  We build up a new phenomenological framework associated with a minimal
generalization of Einsteinian gravitation theory. When linearity, stationarity
and isotropy are assumed, tests in the solar system are characterized by two
potentials which generalize respectively the Newton potential and the parameter
$\gamma $ of parametrized post-Newtonian formalism. The new framework seems to
have the capability to account for the Pioneer anomaly besides other gravity
tests.
