  Time-dependent spherically-symmetric perturbations of Schwarzschild black
holes are studied within torsion bigravity, i.e., within generalized
Einstein-Cartan theories where the dynamical torsion carries massive spin-2
excitation. We reduce linearized perturbations to a Zerilli-like equation. The
structure of the potential entering the latter Zerilli-like equation has two
important consequences. First, in order to avoid the presence of singularities
in generic perturbations, one must restrict the range (or inverse mass) of the
spin-2 excitation to be (essentially) smaller than the radius of the considered
black hole. Second, we then show that the Schwarzschild black hole is linearly
stable against spherically-symmetric perturbations.
