I am retired from ABF Freight as a driver. When a repair is done to an aircraft do any of the people work under the license of someone else? Is it common for a person who has not achieved their Master Certification to work under another license. And does UPS outsource any of their repair to South America, rather than have it done in the states? And, if a mechanic signs of on work another person did, & it is allowed by the rules & reg's, how could it effect his or hers license? Thank you.