I have a multi commercial from FAA. Now since I cannot go back to USA, I have heard that I can fly on single as I did my private and inst. on single for recency. The difference would be that I have to take a NOC from DGCA and then fly for about 20-22 hours.
Truthfully, I've been following this post and get more confused by the minute.
If I understand correctly....
You were in the USA and obtained a Private Licence and Instrument Rating, correct?
Next, you completed a Commercial Licence with Multi Engine, correct?
If this is true, then you are perfectly within your legal rights to fly either a multi engine airplane, or a single engine airplane.
The difference is that you can not operate the single engine aircraft for "Compensation or hire," whereas you can with the multi engine.
Take a close look at your FAA licence. It probably states something to the effect of "Commercial Pilot - Multi Engine Land. Private Pilot - Single Engine Priviledges
The problem becomes that this licence is only good for USA registered aircraft unless you obtain a validation from the foreign country. For a CPL or ATPL, that's not difficult. But, I've never heard of it for a PPL, which in your case would be the qualifying licence.
My advise would be to find a FAA designated examiner in India (should be able to find one working for any number of the airlines there) and then complete the flight test for Single Engine CPL, which you can do on an any aircraft regardless of where it's registered. If you are somewhat current and have a passing mark on the PPL written exam, you could do that flight test in about two hours. This is EXACLY how I put Single Engine on my FAA licence.
Otherwise, there are several available instructors (examiners) in the UK who could do this for you. Check with any of the large flight training schools as many of them do the bi-annuals flight reviews, etc for FAA licence holders living and working there.
Hope this helps.