An airworthiness compliance method for water-surface longitudinal stability and controllability of seaplanes

Abstract

This paper proposes a certification-oriented method for verifying the water-surface longitudinal stability and controllability of seaplanes during taxiing, take-off, alighting and water run-out. The method links regulatory requirements, hydrodynamic mechanisms, model tests and progressive flight tests into a traceable evidence chain. To make the method executable, a step-by-step procedure is defined, including test sequencing, water and loading conditions, required measurements, pilot evaluation items, safety expansion rules, stop criteria and acceptance criteria. Representative flight-test records are used to illustrate how porpoising, bouncing and wind/wave effects should be evaluated quantitatively. The results indicate that compliance should not be judged only by the occurrence of an event, but by its amplitude, growth tendency, damping, controllability, pilot workload and consistency with approved operating limitations.