93-04-03 GENERAL DYNAMICS: Amendment 39-8505. Docket 92-NM-202-AD.
Applicability: Model 340, 440, and C-131B through C-131H (military) series airplanes, all serial numbers, certificated in any category, including those modified for turbo-propeller power.
Compliance: Required as indicated, unless accomplished previously.
To prevent failure of the stabilizer attach fittings, and potential subsequent loss of a horizontal or vertical stabilizer, accomplish the following:
(a) Within 12 months or 1,500 flight hours after the effective date of this AD, whichever occurs first, accomplish paragraphs (a)(1) and (a)(2) of this AD:
(1) Inspect both horizontal stabilizers and vertical stabilizer attach fittings in accordance with General Dynamics, Convair Division, Service Bulletin 640(340D) S.B. No. 55-6, Paragraph 2.A, Accomplishment Instructions, Part 1, dated September 1, 1992. If the attach fittings are not within the tolerance limitations specified in the Convair 440 Structural Repair Manual, prior to further flight, bush the fittings in accordance with the repair manual.
(2) Perform a hardness test of the horizontal and vertical stabilizer taper pins and split sleeve bushings in accordance with normal maintenance procedures. The equivalent strength values for the pins and bushings based on the hardness test must be between 160-180 ksi. Taper pins and split sleeve bushing received directly from Convair and bearing the Convair mark are excluded from this requirement.
NOTE: The Convair mark is an etched mark:
CV
SD
It is located on a flat side near the top of the taper pin, and on the top of the bushing.
(i) If the pins or bushings have a lower strength value than 160 ksi, if they are worn into the parent metal, if they show signs of corrosion, or if they have been ground and replated, prior to further flight, remove the discrepant part(s) and replace it with a new FAA-approved part(s). Reworked parts are not acceptable for use as replacement parts.
(ii) Prior to installing any FAA-approved new taper pin or split sleeve bushing on the airplane, perform a hardness test on the part(s) and ensure that the equivalent strength value is between 160 and 180 ksi. Parts having a strength value lower than 160 ksi shall not be installed. Taper pins and split sleeve bushing received directly from Convair and bearing the Convair mark are excluded from this requirement.
(b) 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, Los Angeles Aircraft Certification Office (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, Los Angeles ACO.
NOTE: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Los Angeles ACO.
(c) Special flight permits may be issued in accordance with FAR 21.197 and 21.199 to operate the airplane to a location where the requirements of this AD can be accomplished.
(d) The inspection shall be done in accordance with General Dynamics, Convair Division, Service Bulletin 640(340D) S.B. No. 55-6, dated September 1, 1992. 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 General Dynamics, Convair Division, Lindberg Field Plant, P.O. Box 85377, San Diego, California 92138, Attention: L.J. Hayes. Copies may be inspected at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at the FAA, Los Angeles Aircraft Certification Office, 3229 East Spring Street, Long Beach, California; or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC.
(e) This amendment becomes effective on April 19, 1993.