A mechanical accident generates human and/or material losses, in general. Its cause may or may not blame individuals involved in the operation of that system, whether in design, manufacture and assembly, or in periodic inspection, or even in its use. Once the case has been judicialized, if there are no witnesses, or if there are, but with conflicts of interest, the Forensic Engineer enters the scene and, taking knowledge of what is known a posteriori of the fact, will link to this information the history of the life that the residue material has registered itself, and will produce a report with a technical opinion of what seems to have occurred. Therefore, a good Forensic Mechanical Engineer must also be a good student of Fractography, that is, the analysis of fracture characteristics and the probable causal link between the mechanism causing the component fracture and the topography of the fractured surface. Fractography is a vast branch of study, whose initial records date back to the 16th century and which evolved into the current Electronic and Quantitative Fractography, which allows relating, for example, the groove marks with the probable loading cycle suffered by the component. In this work, real accident investigated, whose mechanical failure were due to fatigue, will be revisited and evaluated in the light of specific bibliography: from the understanding of the original functioning of the mechanical system, passing through a brief metallography of the collapsed material and then by fractographic analysis and inferences physics and mathematics derived therefrom, to results and conclusions that - it is hoped - add knowledge to professionals who are here in search of good analysis techniques for new - and unfortunate - accidents.