62-10-01: Elevator Modification

62-10-01 BELL: Amdt. 428 Part 507 Federal Register April 21, 1962. Applies to All Model 47J Helicopters Serial Numbers 1420 Through 1802 With Rollpins P/N 49-040-187-1750 or Clevis Pins P/N MS 20392-2-49 Installed In Elevator Spar, and With End Rib P/N 47-267- 453-1 (0.025-Inch Thick) Installed; Except Those Helicopters That Have Bell Kit No. 47-3746-1 or 47-3746-2 Installed. Compliance required as indicated. Numerous reports have been received of fatigue cracking of the tubular spar of both the right and left elevator at the Rollpin hole at B.L. 7.0, and fatigue cracking of the inboard rib of the elevators. To preclude failure of the elevator, the following shall be accomplished: (a) Within 25 hours' time in service after the effective date of this AD: (1) Remove the elevators from the tail boom in accordance with the Bell Maintenance Manual. (2) Clean the area around the Rollpin hole and remove any zinc chromate putty from any plugged hole in the tubular spar at B.L. 7.0 for both right and left elevators. (3) Inspect for cracks in the tubular spar of both elevators at the Rollpin hole at B.L. 7.0 using a 5-power or higher magnifying glass. (4) Inspect the inboard rib for cracks using a 5-power or higher magnifying glass. (b) If cracks are found in the tubular spar modify the elevator with Bell Helicopter Kit No. 47-3746-1 or 47-3746-2, "Improved Design Synchronized Elevator," or FAA engineering approved equivalent prior to further flight. (c) If no cracks are found in the tubular spar, install clevis pin in accordance with subparagraphs (1) through (4) or Bell Service Letter No. 56 and reinspect in accordance with subparagraph (5). (1) Position coupling assembly P/N 47-267-483-1 on elevators and line drill through Rollpin holes with a "D" (0.2460-inch diameter) drill. Remove sharp edges from holes. Install MS 20392-3-49 clevis pins, AN 960-4162 washers, and AN 381-3-6 cotter pins. A finger tight slip fitof the clevis pins is desired, approximately 0.0005 inch loose. (2) Reinstall the elevator on the helicopter, shim as required to prevent preload or end play at bearings. (3) Check clearance between skin and end of clevis pins. Trim skin, if necessary, to obtain clearance. (4) Rerig elevator in accordance with the Bell Maintenance Manual. (5) Reinspect in accordance with (a)(1) through (a)(3) within each succeeding 50 hours' time in service until Bell Helicopter Kit No. 47-3746-1 or 47-3746-2, "Improved Design Synchronized Elevator", or FAA approved equivalent is installed. (d) If cracks are found in the inboard rib, repair the elevator as specified below, or modify with Bell Helicopter Kit No. 47-3746-1 or 47-3746-2, or FAA engineering approved equivalent prior to further flight. (1) Remove the inboard rib by drilling out the rivets and remove the Bell P/N 47-267-404-7 shoulder from the rib by drilling out the rivets. (2) Add a doubler of 0.032 thickness, or a new rib of 0.032 thickness, material aluminum alloy 2024-0, or a Bell rib P/N 47-267-453-7 (one required per elevator). (3) Rivet Bell P/N 47-267-404-1 shoulder to the old rib and new doubler or the new rib. Use the rivet pattern in the shoulder with AN 470-AD3 or -4 rivets. (4) Install the rib assembly, using the rivet pattern in the elevator skin with MS 20600 AD4 or -5 rivets. (e) If no cracks are found in the inboard rib: (1) Reinstall the elevator on the helicopter in accordance with Bell Maintenance Manual. (2) Reinspect rib for cracks in accordance with (a)(4) within each succeeding 50 hours' time in service until Bell Helicopter Kit No. 47-3746-1 or 47-3746-2, "Improved Design Synchronized Elevator", or FAA engineering approved equivalent is installed. (f) Upon request of the operator, an FAA maintenance inspector subject to prior approval of the Chief, Engineering and Manufacturing Branch, Southwest 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. (Bell Service Bulletin No. 135 SB dated July 27, 1961, covers this same subject. Bell's Service Letter No. 56 covers an acceptable fix for paragraphs (c)(1) through (c)(4) of this AD.) This directive effective May 22, 1962.