AD 88-04-01

88-04-01 MCDONNELL DOUGLAS: Amendment 39-5845. Applies to McDonnell Douglas Model DC-6, -6A, -6B, R6D, and C-118A series airplanes, certificated in any category. Compliance required as indicated, unless previously accomplished.

To detect cracks and prevent failure of the vertical stabilizer rear spar attach fittings, accomplish the following:

A. Within the next 3 months after the effective date of this AD, unless already accomplished within the last 9 months, and thereafter at intervals not to exceed one year or before further flight, whichever occurs later, inspect the vertical stabilizer rear spar attach fittings, front and rear, right and left, in accordance with Douglas DC-6 Service Bulletin 723, dated May 27, 1957, or later revisions approved by the Manager, Los Angeles Aircraft Certification Office, FAA, Northwest Mountain Region, After each inspection, apply LPS-3 corrosion inhibiting oil, or equivalent, to each fitting.

B. If a crack is found, accomplish the following:

1. Replace the fitting(s) before further flight for each of the following conditions:

a. a crack is found that matches the description in paragraph 1. of Douglas DC-6 Service Bulletin 723, dated May 27, 1957, or later revisions approved by the Manager, Los Angeles Aircraft Certification Office, FAA, Northwest Mountain Region;

b. more than 1 fitting per airplane is cracked;

c. the crack is chordwise.

2. Replace the fitting within the next 3 months after the crack is found, or before further flight, whichever occurs later, if the crack matches the description of paragraph 2. of Douglas DC-6 Service Bulletin 723, dated May 27, 1957, or later revisions approved by the Manager, Los Angeles Aircraft Certification Office, FAA, Northwest Mountain Region.

C. 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.

D. Special flight permits may be issued in accordance with FAR 21.197 and 21.199 to operate the airplane to a base to comply with the repair requirement of this AD 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 information from the manufacturer may obtain copies upon request to McDonnell Douglas Corporation, 3855 Lakewood Boulevard, Long Beach, California 90846, Attention: Director of Publications, C1-L00 (54-60). These documents may be examined at the FAA, Northwest Mountain Region, 17900 Pacific Highway South, Seattle, Washington, or the Los Angeles Aircraft Certification Office, 4344 Donald Douglas Drive, Long Beach, California.

This Amendment becomes effective March 21, 1988.