The UF-XS, seen at the Kohnan plant early in its test programme, was a rebuilt UF-1 Albatross which served as a flying scale model of the PS-1 and as a test-bed for the boundary layer control system and other features adopted for the Shin Meiwa flying boat.
The third US-1, MSDF 9073, delivered in December 1975, seen in formation with the second aircraft, MSDF 9072, enabled the 71st Koku-tai to be formed at Iwakuni on 1 July 1976, with a preliminary three-aircraft inventory.
The PS-1 (MSDF 5813 being illustrated) has established an excellent service record over a decade of service and attrition suffered by the 31st Koku-tai has in no case been the result of any design or structural shortcoming. Nevertheless, all flying boats of this type are to be retired from the MSDF inventory by 1989.
All US-1 amphibians (MSDF 9073 being illustrated) are now being fitted with uprated T64-IHI-10J turboprops as they are returned to the Kohnan factory for overhauls.
The last of the initial batch of 12 production PS-1 flying boats ordered under the 3rd Defence Build-up Programme, this particular aircraft being delivered to the MSDF early in 1974.
The first full series production PS-1 photographed in October 1972, shortly before delivery to the MSDF
The second prototype PS-1 seen at Iwakuni on 18 May 1970, during evaluation by the 51st Flight Test Squadron. Note the underwing pods for paired homing torpedoes between the engine nacelles.
PS-1 flying boats of the 31st Koku-tai at Iwakuni, near Hiroshima, the flying boat in the foreground being the first pre-series aircraft.
The first US-1 amphibian, MSDF 9071, seen during its initial flight test programme, late 1974
The first prototype PS-1 (MSDF 5801) which commenced its flight test programme on 5 October 1967. Service trials with this boat were initiated at Iwakuni in August 1968.
The second US-1, MSDF 9072.
The flight deck of the US-1. Pilots of the 71st Koku-tai, the MSDF user squadron of this large amphibian, are unanimous in their praise for its ease of handling and excellent reliability.
The general arrangement drawing depicts the US-1 amphibian.