Hall XPTBH The Hall XPTBH was a prototype American twin - engined seaplane , submitted to the United States Navy by the Hall Aluminum Aircraft Corporation in response to a 1934 specification for new bomber and scout aircraft . Constructed in an innovative fashion that made extensive use of aluminum , the XPTBH proved successful in flight testing , but failed to win favor with the U . S . Navy . No production contract was awarded , and the single aircraft built served in experimental duties before its destruction in a hurricane during 1938 . Design and development . In late 1934 , the U . S . Navy ' s Bureau of Aeronautics ( BuAer ) issued a specification for new scout bomber and torpedo bomber designs . Eight companies submitted a total of ten designs in response , evenly split between monoplanes and biplanes . The Hall Aluminum Aircraft Company submitted the only seaplane design ; a single prototype was ordered by the Navy for evaluation on June 30 , 1934 . Given the designation XPTBH - 1 , it became the only aircraft to receive three mission - type letters under the U . S . Navy ' s designation system used between 1922 and 1962 . Hall ' s choice of the twin - float seaplane configuration was dictated by the Navy ' s requirement that the new torpedo - bomber design should be capable of carrying a standard naval torpedo of the type carried by destroyer s . As ordered , the XPTBH - 1 was intended to be fitted with Wright R - 1820 " Cyclone " radial engines ; delays in design caused by Hall relocating their production facility , difficulties with the contract , and doubts about the aircraft ' s performance potential led to a redesign , the aircraft becoming slightly smaller and the engines being changed to a pair of Pratt & Whitney R - 1830 " Twin Wasp " radials . The changes to the aircraft resulted in it receiving the revised designation XPTBH - 2 . Utilising Hall ' s standard aluminum tubular spar , the fuselage and wing leading edges were covered in aluminum , while the rest of the wing and the control surfaces were fabric - covered . The aircraft was well - armed defensively by 1930s standards , with a powered turret , designed by Hall , mounted in the nose and carrying a single . 30 - caliber machine gun . Hand - traversed mountings for a pair of machine guns were fitted in dorsal ( top ) and ventral ( belly ) positions aft . An optically flat glass panel was fitted in the nose below the turret for use by the bombardier ; the aircraft ' s offensive weaponry , consisting of an Mark XIII aerial torpedo or , alternatively , up to of bombs , was carried in an internal bomb bay , the twin - float arrangement allowing for a clear release of the weaponry . Operational history . Delivered to the Navy on January 30 , 1937 , the aircraft was officially presented to the public at Hall ' s Bristol , Pennsylvania factory in April of that year . The aircraft ' s early flight testing , starting in February and conducted by test pilot Bill McAvoy , showed that the XPTBH had few faults , with the only significant issue being a lack of roll authority – a reduction of the ability of the ailerons to turn the aircraft – as a result of the surface area of the floats . A modification to increase the area of the rudder solved the issue . The aircraft ' s water - handling characteristics were found to be excellent ; the only significant complaints that surfaced during the testing period concerned the XPTBH - 2 ' s beaching gear , which was found to be extremely difficult to use in anything other than the calmest water . Although the XPTBH - 2 met most of its design specifications and was overall rated very good in flight testing , it failed to meet the contractual requirements for top speed and attack speed . In addition , the U . S . Navy did not consider a seagoing torpedo - bomber to be an aircraft for which there was an operational requirement ; the fact that as a floatplane the aircraft was restricted to operation from water was also considered a negative , while the aircraft ' s " three - in - one " role led it to be viewed as a jack of all trades , purpose - designed aircraft for each role being considered superior . The company , however , blamed Navy politics for the lack of a production order . Following the conclusion of its test program , the XPTBH - 2 was used for experimental duties at the Naval Torpedo Station in Newport , Rhode Island , participating in trials of aerial torpedoes . Its service at Newport came to an end on September 21 , 1938 , when the XPTBH - 2 was destroyed during the Great New England Hurricane . The XPTBH - 2 was the last aircraft designed by Hall Aluminum ; the company remained in business until 1940 , when it was bought out by Consolidated Aircraft .