AD 89-21-05

89-21-05 BOEING: Amendment 39-6329. Docket No. 89-NM-172-AD.

Applicability: Model 747-400 series airplanes, with Integrated Display System (IDS) software installed as identified in Boeing Telegraphic Maintenance Tip (M-7201-89-1141), dated July 27, 1989, certificated in any category.

Compliance: Required within 10 days after the effective date of this AD, unless previously accomplished.

To preclude the possibility of airplane status messages not being properly latched into memory which may prevent maintenance from properly dispatching the airplane, accomplish the following:

A. Change the FAA-approved maintenance program, with concurrence of the assigned FAA Principal Maintenance Inspector, to include the following special procedures, as described in Boeing Telegraphic Maintenance Tip 747-400 MT 31-12 (transmitted by Boeing message M-7201-89-1141, dated July 27, 1989):

1. If preparation of the airplane involved erasing any EICAS messages, as the final maintenance action prior to dispatch, simultaneously cycle power to the three electronic interface units (EIU).

2. Pull the following circuit breakers:

LOCATION NOMENCLATURE P7-1 F09 EIU L P7-1 F10 EIU C P7-2 F15 EIU R

3. After three seconds, restore all three circuit breakers to the power-on position.

B. Add the following to 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.

"Due to an IDS anomaly, information necessary for dispatch of subsequent flights may be lost if EICAS status messages are erased. To preclude this possibility, do not erase any EICAS status messages."

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, FAA, Northwest Mountain Region.

NOTE: The request should be forwarded through an FAA Principal Maintenance Inspector (PMI), who will either concur or comment, and then send it to the Manager, Seattle Aircraft Certification Office.

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.

All persons affected by this directive who have not already received the appropriate service information from the manufacturer may obtain copies upon request to Boeing Commercial Airplanes, P.O. Box 3707, Seattle, Washington 98124. This information may be examined at the FAA, Northwest Mountain Region, Transport Airplane Directorate, 17900 Pacific Highway South, Seattle, Washington, or Seattle Aircraft Certification Office, 9010 East Marginal Way South, Seattle, Washington.

This amendment (39-6329, AD 89-21-05) becomes effective on October 17, 1989.