This report covers the testing and verification of the plate and shell element library of the Intergraph Finite Element Package, I/FEM and the subsequent use of this package for the modelling and analysis of the reverse duct of a jet unit currently in production by the Jet Division of C.W.F. Hamilton Ltd. The element testing and verification closely followed by the method used MacNeal and Harder and others, which involved testing the finite elements for every possible type of deformation, and then grading the performance of the element as a result of these tests. The element with the highest overall grade, or the best performance in the types of deformation for which the element will be experiencing in the analysis, was selected for use in the following analysis. This analysis has been carried out with the aid of an Intergraph "2020" Workstation, running the Intergraph software products I/EMS, or Intergraph/Engineering Modelling System and I/FEM, or Intergraph/Finite Element Modeller. A plate model of the Model 273 Reverse Duct was constructed from drawings supplied by C.W.F. Hamilton Ltd., and this model was then 'meshed' and after appropriate loads and boundary conditions had been applied, was analysed in I/FEM. The results generated being discussed in the text. A small modification to the plate element model was made at the request of C.W.F. Hamilton Ltd., and the model was re-analyzed, the results discussed in the penultimate chapter. Further directions for research are suggested in the concluding chapter, which may lead to experimental verification of the finite element model, and also to improved solution accuracy by a modification of the finite element model.