AD 2001-23-13 Airworthiness Directives; Boeing Model 747 Series Airplanes

Models named: 747 series, 747SP series. Read the applicability below — it usually turns on serial or part numbers too.

Model 747 series airplanes, line numbers 0001 through 1207, certificated in any category; excluding the airplanes having line number 1174 and Model 747SP series airplanes. 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 (c) 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.

Required as indicated, unless accomplished previously. To prevent damage to the flap system, adjacent systems, or structural components; or excessive skew of the trailing edge flap; which could result in flap asymmetry and consequent reduced controllability of the airplane, accomplish the following: Part Verification/Replacement/Modification (a) Within 18 months or 7,500 flight hours after December 31, 2001, whichever occurs later: Inspect the flap drive transmission of the trailing edge flaps at positions 2 and 7 to determine if a discrepant (“Belleville” spring design) torque brake is installed in the transmission, by verifying the transmission part number, per Boeing Service Bulletin 747-27-2374, dated November 18, 1999. Then do the actions specified in paragraphs (a)(1) and (a)(2) of this AD, as applicable. (1) If the part number of the flap drive transmission shows that no discrepant torque brake is installed, no further action is required by this AD. (2) If the part number of the flap drive transmission shows that a discrepant torque brake may be installed, within the compliance time required by paragraph (a) of this AD: Inspect the part number of the torque brake to verify whether it is a discrepant torque brake, per the Accomplishment Instructions of the service bulletin. (i) If the part number of the torque brake shows that it is not a discrepant torque brake, no further action is required by this AD. (ii) If the part number of the torque brake shows that it is a discrepant torque brake: Within the compliance time required by paragraph (a) of this AD either replace the transmission with a new, improved transmission or rework the existing transmission by replacing the torque brake with a new or reworked torque brake having the part number specified in the service bulletin; per the Accomplishment Instructions of the service bulletin. Spares (b) As of December 31, 2001, no person shall install on any airplane any transmission or torque brake assembly of the trailing edge flaps at positions 2 or 7, as identified in the “Existing Part Number” column of Paragraph 2.E. of Boeing Service Bulletin 747-27-2374, dated November 18, 1999. Alternative Methods of Compliance (c) 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. 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 2: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Seattle ACO. Special Flight Permit (d) 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 (e) The actions shall be done in accordance with Boeing Service Bulletin 747-27-2374, dated November 18, 1999. This incorporation by reference was approved previously by the Director of the Federal Register as of December 31, 2001 (66 FR 58918, November 26, 2001). 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. Effective Date (f) The effective date of this amendment remains December 31, 2001. Issued in Renton, Washington, on February 7, 2002. Ali Bahrami, Acting Manager, Transport Airplane Directorate, Aircraft Certification Service. [FR Doc. 02-3588 Filed 2-13-02; 8:45 am] BILLING CODE 4910-13-P