73-26-06: Corrosion Of Torsion Shafts

73-26-06 BOEING: Amdt. 39-1762. Applies to all Model 727 airplanes, certificated in all categories, listed in Boeing Service Bulletin 727-32-203, Revision 3, dated November 21, 1973, or later FAA approved revisions. \n\tA.\tFor reworked torsion shafts which were not plated in a manner to provide corrosion protection as specified in Boeing Service Bulletin 727-32-203, Revision 3, dated November 21, 1973, within the next 750 landings after the effective date of this AD, unless already accomplished within the last 750 landings, and thereafter at intervals not to exceed 1500 landings since the last such inspection, inspect the shafts for cracks in accordance with such service bulletin or later FAA approved revisions. Shafts found cracked are to be replaced prior to further flight with one of the following, any one of which is terminating action. \n\t\t1)\tA shaft P/N 65-18949-1 which has never been reworked; or \n\t\t2)\tA shaft P/N 65-18949-1 which has been reworked in accordance with BoeingService Bulletin 727-32-203, Revision 3, dated November 21, 1973, or later FAA approved revisions; or \n\t\t3)\tA shaft (P/N 65-18949-1) which has been reworked in a manner approved by the Chief, Engineering and Manufacturing Branch, FAA Northwest Region; or \n\t\t4)\tA newly designed shaft as specified in and installed in accordance with Boeing Service Bulletin 727-32-205, dated March 14, 1973, or later FAA approved revisions. \n\tB.\tPrior to accumulation of 8,000 landings on a reworked torsion shaft which was not plated in a manner to provide corrosion protection, as specified in Boeing Service Bulletin 727- 32-203, Revision 3, dated November 21, 1973, or within the next 3,000 landings time in service after the effective date of this AD, whichever occurs later, replace the shaft with one of those described in A(1), A(2), A(3), or A(4). \n\tC.\tFor the purpose of this AD, when conclusive records are not available to show the number of landings accumulated by a particular shaft, the number oflandings may be computed by dividing the airplane time in service since the shaft was installed in the airplane by the operator's fleet average time per flight for his Model 727 airplanes. \n\tD.\tUpon request of the operator, an FAA maintenance inspector, subject to prior approval of the Chief, Engineering & Manufacturing Branch, FAA Northwest 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 that operator. \n\n\tThis Amendment becomes effective upon publication.