In the late summer of 1942, his regiment was recalled from the front lines to convert to a new fighter type, the Bell P-39 Airacobra. While training in the rear, Pokryshkin frequently clashed with the regiment's new commander, Isayev (the former regimental navigator), who could not stand his criticism of Soviet air combat doctrine. Isayev fabricated a court-martial case, accusing Pokryshkin of cowardice, insubordination, and disobeying orders. Pokryshkin was grounded, removed from the regiment's headquarters, and had his Party membership cancelled. However, he was helped by his squadron mates, the regimental political commissar, and the divisional commanders, and he was soon vindicated. The 216 Fighter Aviation Division's leadership dismissed the case against him, and had him reinstated.