81-02-06 MCDONNELL DOUGLAS: Amendment 39-4020. Model DC-9 series airplane equipped with an upper main cargo door; certificated in all categories. \n\n\tCompliance required as indicated, unless already accomplished. \n\n\tTo prevent stress corrosion of the upper cargo door spool fitting attach bolts accomplish the following: \n\n\t(a)\tFor fuselage numbers 0 through 675, within 12 months after the effective date of this AD, inspect, lubricate, replace as necessary, and seal the latch spool fitting attach bolts in accordance with a method approved by the Chief, Los Angeles Area Aircraft Certification Office, FAA Northwest Region. (NOTE: Douglas Aircraft Company Service Bulletin DC-9 SB 52-119, dated October 28, 1980, has been approved as a means of compliance with this requirement.) \n\n\t(b)\tFor fuselage numbers 676 and subsequent and those airplanes modified in accordance with Douglas Aircraft Company DC-9 AOL 9-833A, dated April 2, 1979, within 24 months after the effective date of this AD, inspect, lubricate, replace as necessary, and seal the upper cargo door latch spool fitting attach bolts in accordance with a method approved by the Chief, Los Angeles Area Aircraft Certification Office, FAA Northwest Region. (NOTE: Accomplishment of the instructions set forth in Part 2, Group II, Paragraph C of Douglas Aircraft Service Bulletin DC-9 SB 52-119 has been approved as a means of compliance with this requirement.) \n\n\t(c)\tSpecial flight permits may be issued in accordance with FAR 21.197 and 21.199 to operate airplanes unpressurized to a base for the accomplishment of inspections/modifications required by this AD. \n\n\tThis amendment becomes effective April 1, 1981.