74-08-06 DOUGLAS AIRCRAFT: Amendment 39-1810 as amended by Amendment 39-1855. Applies to Model DC-10, Series 10, 30, and 40 airplanes with the factory serial numbers as indicated in Douglas Alert Service Bulletin No. A32-82, dated May 13, 1974, or later FAA-approved revisions. \n\n\tCompliance required as indicated. \n\n\tTo prevent a failure to actuate of the landing gear alternate freefall system caused by a jamming of the landing gear control valve slide, Part No. AYG7043-1, in the sleeve, Part No. AYG 7039-1, accomplish the following: \n\n\t(a)\tBeginning with the effective date of this AD, on each day in which the aircraft is used, and after any use of the alternate gear extension handle, check the bypass control crank for freedom of movement. The landing gear control valve, Part No. AYG7050, is located in the right hand wheel well, forward center panel of the keel webb. The bypass control crank is next to the keel webb on the forward lower end of the valve. Freedom of movement of the bypass valve is verified by manually moving the crank up and down. If the crank cannot be moved freely by hand, free the crank by exerting a downward force. The downward force exerted must not be excessive. If the crank freedom of movement is not achieved, replace the landing gear control valve, Part No. AYG7050, prior to further flight. Continue these checks for crank freedom of movement until a stop is installed on the landing gear control valve in accordance with Douglas Alert Service Bulletin No. A32-76, Revision 1, dated March 1, 1974, and Douglas Alert Service Bulletin No. A32-82, dated May 13, 1974, or later FAA-approved revisions. Incorporation of both service bulletins is required. \n\n\t(b)\tWithin the next 1500 hours in service after the effective date of this AD, unless previously accomplished, install a stop on the landing gear control valve, Part No. AYG7050, in accordance with Douglas Alert Service Bulletin No. A32-76, Revision 1, dated March 1, 1974, and Douglas Alert Service Bulletin No. A32-82, dated May 13, 1974, or later FAA-approved revisions. Incorporation of both service bulletins is required. This installation of an external stop on the valve housing will prevent the lever moving to a point that would allow internal jamming. \n\n\t(c)\tWithin 24 hours after the effective date of this AD unless previously accomplished, conduct an inspection of the landing gear control valve stop clearance as prescribed in Phase I of Douglas Alert Service Bulletin No. A32-82, dated May 13, 1974, or later FAA-approved revisions if the landing gear control valve stop has been installed as required by paragraph (b) of this AD. If the clearance is .050 inch or less, Phase II of the Douglas Alert Service Bulletin No. A32-82 must be accomplished prior to next flight. \n\n\t(d)\tThe Chief, Aircraft Engineering Division, FAA Western Region, may approve equivalent inspection procedures or modifications. \n\n\t(e)\tAircraft may be operated to a base for accomplishment of the maintenance required by this AD per FAR's 21.197 and 21.199. \n\n\tAmendment 39-1810 became effective April 8, 1974. \n\n\tThis amendment 39-1855 becomes effective June 3, 1974.