81-02-07 McDONNELL DOUGLAS: Amendment 39-4021. Applies to all Model DC-10 series airplanes certificated in all categories. Compliance required as indicated, unless already accomplished. To prevent stress corrosion cracking of the upper and lower cargo door spool fitting attach bolts accomplish the following: \n\n\tA.\tFor fuselages 1-125, within 12 months after the effective date of this AD, inspect, lubricate, replace as necessary, and seal the 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 Figure 1 of Douglas Aircraft Company Service Bulletin DC-10 SB 52-183, dated October 28, 1980, has been approved as a means of compliance with this requirement.) \n\n\tB.\tFor fuselage 126 and subsequent, within 24 months after the effective date of this AD, inspect, lubricate, replace as necessary and seal the 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 Company Service Bulletin DC-10 SB 52-183, dated October 28, 1980, has been approved as a means of compliance with this AD.) \n\n\tC.\tSpecial flight permits may be issued in accordance with FARs 21.197 and 21.199 to operate airplanes unpressurized to a base for the accomplishment of inspections/modifications required by this AD. \n\n\tD.\tAlternative inspections, modifications, or other actions which provide an equivalent level of safety may be used when approved by the Chief, Los Angeles Area Aircraft Certification Office, FAA Northwest Region. \n\n\tThis amendment becomes effective April 1, 1981.