Catalyzes the reduction of saturated fatty acyl-CoA to fatty alcohols. The preferred substrates are C24:0 and C26:0. Necessary for the final stages of tracheal maturation, to facilitate the transition from water-filled to gas-filled tubes. May help to maintain the integrity of the outer hydrophobic envelope of the trachea. a long-chain fatty acyl-CoA + 2 H(+) + 2 NADPH = a long-chain primary fatty alcohol + CoA + 2 NADP(+) Detected in the tracheal system and hindgut from embryonic stage 13 onwards (at protein level). Tracheal morphogenesis in embryos is grossly normal. The tracheal tubes fail to fill with gas during the final stages of maturation, and instead remain full of fluid. The hydrophobic outer cuticle layer of the trachea appears to be disrupted and forms membranous structures extending into the tracheal lumen. Belongs to the fatty acyl-CoA reductase family.