In this paper we present a model based solely on isospin for the determination of ratios of pion absorption cross sections on three nucleons. We then compare the results with the available experimental data for pion absorption on He-3 and He-4, at the energies 120 and 165 MeV, and for Li-6 and Li-7 at 50, 100, 140, and 180 MeV. Good agreement was found between this simple model and experiment,
... [Show full abstract] suggesting that pion absorption on three nucleons in light nuclei may be described as a one-step process.