Initial tests of the first prototype were disappointing, displaying performance only marginally better than the BH-21, even when fitted with a more powerful version of the Jupiter. Two further prototypes followed, both designated
BH-33-1, each with an increasingly powerful Jupiter variant – one a Jupiter VI, the other a Jupiter VII. The performance of the latter example was finally acceptable for the Czechoslovak defence ministry to order a small production run of only five aircraft. Three examples were sold to
Belgium, where there were plans to build the type under licence, but this did not occur. Licence production was undertaken, however, in
Poland, where a single example was sold, along with a licence to build 50 aircraft. These were designated
PWS-A and put into service with the
Polish Air Force in 1930. Development continued with an almost total redesign of the
fuselage, replacing the wooden, slab-sided structure with one of oval cross-section, built up from welded steel tubes. Designated
BH-33E, this was a world-class fighter for its time. Nevertheless, the response from the Czechoslovak military was lukewarm (although two were bought for the national aerobatics team), and Avia again looked abroad for customers, this time selling 20 aircraft to the
Kingdom of Yugoslavia, along with a licence to produce another 24. Two or three examples were also bought by
Soviet Union for evaluation. In late 1929, a further development was flown as the
BH-33L, featuring longer-span wings, and a
Škoda L W-block engine. This version finally brought the company the domestic sales that it had been hoping for, with 80 aircraft ordered by the
Czechoslovak Air Force. These became standard equipment with some air regiments up to the outbreak of
World War II. A single, final variant with a
BMW-built
Pratt & Whitney Hornet engine was built as the
BH-33H (later redesignation
BH-133) in 1930, but this did not lead to production. ==Operational history==