AD 92-08-06

92-08-06 BOEING: Amendment 39-8217. Docket No. 91-NM-194-AD. Supersedes AD 89-18-01, Amendment 39-6305.

Applicability: Model 737-200 series airplanes; equipped with Sperry SP177 autopilot Flight Control Computers and Mode Control Panels (MCP); certificated in any category.

Compliance: Required as indicated unless previously accomplished.

To prevent uncommanded changes to the target altitude displayed in the altitude window of the autopilot mode control panel (MCP), accomplish the following:

(a) Within 10 days after September 5, 1989 (the effective date of AD 89-18-01, Amendment 39-6305), incorporate the following procedures into the Limitations Section of the FAA-approved Airplane Flight Manual (AFM). This may be accomplished by inserting a copy of this AD in the AFM.

"Autopilot Limitations For airplanes with SP177 autopilot MCP. Flightcrews must use the following procedures:

1. Check MCP settings after any electrical power interruptions.

2. Following change in ALT selection in the MCP window, check ALT display to ensure desired altitude is displayed.

3. Closely monitor altitude during all altitude changes to ensure that the autopilot captures and levels off at the desired altitude.

NOTE: Standard 'callouts,' crew coordination, and cross-checking of MCP settings and flight instruments are necessary to detect any nonselected MCP display number changes."

(b) Within 6 months after the effective date of this AD, modify the MCP in accordance with Boeing Alert Service Bulletin 737-22A1096, dated April 12, 1990.

(c) After completion of paragraph (b) of this AD, remove the Airplane Flight Manual limitation required by paragraph (a) of this AD.

(d) An alternative method of compliance or adjustment of the compliance time, which provides an acceptable level of safety, may be used when approved by the Manager, Seattle Aircraft Certification Office (ACO), FAA, Transport Airplane Directorate.

NOTE: The request should be forwarded through an FAA Principal Maintenance Inspector, who may concur or comment and then send it to the Manager, Seattle ACO.

(e) Special flight permits may be issued in accordance with FAR 21.197 and 21.199 to operate airplanes to a base in order to comply with the requirements of this AD.

(f) The modification shall be done in accordance with Boeing Alert Service Bulletin 737-22A1096, dated April 12, 1990. This incorporation by reference was approved by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR Part 51. Copies may be obtained from Boeing Commercial Airplane Group, P.O. Box 3707, Seattle, Washington 98124. Copies may be inspected at the FAA, Transport Airplane Directorate, 1601 Lind Avenue SW., Renton, Washington; or at the Office of the Federal Register, 1100 L Street NW., Room 8401, Washington, DC.

(g) This amendment becomes effective on May 29, 1992.