How could a 45 years old DC10 be still in service with one of the largest cargo airline? It is amazing to see this 45-year-old DC10 freighter still operating for FedEx regularly:



I know the lifespan of an aircraft is not rated by ages but flight cycles, but an actively used DC10 over 45 years must have exceeded the designed flight cycle right?  However, I regularly come across 30+ or even 40+ years old aircrafts on FR24 that are still in service, mostly freighter though. Wouldn't they raise any safety concerns? Besides, how could airlines operate them efficiently?
The DC-10’s have all been converted from DC-10’s to MD-10’s. The last conversion was in 2007, I believe. The entire aircraft wiring was replaced, the avionics package converted to glass cockpit and other structural work was also performed. As a result, the airframe was “zero houred” upon completion of the conversion.

Although they’re getting older, they’re still warhorses and their reliability is still good. 

Also, cargo operators don’t put nearly as many cycles on their aircraft as passenger carriers. As a result, there is a lot less wear and tear on the aircraft.