64-09-02 BOEING: Amdt 717 Part 507 Federal Register April 21, 1964. Applies to All Models 707 and 720 Series Aircraft. \n\n\tCompliance required as indicated. \n\n\tThere have been instances of above normal control column forces and sluggish airplane response. In all cases, the airplanes involved had been exposed to heavy rain prior to takeoff or had taken off in heavy rain, with comparatively low freezing altitudes prevailing. This can result in ice formation in the elevator balance panel hinge or around the balance panel track grip. \n\n\tIn order to preclude this unsafe condition, accomplish the following: \n\n\tWithin 600 hours' time in service after the effective date of this AD, and thereafter at intervals not exceeding 1,200 hours' time in service, accomplish the following or equivalent approved by Engineering and Manufacturing Branch, FAA Western Region: \n\n\t(a) Mix MIL-G-25760 or MIL-G-7118 grease or equivalent approved by Engineering and Manufacturing Branch, FAA WesternRegion, with Methyl Ethyl Ketone or aliphatic naptha (Varsol), or equivalent approved by Engineering and Manufacturing Branch, FAA Western Region, to a consistency suitable for application with a squirt type oil can, and apply a good coverage of lubricant to the following areas: \n\n\t\t(1) Upper surface of the piano hinge for each balance panel, and \n\n\t\t(2) On either side of both balance panel track grips. \n\n\t(b) Upon request of the operator, and FAA maintenance inspector, subject to prior approval of the Chief, Engineering and Manufacturing Branch, FAA Western Region, may adjust the repetitive intervals specified in this AD to permit compliance at an established inspection period of the operator if the request contains substantiating data to justify the increase for such operator. \n\n\t(Boeing Service Bulletins Nos. 1865 and 1865A cover this same subject.) \n\n\tThis directive effective May 19, 1964. \n\n\tRevised September 5, 1964.