Fatty acyl-coenzyme A (CoA) diphosphatase that hydrolyzes fatty acyl-CoA to yield acyl-4'-phosphopantetheine and adenosine 3',5'-bisphosphate (By similarity). Preferentially hydrolyzes unsaturated long-chain acyl-CoA substrates in the endoplasmic reticulum (ER) lumen (By similarity). This catalytic activity is required for maintaining ER structure and for lipid droplets (LDs) biogenesis, which are lipid storage organelles involved in maintaining lipid and energy homeostasis (PubMed:28067622) (By similarity). May directly bind to diacylglycerol (DAGs) and triacylglycerol, which is also important for LD biogenesis (By similarity). May support directional budding of nacent LDs from the ER into the cytosol by reducing DAG levels at sites of LD formation (By similarity). Plays a role in the regulation of cell morphology and cytoskeletal organization (PubMed:28067622) (By similarity). Required for correct morphology of nociceptive multi-dendritic sensory neurons (PubMed:28067622). Required for normal mechanical amplification in hearing (PubMed:28067622). an acyl-CoA + H2O = adenosine 3',5'-bisphosphate + an acyl-4'-phosphopantetheine + 2 H(+) RNAi-mediated knockdown results in loss of auditory sensitivity (PubMed:28067622). In the whole body or specifically in muscle cells or fat body, results in locomotor impairment, uncontrolled and uncoordinated wing movements leading to flightless phenotype (PubMed:28067622). In nociceptive dorsal class IV dendritic arborization C (ddaC) neurons results in altered branching and dendritic field coverage in third instar larvae (PubMed:28067622). In fat body reduces lipid droplet size with aging (PubMed:28067622). In all neurons does not show any of the phenotypes above (PubMed:28067622). Belongs to the FIT family. FIT2 subfamily.