AD 80-12-02 R1

80-12-02 R1 MCDONNELL DOUGLAS: Amendment 39-3785 as amended by Amendment 39-5499. Applies to McDonnell Douglas Model DC-6, -6A, -6B, R6D, and C-118 (Military) series airplanes, certificated in any category, with 30,000 hours or more total time-in-service. Compliance required as indicated, unless previously accomplished.

To prevent loss in strength capability of the wing due to lower wing fitting, stringer and skin cracks, accomplish the following:

(a) Within the next ten hours' time in service after the effective date of this AD, or within 25 hours' time in service from the last inspection conducted in accordance with this paragraph and thereafter at intervals not to exceed 25 hours' time in service, until inspected in accordance with paragraph (c), inspect by dye penetrant or equivalent the left and right hand wing lower surface six inches inboard and outboard of wing stations 96, 127, 138 and 179 from the front spar to the center spar.

(b) If cracks are found, before further flight,

(1) Accomplish the inspection required by paragraph (c), and

(2) Repair cracks in accordance with Douglas Structural Repair Manual or other repair data approved by the Manager, Los Angeles Aircraft Certification Office, FAA, Northwest Mountain Region.

(3) At intervals not to exceed 500 hours' time in service from the last inspection in accordance with paragraph (c) repeat the inspections required by paragraph (c).

(c) Within 100 hours' time in service after the effective date of this AD, unless previously accomplished within the last 400 hours' time in service and thereafter at intervals not to exceed 500 hours' time in service from the last inspection required by this paragraph, using procedures approved by FAA Principal Maintenance Inspector,

(1) Inspect by X-ray the left and right wing lower skin, stringers, and fittings between wing station 60 to 130 and 167 to 185, from the front spar to the center spar; and inspect by X-ray the wing skin that lies beneath the skate angle at wing station 130 at the inboard edge of the inboard nacelle, both left and right wing, in accordance with Douglas Aircraft Company Report MDC-J1946, "NDI Inspection Techniques for DC-6 Lower Wing Skin at Station 130," Revision "A", dated July 26, 1985, or later revision approved by the Manager, Los Angeles Aircraft Certification Office, FAA, Northwest Mountain Region.

(2) Clean and visually inspect with a 4X magnification in the nacelle area internally between wing stations 130 and 167, from the front spar to the center spar, and

(3) Clean and inspect by dye penetrant or equivalent external skin surface six inches inboard and outboard of wing station 96, from the front spar to the center spar.

(4) The interval for conducting the X-ray inspection in paragraph (c)(1), above, may be extended from 500 to 1000 hours time-in-service from the last X-ray inspection, provided that the visual inspection specified in paragraph (c)(2),above, is extended to cover wing stations 60 to 185 from the front spar to the center spar, when the X-ray inspection is not accomplished.

(5) Repair cracks prior to further flight in accordance with Douglas Structural Repair Manual or other repair data approved by the Manager, Los Angeles Aircraft Certification Office, FAA, Northwest Mountain Region.

(d) Alternate means of compliance which provide an acceptable level of safety may be used when approved by the Manager, Los Angeles Aircraft Certification Office, FAA, Northwest Mountain Region.

All persons affected by this directive who have not already received the appropriate service documents from the manufacturer may obtain copies upon request to McDonnell Douglas Corporation, 3855 Lakewood Boulevard, Long Beach, California 90846, Attention: Director, Publications and Training, Cl-750 (54-60). These documents may be examined at the FAA, Northwest Mountain Region, 17900 Pacific Highway South, Seattle, Washington, orthe Los Angeles Aircraft Certification Office, 4344 Donald Douglas Drive, Long Beach, California.

Amendment 39-3785 superseded emergency telegraphic AD T80WE-18.

Amendment 39-3785 became effective June 9, 1980.

Amendment 39-5499 became effective January 28, 1987.

This action corrects Amendment 39-5499 (51 FR 46602; December 24, 1986).

This correction becomes effective April 21, 1987.