62-08-04 BOEING: Amdt. 413 Part 507 Federal Register April 7, 1962. Applies to All Models 707 and 720 Series Aircraft Which Incorporate Magnesium Skin On the Horizontal Stabilizer Balance Panel Covers. \n\n\tCompliance required within 85 hours' time in service following the effective date of this AD unless already accomplished within the last 85 hours, and thereafter at periods not to exceed 170 hours' time in service from the last inspection. \n\n\tAs a result of cracking of the magnesium skin on the horizontal stabilizer balance panel covers the following shall be accomplished: \n\n\t(a) Conduct close visual inspection of all upper and lower horizontal stabilizer balance panel covers which incorporate magnesium skin, to detect any evidence of skin cracks. \n\n\t(b) Cracked covers must be repaired, replaced or modified in accordance with one of the following prior to further flight: \n\n\t\t(1) Repair in accordance with Structural Repair Manual Chapter 51-9-1, Chapter 51-9-2 (for fiberglass overlay panels) or later chapters, as appropriate to the airplane model involved. \n\n\t\t(2) Replace with a new standard cover incorporating magnesium skin;\n \n\t\t(3) Replace with a new standard cover incorporating aluminum alloy skin; \n\n\t\t(4) Replace with a cover incorporating honeycomb panel construction, Boeing P/N 65-28201, -28202, -28203, -28204, -28205, -28206, -28207, or -28208, as appropriate; or \n\n\t\t(5) Modify in accordance with FAA approved technical data. \n\n\t(c) When repairing any panel in accordance with (b)(1), or during inspection at major overhaul, visually inspect the bonding between the cover skin and its supporting structure for evidence of bond separation. If separation is found, repair either by tack riveting the separated parts together with 1/8 inch diameter 5056 aluminum alloy rivets at 0.60 + or - 1/32 inch spacing, or in accordance with the applicable Structural Repair Manual Set forth in (b)(1). \n\n\t(d) The repetitive inspections of any specific cover may be discontinued when the standard magnesium cover is replaced or modified in accordance with paragraphs (b)(3), (b)(4), or (b)(5). \n\n\t(e) Upon request of an operator, an FAA maintenance inspector, subject to prior approval of the Chief, Engineering and Manufacturing Branch, FAA Western Region, may adjust the repetitive inspection 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 Bulletin No. 1594 pertains to this subject.) \n\n\tThis directive effective April 7, 1962. \n\n\tRevised November 30, 1966.