AD 97-05-10 Airworthiness Directives; Boeing Model 737 Series Airplanes

Models named: 737 series. Read the applicability below — it usually turns on serial or part numbers too.

Model 737 series airplanes, having a main rudder power control unit (PCU) that is identified in Boeing Service Letter 737-SL-27-112-B, dated February 6, 1997; certificated in any category. Note 1: This AD applies to each airplane identified in the preceding applicability provision, regardless of whether it has been otherwise 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) 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 cracking and seizing of the internal summing lever assembly bearing of the main rudder power control unit (PCU), which could result in uncommanded rudder movement, accomplish the following: (a) Within 90 days after the effective date of this AD, remove the main rudder PCU and replace it with a serviceable unit in accordance with Boeing Service Letter 737-SL-27-112-B, dated February 6, 1997. (b) As of 90 days after the effective date of this AD, no person shall install on any airplane a main rudder PCU having a serial number specified in Boeing Service Letter 737-SL-27-112-B, dated February 6, 1997, unless the following actions have been accomplished in accordance with Boeing Service Letter 737-SL-27-112- B, dated February 6, 1997. (1) Remove the internal summing lever assembly of the main rudder PCU in accordance with the service letter. (2) Perform a one-time visual inspection using 10-power magnification and strong light to detect cracking of the bearing, in accordance with the service letter. (i) If no cracking is detected during the visual inspection, perform an eddy current inspection to detect cracking of the bearing in accordance with the service letter. (A) If no cracking is detected during the eddy current inspection, the unit may be reinstalled on the airplane after it is reassembled and tested in accordance with the service letter. (B) If any cracking is detected during the eddy current inspection, before reinstallation of the PCU on any airplane, repair the lever assembly, reassemble, and test; in accordance with the service letter. (ii) If any cracking is detected during the visual inspection, before reinstallation of the PCU on any airplane, repair the lever assembly, reassemble, and test, in accordance with the service letter. (c) Within 14 days after accomplishing the requirements of paragraph (b) of this AD, submit a report of any cracked PCU bearing to the Manager, Seattle Aircraft Certification Office (ACO), FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, WA 98055-4056; fax (206) 227-1181. The report shall include the information specified in paragraphs (c)(1) and (c)(2) of this AD. Information collection requirements contained in this regulation have been approved by the Office of Management and Budget (OMB) under the provisions of the Paperwork Reduction Act of 1980 (44 U.S.C. 3501 et seq.) and have been assigned OMB Control Number 2120- 0056. (1) The PCU part number and serial number. (2) The date of the inspection and the inspection findings. (d) 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 ACO. 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. (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. (f) The actions shall be done in accordance with Boeing Service Letter 737-SL-27-112-B, dated February 6, 1997. 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. (g) This amendment becomes effective on March 19, 1997. Issued in Renton, Washington, on February 25, 1997. James V. Devany, Acting Manager, Transport Airplane Directorate, Aircraft Certification Service. [FR Doc. 97-5159 Filed 2-28-97; 12:40 pm] BILLING CODE 4910-13-P