81-25-04 R1 MITSUBISHI AIRCRAFT INTERNATIONAL, INC. (MAI): Amendment 39- 4274 as amended by amendment 39-4300. Applies to MAI Models MU-2B-25/-26/-26A/-40, serial numbers 313SA, 321SA, 348SA through 453SA, Models MU-2B-35/-36A/-60, serial numbers 652SA, 661SA, 697SA through 799SA, 1501SA through 1538SA, and 1540SA. \n\nCompliance is required as indicated unless previously accomplished. \n\nWithin the next 25 hours' time in service from the effective date of this AD: \n1.\tVisually inspect the engine's electrical wiring to determine if nonshielded and noncolor coded wiring is white or brown (tan). Inspection may be made at connectors P4001 and P4020. Remove spiral wrap as required for inspection. \n\n2.\tIf wires are brown (tan) inspect in accordance with Figure 1 (one) to determine if wires are "tight weave" or "loose weave." \na.\tIf brown (tan) wires are "loose weave," inspect in accordance with paragraph 4. \nb.\tIf brown (tan) wires are "tight weave," no further inspection is necessary and the airplane may be returned to service. \n\n3.\tIf wires are white, open the harness as necessary and inspect wires for identification: \na.\tIf white wires are marked MS 25471-XX (XX indicates wire gauge), inspect in accordance with paragraph 4. \nb.\tIf white wires are marked M 22759/5-XX, no further inspection is necessary and the airplane may be returned to service. \n\n4.\tAfter each 25 hours' time in service, remove wiring harness which incorporates wires affected by paragraph 2a or 3a from the engines and visually inspect all brown (tan) "loose weave" or white insulated MS 25471-XX wires for tight loop, kinks, or bulged deformation. If these conditions are found, replace the wiring harness using one of the procedures in paragraph 5 before further flight. Inspections may be discontinued when wires are replaced using one of the procedures in paragraph 5. \n\n5.\tBefore 300 hours' time in service, after the effective date of this AD, replace all brown (tan) "loose weave" orwhite insulated MS 25471-XX wires with M 22759/8-XX wire using one of the procedures specified in Part 3 of MAI S/B SB036/71-003, Revision A, or alternate means approved by the Chief, Aircraft Certification Division, Southwest Region, Federal Aviation Administration. \n\nA special flight permit may be issued in accordance with FAR 21.197 to allow flight of the airplane to a location where this AD can be accomplished. \n\nAmendment 39-4274 became effective December 10, 1981. \nThis amendment 39-4300 becomes effective January 21, 1982. \n\n\n\nAD 81-25-04