86-18-04 BOEING: Amendment 39-5385. Applies to Model 737 series airplanes, line numbers 930 and above, listed in Boeing Service Letter 737-SL-27-38, dated January 16, 1986, certificated in any category. To detect nuts installed at the Body Buttock Line (BBL) 70.85 wing-to-body splice plate, the thrust reverser secondary deactivation pin, and the vertical fin front spar to closure rib attachments, that have insufficient self-locking torque characteristics, accomplish the following, unless already accomplished: \n\n\tA.\tWithin the next 18 months after the effective date of this AD, check the self- locking nuts, P/N BACN10JC12CM and P/N BACN10JC12CD, for proper self-locking torque in accordance with Paragraph II of Boeing Service Letter 737-SL-27-38, dated January 16, 1986, or later FAA-approved revision. If any self-locking nut does not meet the torque criteria specified in the service letter, replace it prior to further flight with an appropriate nut which meets the torque criteria. \n\n\tB.\tAn alternate means of the 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, FAA, Northwest Mountain Region. \n\n\tC.\tSpecial flight permits may be issued in accordance with FAR 21.197 and 21.199 to operate airplanes to a base for the accomplishment of inspections and/or modifications required by this AD. \n\n\tAll persons affected by this directive who have not already received the appropriate service document from the manufacturer may obtain copies upon request to the Boeing Commercial Airplane Company, P.O. Box 3707, Seattle, Washington 98124. This document may be examined at the FAA, Northwest Mountain Region, 17900 Pacific Highway South, Seattle, Washington, or the Seattle Aircraft Certification Office, 9010 East Marginal Way South, Seattle, Washington. \n\n\tThis amendment becomes effective September 11, 1986.