This paper addresses formal verification of intermittent fault diagnosability in Discrete Event Systems (DESs). The system is modeled by a Finite State Automaton and intermittent faults are defined as faults that can automatically recover once they have occurred. Two definitions of diagnosability, regarding the detection of fault occurrences within a finite delay and the detection of fault occurrences before their recovery, are discussed. The diagnosability is analyzed on the basis of the twin-plant structure, which is formally modeled as a Kripke structure, while diagnosability conditions are formulated using LTL temporal logic. We focus on a practical application of this approach, namely a case-study from the railway control field, will serve as a benchmark to illustrate the various developed mechanisms and to assess the scalability of the technique.