FUEL TANK EXPLOSION

Boeing: Category - Airframe

Effective Date - 06/28/1999

Recurring - Yes Supersedes - T99-12-51

Superseded by - N/A

Amendment 39-11199. Docket 99-NM-121-AD. Supersedes Telegraphic AD T99-12-51.

Applicability: All Model 727 series airplanes, 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 (l) 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 as indicated, unless accomplished previously. To prevent fuel tank explosion resulting from arc-through of the fuel boost pump wiring conduits, accomplish the following:

(a) For airplanes with 50,000 or more total flight hours as of the date of receipt of AD T99-12-51, within 5 days after the  effective date of this AD, accomplish the requirements of paragraph (c) of this AD.

(b) For airplanes with less than 50,000 total flight hours as of the date of receipt of AD T99-12-51, prior to the accumulation of 30,000 total flight hours, or within 10 days after receipt of this AD, whichever occurs later, accomplish the requirements of paragraph(c) of this AD.

Initial Inspection and Corrective Action
(c) Except as provided in paragraphs (d) and (e) of this AD, perform a boost pump dry bay inspection and applicable follow-on corrective actions, in accordance with steps 1 through 6 of the "Boost Pump Dry Bay Inspection," specified in Boeing All Operator Message M-7200-99-04035, dated May 21, 1999, or in accordance with Boeing Alert Service Bulletin 727-28A0126, dated May 24, 1999.

(d) For airplanes on which the actions specified in step 5-E-<3> of Boeing All Operator Message M-7200-99-04035, dated May 21, 1999, are accomplished, the fuel tank in which the conduit has been replaced must be refueled prior to accomplishing step 6.

(e) Accomplishment of the requirements of paragraph (c) of this AD is not required if the requirements of paragraph (i) of this AD are accomplished within the times specified in paragraph (a) or (b) of this AD, as applicable.

New Requirements of This AD
(f) For airplanes with 50,000 or more total flight hours as of the effective date of this AD, within 20 days after the effective  date of this AD, accomplish the requirements of paragraph (i) of this AD.

(g) For airplanes with less than 50,000 total flight hours, but more than 30,000 total flight hours, as of the effective date of  this AD, within 30 days after the effective date of this AD, accomplish the requirements of paragraph (i) of this AD.

(h) For airplanes with 30,000 total flight hours or fewer, as of the effective date of this AD, within 90 days after the effective date of this AD, accomplish the requirements of paragraph (i) of this AD. Detailed Visual Inspection, Corrective Action, and Installation
(i) Perform a detailed visual inspection of the in-tank fuel boost pump wire bundles, and applicable corrective actions; and,  except as provided in paragraph (j) of this AD, install sleeving over the wire bundles; in accordance with Boeing Alert Service Bulletin 727-28A0126, dated May 24, 1999.

Note 2: For the purposes of this AD, a detailed visual inspection is defined as an intensive visual examination of a specific structural area, system, installation, or assembly to detect damage, failure, or irregularity. Available lighting is normally supplemented with a direct source of good lighting at intensity deemed appropriate by the inspector. Inspection aids such as mirrors, magnifying lenses, etc. may be used. Surface cleaning and elaborate access procedures may be required.

Installation: Possible Deferral
(j) Installation of sleeving over the wire bundles, as required by paragraph (i) of this AD, may be deferred if, within 18 months or 6,000 flight hours, whichever occurs first, after accomplishment of the inspection and applicable corrective actions required by paragraph (i), the following actions are accomplished: Perform a detailed visual inspection of the in-tank fuel boost pump wire bundles, and applicable corrective actions; and install sleeving over the wire bundles; in accordance with Boeing Alert Service Bulletin 727-28A0126, dated May 24, 1999.

Repetitive Inspections and Corrective Actions
(k) Repeat the detailed visual inspection and applicable corrective actions required by paragraphs (i) and (j) of this AD at  intervals not to exceed 30,000 flight hours.

Alternative Methods of Compliance (l) 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 (ACO), 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.

Note 3: 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 (m) 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
(n) The actions shall be done in accordance with Boeing All Operator Message (AOM) M-7200-99-04035, dated May 21, 1999, or Boeing Alert Service Bulletin 727-28A0126, dated May 24, 1999, as applicable. 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 98124-2207. 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.

(o) This amendment becomes effective on June 28, 1999, to all persons except those persons to whom it was made immediately effective by telegraphic AD T99-12-52, issued on May 24, 1999, which contained the requirements of this amendment.

FOR FURTHER INFORMATION CONTACT: Jon Regimbal, Aerospace Engineer, Propulsion Branch, ANM-140S, FAA, Transport Airplane Directorate, Seattle Aircraft Certification Office, 1601 Lind Avenue, S.W., Renton, Washington 98055-4056; telephone (425) 227-2687; fax (425) 227-1181.