How many marks do I need to get in the Mains for aerospace engineering at PEC?

If you are an out-of-state aspirant, your JEE Main ranking must be around the opening and closing range of 2936 - 12187. If you belong to the home state then your rank must fall under 14665 - 31620. To fall under this range you must score around 150 marks. 

If you are interested in Aerospace Engineering irrespective of the college, then you must consider IIST Thiruvananthapuram too. It offers aerospace engineering as its flagship course for which you must aim for around 4K rank in JEE Main by scoring 260+

PEC is still an amazing option for AE. If you score 150-200 in JEE Main, your seat will be almost sorted at PEC in their first round of counseling.