, Acting Director, System Oversight Division, Aircraft Certification Service FOR FURTHER INFORMATION CONTACT: Douglas Tsuji, Senior Aerospace Engineer, Systems and Equipment Section, FAA, Seattle ACO Branch, 2200 South 216th St., Des Moines, WA 98198; phone and fax: 206-231-3548; email: Douglas. Tsuji@faa.gov.
DEPARTMENT OF TRANSPORTATION
Authority for This Rulemaking