PBM-3D flying boat with search radar housing above the forward fuselage anchored on the water
The PBM-3D was a significantly improved aircraft designed specifically for the Pacific theater of war against Japan. This version boasted increased defensive armament, with a 12.7 mm gun in the nose, tail, and dorsal turrets, as well as one in each waist position. The engines were upgraded to the R-2600-22 model, which produced 1,900 hp and drove improved four-bladed propellers. Unfortunately, the first batch of engines had unreliable valve seals. As the Mariner planes would be flying over long distances in the Pacific, the crew armor was increased, and the fuel tanks were changed to the self-sealing type. In addition to its normal offensive weaponry, the PBM-3D was capable of carrying a Mk XIII torpedo between the engine nacelle and fuselage. To combat the exceptionally hot weather in the Pacific, cooling fans were added to the engines as the campaign progressed. A total of 260 PBM-3Ds were delivered, all of which were equipped with the APS-15 radar system above the cockpit. The first deliveries of the PBM-3D were made in late 1943 to VP-202, based in Breezy Point, Norfolk, Virginia, but the unit was quickly sent to the Pacific theater at the beginning of the following year. Two more units, VP-16 and VP-216, were ready for action in the Pacific by the time of the invasion of Saipan in June 1944.