In the ole ATPL(H) material Hydraulic Lock is described as different to Jack Stall- which if I remember correctly is a hydraulic force overload. Hydraulic Lock as I understood it from the ATPL(H) studies is a failure (design or mechanical) in which the hydraulic pressure gets around the back of the relevant actuator(s) and the controls become hydraulically 'locked'.
Definition of mourn - feel or show sorrow for the death of (someone), typically by following conventions such as the wearing of black clothes Definition of mourn - feel or show sorrow for the death of (someone), typically by following conventions such as the wearing of black clothes dictionary thesaurus
Elegy is the kind of poem that mourns the death of someone or something. Tennyson's In Memoriam mourns the death of his friend Arthur Hallam. Oliver Goldsmith's the Deserted Village is about the demise of a Village.