Factors that cause levee failure include overtopping, erosion, structural failures, and levee saturation. However, many problems only occur as a result of multiple failures or errors. These sensors tend to cause intermittent problems due to internal electrical failures. Altimas had major excessive oil consumption issues causing potential catastrophic engine failures. The operation was aborted due to problems with helicopter failures. All of the losses were due to engine failures or effects of turbulence. The rankings focus on presidential achievements, leadership qualities, failures, and faults. His "failures" tended to be successes. A megaproject's economic failures (and successes) have common characteristics. There are many reasons for project failures. See below for floating pontoon failures and disasters. Critical "failures to convey" occurred. Brooks discusses several causes of scheduling failures. The punishments for perceived failures and disloyalty were often exceedingly harsh. Edmund attempts its defence without justifying its failures.