"Life cycle costs." . . "Cost analysis." . . "Lubricating oils." . . "Helicopters." . . "Helicopter propeller drive." . . . . . . . . . . "Cost benefit analysis of a 9-centistoke lubricant for helicopter transmissions : under contract NAS2-14118"@en . . . . . . . . . . "Cost benefit analysis of a 9-centistoke lubricant for helicopter transmissions under contract NAS2-14118"@en . . . . . "United States. National Aeronautics and Space Administration." . . . .