50-43-01 DOUGLAS: Applies to All Model DC-6 Aircraft. \n\n\tTo be accomplished on or before the next major inspection where facilities are available and in any event by December 15, 1950, unless already accomplished at last previous tire change, and thereafter at the regular major inspection nearest to 330 hours. This inspection period may be extended to tire replacement periods by the assigned CAA Agent when the airline's service experience indicates that a satisfactory level of safety is being maintained. \n\n\tRemove the tires from all Goodyear main wheels, Model L20HBMF, wheel assemblies 9540049 and 9540332, and thoroughly inspect by Zyglo or equivalent methods the critical areas of the wheel, such as: \n\n\t1.\tBrake drive flange area. \n\n\t2.\tTire bead radius of the fixed flange. \n\n\t3.\tTire bead seat radius of the demountable flange. \n\n\t4.\tRadius of the demountable flange step. \n\n\t5.\tThe flange returning ring groove in the wheel. \n\n\tIf cracks are found in any of the critical areas at one of these inspections, the wheel should be retired from service.