AD 91-03-04

91-03-04 BOEING: Amendment 39-6864. Docket No. 90-NM-281-AD.

Applicability: All Model 747-400 series airplanes, certificated in any category.

Compliance: Required within 30 days after the effective date of this AD, unless previously accomplished.

To prevent inadvertently reversing the direction of flight due to the flight management system commanding an unanticipated turn to intercept an out-of-sequence waypoint, accomplish the following:

A. Install placards on or directly adjacent to both the left and right Control Display Units (CDU), in positions clearly visible to the flight crew, stating: Use of "ABEAM PTS" FMC Function Prohibited.

B. Revise the Limitations Section, Electronics Subsection, of the FAA-approved Airplane Flight Manual (AFM), to add the following statement: "Do not use the FMC ABEAM PTS Function." This may be accomplished by inserting a copy of this AD in the AFM.

C. An alternate means 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 submitted directly to the Manager, Seattle ACO, and a copy sent to the cognizant FAA Principal Inspector (PI). The PI will then forward comments or concurrence to the Seattle ACO.

D. 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.

This amendment (39-6864, AD 91-03-04) becomes effective on February 4, 1991.