To become an Aircraft maintenance engineer you need fulfill the eligibility conditions of it, which are as following:

Eligibility:
The applicant should have passed 10+2 with atleast 50% aggregate in Physics and Mathematics/Diploma in engineering/BSc with PCM.

Age:
Candidate should be between 17-24 years

In to order to Aircraft maintenance engineer you can join Aeronautical related companies like:

HAL,
NAL etc.

In these companies you can work as a technician or an inspector in some specialized area