safriz Well-Known member Jan 1, 2018 1,350 399 UK, Pakistan Jan 7, 2020 #1 What is this? It's on all J-10B and c , and now on JF-17 BLOCK III. Some say it's an air inlet for an APU? But that's an odd place for mounting an API and it doesn't look like an air inlet? Plus if it's an APU where is the exhaust?