AD 77-18-06

77-18-06 BOEING: Amendment 39-3034 as amended by Amendment 39-3048. Applies to Boeing Model 727 series airplanes with horizontal stabilizer center section front spar junction fittings, P/Ns 65- 17448-1 or 65-31273-1, certificated in all categories. Compliance required as indicated.

To detect cracks in the horizontal stabilizer center section front spar fitting, accomplish the following: A. Within the next 750 flight hours time-in-service from the effective date of this AD or prior to January 1, 1978, whichever occurs first, unless accomplished per paragraph B of AD 77-10-08 or since April 20, 1977, inspect the horizontal stabilizer center section front spar junction fittings for cracks in the forward lugs in accordance with one of the inspections of paragraph B of this AD or dye penetrant procedures with the jackscrew support arms removed. Following the inspection, apply LPS 3, BMS 3-23 or equivalent corrosion inhibitor to the lugs. Reinspect per paragraph C of this AD.B. Inspect the eight (8) lugs of the horizontal stabilizer center section front spar junction fitting which attach the jackscrew support arms to the fitting in accordance with one of the following: 1. Eddy current inspection with the jackscrew support arms removed as specified in Boeing Alert Service Bulletin No. 727-55-A69, or later FAA approved revisions, or equivalent. 2. Low frequency eddy current inspection with the jackscrew support arms installed as specified in Boeing Alert Service Bulletin No. 727-55-A69, Revision 1, or later FAA approved revisions. 3. A procedure approved by the Chief, Engineering and Manufacturing Branch, FAA Northwest Region. Following each inspection, apply LPS 3, BMS 3-23 or equivalent corrosion inhibitor to the lugs. C. 1. Except as provided for in paragraph C.2 below, repeat the inspections per paragraph B of this AD at intervals of either a or b below: a. 1,500 flight hours time-in-service or nine (9) months from the last inspection, whichever occurs first, or b. 3,000 flight hours time-in-service or eighteen (18) months from the last inspection, whichever occurs first, if the fittings are reworked in accordance with Boeing Alert Service Bulletin No. 727-55-A69, Revision 1, or later FAA approved revisions, or in a manner approved by the Chief, Engineering and Manufacturing Branch, FAA Northwest Region. 2. Airplanes which were inspected prior to the effective date of this AD (September 12, 1977), and since April 20, 1977 (by eddy current or dye penetrant methods equivalent to those specified in paragraph B of AD 77-10-08), may be reinspected in accordance with a or b below but are subject to the limitations set out in c below: a. Within 1,500 flight hours time-in-service from the last inspection. b. Within 750 flight hours time-in-service from the effective date of this AD (September 12, 1977). c. Notwithstanding the provisions of paragraph a and b above, the repeat inspection must beaccomplished no later than nine (9) months from the effective date of this AD and thereafter at the intervals specified in C.1. D. Cracked fittings are to be replaced or repaired prior to further flight in accordance with Boeing Alert Service Bulletin No. 727-55-A69, or later FAA approved revisions, or in a manner approved by the Chief, Engineering and Manufacturing Branch, FAA Northwest Region. Report findings of cracks directly to the Chief, Engineering and Manufacturing Branch, FAA Northwest Region, within 64 hours after detection. Include in the report, description of the crack(s), method used to detect the crack(s), and airplane total time in flight hours. (Reporting approved by the Bureau of the Budget under BOB No. 04- R0174.) E. Terminating action of this AD consists of replacement of the horizontal stabilizer center section front spar junction fitting with a 7075-T73 aluminum alloy material fitting, Boeing P/N 65-31273- 4, or equivalent approved by the Chief, Engineering and Manufacturing Branch, FAA Northwest Region. F. Airplanes may be ferried to a maintenance base for repairs or replacement in accordance with FAR 21.197, subject to prior approval by the Chief, Engineering and Manufacturing Branch, FAA Northwest Region. G. Requests for adjustments of the inspection threshold and intervals in this AD should be made directly to the Chief, Engineering and Manufacturing Branch, FAA Northwest Region. Such requests should contain substantiating data to justify the increase. The manufacturer's specifications and procedures identified and described in this directive are incorporated herein and made a part hereof pursuant to 5 U.S.C. 552(a)(1). All persons affected by this directive who have not already received these documents from the manufacturer, may obtain copies upon request to Boeing Commercial Airplane Company, P. O. Box 3707, Seattle, Washington 98124. The documents may also be examined at FAA Northwest Region, 9010 East Marginal Way South, Seattle, Washington 98108.

Airworthiness Directive 77-10-08, Amendment 39-2901, was superseded by Amendment 39-3034. Amendment 39-3034 became effective September 12, 1977. This amendment 39-3048 becomes effective October 3, 1977.