91-05-16 BOEING: Amendment 39-6913. Docket No. 90-NM-154-AD.\n\n\tApplicability: Model 737 series airplanes, listed in Boeing Alert Service Bulletin 737- 32A1224, Revision 1, dated April 12, 1990, certificated in any category. \n\n\tCompliance: Required as indicated, unless previously accomplished. \n\n\tTo ensure the structural integrity of the main landing gear (MLG) actuator beam arm and actuator beam attached bolts, accomplish the following: \n\n\tA.\tPrior to the accumulation of 10,000 landings or 4 years of service, after new or overhauled main landing gear installation, whichever occurs first, or within the next 600 landings after the effective date of this AD, whichever occurs later, accomplish the following: \n\n\t\t1.\tPerform visual and ultrasonic inspections of the actuator beam arm clevis for evidence of cracking, in accordance with Boeing Alert Service Bulletin 737-32A1224, Revision 1, dated April 12, 1990. \n\n\t\t\ta.\tIf cracks are found, prior to further flight, remove andrework, or replace the actuator beam arm in accordance with the service bulletin. \n\n\t\t\tb.\tIf no cracks are found, repeat the ultrasonic inspections in accordance with the service bulletin, at intervals not to exceed 600 landings. \n\n\t\t2.\tRemove both of the actuator beam bolts and perform a one-time visual and dye penetrant inspection for evidence of plating degradation, corrosion, or cracking, in accordance with the service bulletin. If evidence of plating degradation, corrosion, or cracking is found, prior to further flight, rework or replace the bolts in accordance with the service bulletin. \n\n\tB.\tModification of the actuator beam arm, in accordance with Boeing Alert Service Bulletin 737-32A1224, Revision 1, dated April 12, 1990, constitutes terminating action for the inspections required by paragraph A.1. of this AD. \n\n\tC.\tAn alternate means of compliance or adjustment of the compliance time, which provides an acceptable level of safety, may be used when approved by the Manager, Seattle Aircraft Certification Office (ACO), FAA, Transport Airplane Directorate.\n\n\tNOTE: The request should be submitted directly to the Manager, Seattle ACO, and a copy sent to the cognizant FAA Principal Inspector (PI). The PI will then forward comments or concurrence to the Seattle ACO. \n\n\tD.\tSpecial flight permits may be issued in accordance with FAR 21.197 and 21.199 to comply with the requirements of this AD. \n\n\tAll persons affected by this directive who have not already received the appropriate service documents from the manufacturer may obtain copies upon request to Boeing Commercial Airplane Group, P.O. Box 3707, Seattle, Washington 98124. These documents may be examined at the FAA, Northwest Mountain Region, Transport Airplane Directorate, 1601 Lind Avenue SW., Renton, Washington. \n\n\tThis amendment (39-6913, AD 91-05-16) becomes effective on April 1, 1991.