AD 81-22-01

81-22-01 McDONNELL DOUGLAS: Amendment 39-4244. Applies to all McDonnell Douglas Model DC-9-80 Series airplanes, certificated in all categories.

Compliance required as indicated in the body of this AD, unless previously accomplished. To prevent failure of the slat drive mechanism, accomplish the following:

A. Upon the accumulation of 600 landings, or within the next 200 landings after the effective date of this AD, whichever occurs later perform a one-time inspection of the slat control valve assembly to verify "correct" flow direction installation of check valves and restrictors as shown on Douglas Service Sketch 3303 of Douglas DC-9 Super 80 Alert Service Bulletin A27-225, Revision 1, dated September 22, 1981, or later revisions approved by the Chief, Los Angeles Area Aircraft Certification Office, FAA, Northwest Mountain Region. Correct the installation of check valve/restrictor if necessary.

NOTE: Directional arrow on restrictors and check valves may be in a position requiring additional visual aids to view.

B. If slat control valve assembly check valves and restrictors are installed properly, no further action is required.

C. If slat control valve assembly check valves and/or restrictors were improperly installed, accomplish the following in accordance with Douglas DC-9 Super 80 Alert Service Bulletin A27-225, Revision 1, dated September 22, 1981, or later revisions approved by the Chief, Los Angeles Area Aircraft Certification Office, FAA Northwest Mountain Region, unless already accomplished:

1. Perform dye penetrant or eddy current inspections of the slat drive cylinder support brackets per Paragraph 2.E of the service bulletin.

2. Conduct a visual inspection of the slat drive mechanism per Paragraph 2.F of the service bulletin.

3. If no cracks or other indications of distress are detected, conduct repetitive inspections per Paragraph 2.G of the service bulletin, at intervals not to exceed 350 landings.4. If cracked or failed support brackets or other indications of distress in the slat drive mechanism are detected, remove the slat drive mechanism per Paragraph 2.H of the service bulletin.

5. Replace cracked support brackets per Paragraph 2.I of the service bulletin.

6. If a slat drive cylinder support bracket is failed, or other indications of distress are detected, accomplish the following:

a. Inspect and repair per the instructions of paragraph 2.J(1) of the service bulletin.

b. Inspect wing spar per the instructions of paragraph 2.J(2) of the service bulletin.

7. If inspection of the wing spar reveals any indication of damage, repair in a manner approved by the Chief, Los Angeles Area Aircraft Certification Office, FAA Northwest Mountain Region.

8. Install repaired slat drive mechanism per the installation instructions of Paragraph 2.K of the service bulletin.

9. For slat drive mechanisms which have not had both slat drive support cylinder support brackets replaced, conduct repetitive inspections per paragraph C.3 of this AD.

10. Installation of new slat drive cylinder support brackets terminates the requirements for repetitive inspections per this AD.

D. Special flight permits may be issued in accordance with FARs 21.197 and 21.199 to operate airplanes to a base in order to comply with the inspection requirements of this AD.

E. If the number of landings on an aircraft is not known, for the purpose of complying with this AD, subject to acceptance by the assigned FAA maintenance inspector, the number of landings may be determined by dividing the airplane's hours time in service by the operator's fleet average time from takeoff to landing for the airplane type.

F. Alternative means of compliance with this AD which provide an equivalent level of safety may be used when approved by the Chief, Los Angeles Area Aircraft Certification Office, FAA, Northwest Mountain Region.

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 the McDonnell Douglas Corporation, 3855 Lakewood Boulevard, Long Beach, California 90846, Attention: Director, Publications and Training, C1-750 (54-60). These documents also may be examined at FAA Northwest Mountain Region, 9010 East Marginal Way South, Seattle, Washington 98108, or 4344 Donald Douglas Drive, Long Beach, California 90808.

This amendment becomes effective November 5, 1981.