AD 99-08-02 R1

99-08-02 R1 BOEING: Amendment 39-11215. Docket 99-NM-112-AD. Revises AD 99-08-02, Amendment 39-11106.

Applicability: Model 747 series airplanes having line numbers 1 through 1124 inclusive, certificated in any category.

NOTE 1: This AD applies to each airplane identified in the preceding applicability provision, regardless of whether it has been modified, altered, or repaired in the area subject to the requirements of this AD. For airplanes that have been modified, altered, or repaired so that the performance of the requirements of this AD is affected, the owner/operator must request approval for an alternative method of compliance in accordance with paragraph (d)(1) of this AD. The request should include an assessment of the effect of the modification, alteration, or repair on the unsafe condition addressed by this AD; and, if the unsafe condition has not been eliminated, the request should include specific proposed actions to address it.

Compliance: Required asindicated, unless accomplished previously.

To prevent ignition sources and consequent fire/explosion in the center fuel tank, accomplish the following:

Fuel Tank Inspection and Bonding Test

(a) For those airplanes listed in Boeing Service Bulletin 747-28-2205, Revision 1, dated April 16, 1998: Within 24 months after the effective date of this AD, accomplish paragraphs (a)(1) and (a)(2) of this AD, in accordance with the service bulletin.

(1) Perform a one-time visual inspection of the center fuel tank wiring and components to detect discrepancies (damage, disbonding, and incorrect installation). For the purposes of this AD, a visual inspection is considered to be a general visual inspection, which is defined as: "A visual examination of an interior or exterior area, installation or assembly to detect obvious damage, failure or irregularity. This level of inspection is made under normally available lighting conditions such as daylight, hangar lighting, flashlight, ordrop-light and may require removal or opening of access panels or doors. Stands, ladders, or platforms, may be required to gain proximity to the area being checked." If any discrepancy is detected, prior to further flight, repair the discrepant component, or replace it with a new or serviceable component. And

(2) Perform a one-time electrical bonding test of the center fuel tank components. If any measured resistance exceeds the limits specified by the service bulletin, prior to further flight, rework the discrepant component.

NOTE 2: Actions performed in accordance with Boeing Service Bulletin 747-28-2205, dated June 27, 1997, accomplished prior to the effective date of this AD, are considered acceptable for compliance only with the corresponding applicable actions specified in this AD. This excludes certain actions that are not described in that bulletin, such as inspection and testing of the body fuel tank components that are described in Revision 1 of Boeing ServiceBulletin 747-28-2205. Regardless of which version of the service bulletin is used to detect any discrepancies, the repair and replacement requirements of this AD apply.

NOTE 3: Airplanes required to accomplish paragraph (b) of this AD are exempt from accomplishing steps 1 through 9 in Figure 11 of Boeing Service Bulletin 747-28-2205, Revision 1, dated April 16, 1998.

FQIS Testing and Probe Replacement

(b) For those airplanes listed in Boeing Alert Service Bulletin 747-28A2208, dated May 14, 1998: Within 24 months after the effective date of this AD, perform a one-time insulation resistance test of the fuel quantity indication system (FQIS), a one-time visual inspection of the FQIS wiring and components to detect discrepancies (chafing damage to the wiring and incorrect configuration of the terminal blocks), replacement of FQIS probes (tank units and compensators) with new or serviceable components in accordance with Figure 5 of the alert service bulletin, and system adjustment and system operational test; in accordance with the alert service bulletin. For the purposes of this AD, a visual inspection is considered to be a general visual inspection, which is defined as: "A visual examination of an interior or exterior area, installation or assembly to detect obvious damage, failure or irregularity. This level of inspection is made under normally available lighting conditions such as daylight, hangar lighting, flashlight, or drop-light and may require removal or opening of access panels or doors. Stands, ladders, or platforms, may be required to gain proximity to the area being checked." If any discrepancy is detected, prior to further flight, perform corrective actions in accordance with the alert service bulletin.

NOTE 4: For airplanes on which steps 1 through 9 in Figure 11 of Boeing Service Bulletin 747-28-2205, dated June 27, 1997, or Revision 1, dated April 16, 1998, were accomplished prior to the effective date of this AD, steps 1 through 6 in Figure 16 of Boeing Alert Service Bulletin 747-28A2208, dated May 14, 1998, are not required.

Flame Arrestor Installation

(c) For airplanes having line numbers 1 through 971 inclusive: Within 24 months after the effective date of this AD, install a flame arrestor in the inlet line of the electrical motor-operated scavenge pump of the center fuel tank, in accordance with Boeing Alert Service Bulletin 747-28A2210, dated May 14, 1998.

Alternative Methods of Compliance

(d) (1) An alternative method of compliance or adjustment of the compliance time that provides an acceptable level of safety may be used if approved by the Manager, Seattle Aircraft Certification Office, FAA, Transport Airplane Directorate. Operators shall submit their requests through an appropriate FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, Seattle ACO.

(2) Alternative methods of compliance, approved previously in accordance with AD 99-08-02, amendment 39-11106, are approved as alternative methods of compliance with paragraph (a) of this AD.

NOTE 5: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Seattle ACO.

Special Flight Permits

(e) Special flight permits may be issued in accordance with sections 21.197 and 21.199 of the Federal Aviation Regulations (14 CFR 21.197 and 21.199) to operate the airplane to a location where the requirements of this AD can be accomplished.

Incorporation by Reference

(f) The actions shall be done in accordance with Boeing Service Bulletin 747-28-2205, Revision 1, dated April 16, 1998; Boeing Alert Service Bulletin 747-28A2208, dated May 14, 1998; and Boeing Alert Service Bulletin 747-28A2210, dated May 14, 1998. This incorporation by reference was approved previously by the Director of the Federal Register as of May 11, 1999 (64 FR 16625, April 6, 1999). Copies may be obtained from Boeing Commercial Airplane Group, P.O. Box 3707, Seattle, Washington 98124-2207. Copies may be inspected at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at the Office of the Federal Register, 800 North Capitol Street, NW, suite 700, Washington, DC.

(g) The effective date of this amendment remains May 11, 1999.