CPL/ATPL pilot having a A/P mechanic license? can possibly perform a maintenance check?

Question

can i ask if a person having a CPL/ATPL license and also a A/P mechanic license holder at the same time (Dual license)

can possibly perform a maintenance in their aircraft?

specially in large aircraft(boeing, airbus)

Answer 1

If you work for an airline, you can only do one or the other.  To work on your company's aircraft, you have to be trained by your company, and perhaps even the company that manufactured the aircraft.  To fly the aircraft, you have to be trained by your airline to fly it.  Few companies would train the same person to do both, as they wouldn't get enough use out of them.  Training is expensive, so they have different people to do different jobs.

Answer 2

For small aircraft yes they can.  Even non-mechanics can preform limited preventative maintanence on a plane, but the major inspections like a 100 hr. or annual an a&p rated mechanic must do.  Major repairs have to get signed off by an A&P with and IA(inspection authorization)rating, which an a&p mechanic can get after 3 years working as a mechanic.  There are some(few) pilot/A&P jobs out there that require both ratings.  For a nice big boeing the pilots are pilots and the mechanics are mechanics, no pilot(even with an A&P rating) is gonna get out and grease bearings or balance a rudder on that monster.  They leave that to the guys that do it day in and day out.