AD 97-26-01 Airworthiness Directives; Boeing Model 737-100, -200, -300, -400, and -500 Series Airplanes

Models named: 737-100, -200, -300, -400, -500 series. Read the applicability below — it usually turns on serial or part numbers too.

Model 737-100, -200, -300, -400, and -500 series airplanes, having line numbers 1 through 2814 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 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 (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 uncommanded movement of the rudder or increased rudder pedal forces, and consequent reduced controllability of the airplane, accomplish the following: (a) Within 18 months or 4,500 hours time-in-service after the effective date of this AD, whichever occurs later; and thereafter at intervals not to exceed 18 months or 4,500 hours time-in-service, whichever occurs later: Perform an inspection to detect galling on the input shaft and bearing of the standby rudder PCU by accomplishing paragraphs (a)(1) through (a)(10) of this AD. (1) Shut off all hydraulic power. (2) Gain access to the standby rudder actuator. (3) Disconnect the input rod from the standby actuator. (4) Using a push/pull spring scale (minimum +/-10% accuracy at 1.0 pound; preferably one having a peak load memory function), push on the standby rudder actuator input lever with sufficient force to move the lever from the neutral position up to, but not touching, the aft stop. The scale must be contacting the input lever at approximately the clevis bolt centerline. While applying the load required to move the lever, the scale must be maintained at an angle perpendicular to the lever arm (not to exceed 20 degrees from perpendicular). The force required to move the input lever throughout this range of motion must not exceed one pound. (5) Repeat the test specified in paragraph (a)(4) of this AD, moving the lever arm from the aft stop position up to the forward stop, but not touching. The force required to move the input lever throughout this range of motion must not exceed one pound. (6) Repeat the test specified in paragraph (a)(4) of this AD, moving the lever arm from the forward stop position back to the neutral position. The force required to move the input lever throughout this range of motion must not exceed one pound. (7) If the actuator force encountered during any of the procedures required by paragraph (a)(4), (a)(5), or (a)(6) of this AD exceeds one pound, prior to further flight, replace the standby rudder actuator with a serviceable actuator, and test the standby rudder actuator in accordance with the procedure specified in paragraph (a)(9) of this AD. (8) If the actuator force encountered during any of the procedures required by paragraph (a)(4), (a)(5), or (a)(6) of this AD is one pound or less, prior to further flight, reconnect the input rod to the standby rudder actuator, and test the standby rudder actuator in accordance with the procedure specified in paragraph (a)(9) of this AD. (9) Perform a functional test of the standby rudder actuator in accordance with Maintenance Manual 737-100/-200, Chapter 27-21-141, removal/installation (for Model 737-100 and -200 series airplanes); or maintenance Manual 737-300/-400/-500, Chapter 27-21-24, removal/ installation (for Model 737-300, -400, and -500 series airplanes). (10) Restore the airplane to its normal condition. (b) Within 3 years after the effective date of this AD, replace the input bearing of the standby rudder PCU with an improved bearing in accordance with Dowty Aerospace Los Angeles Service Bulletin 1150-27-04, dated December 5, 1996; or in accordance with a method approved by the Manager, Seattle Aircraft Certification Office (ACO), FAA, Transport Airplane Directorate. Replacement of the input bearing with an improved bearing in accordance with the service bulletin constitutes terminating action for the requirements of this AD. (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 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 2: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Seattle, ACO. (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. [[Page 65600]] (e) Except as provided by paragraph (b) of this AD, the replacement shall be done in accordance with Dowty Aerospace Los Angeles Service Bulletin 1150-27-04, dated December 5, 1996. 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 Dowty Aerospace Los Angeles, 1700 Business Center Drive, Duarte, California 91010-2859. 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. (f) This amendment becomes effective on January 20, 1998. Issued in Renton, Washington, on December 8, 1997. Stewart R. Miller, Acting Manager, Transport Airplane Directorate, Aircraft Certification Service. [FR Doc. 97-32590 Filed 12-12-97; 8:45 am] BILLING CODE 4910-13-U