From a number of years back, very good documentary on the severe maintenance and reliability issues the USN was having with their large, three-engine Sikorsky MH-53E Sea Dragon minesweeping helicopters of the Helicopter Minesweeping (HM) squadrons, as well as the USMC CH-53E Super Stallion versions of the same model. Well worth the watch,
View: https://www.youtube.com/watch?v=LvlcLL5JqDc&t=159s
View: https://www.youtube.com/watch?v=LvlcLL5JqDc&t=159s