52-28-02 BELLANCA: Applies to Models 14-13, 14-13-2, 14-13-3 Aircraft, Serial Numbers Up to Number 1584.
Compliance required as soon as practicable, but not later than next engine overhaul after January 1, 1953.
In order to eliminate possible hazard due to excessive pressure from the engine-driven fuel pump, install a high-pressure relief valve between the fuel pump outlet and the inlet side of the hand wobble pump.
(Bellanca Service Bulletin No. 23 covers this same subject.)