Factorisation of recursion operators of some Lagrangian systems

We observe that recursion operator of an S-integrable hyperbolic equation that degenerates into a Liouvile-type equation admits a particular factorisation. This observation simplifies the construction of such operators. We use it to find a new quasi-local recursion operator for a triplet of scalar fields. The method is also illustrated with examples of the sinh-Gordon, the Tzitzeica and the Lund-Regge equations.