The (mostly) sad story of the NH Industries NH90 helicopter... The first fly-by-wire helicopter and widely used in NATO countries in both naval and utility/transport roles.
https://en.wikipedia.org/wiki/NHIndustries_NH90
The aircraft was conceived as a medium helicopter to replace multiple types such as the UH-1 "Huey" in Army roles, the H-3 Sea King in naval and search and rescue roles, etc. The market was estimated to be large and the project looked to be off to a great start.
Alas, the NH90 has run into problems with many users. Norway, to use the most extreme example, has demanded a refund on its contract for 14 naval variants and has ordered Sikorsky MH-60Rs (as flown by the U.S. Navy) to replace them. The Australian Army bought 47 tactical transports and has recently announced that they will buy Sikorsky UH-60Ms (as flown by the U.S. Amy) to replace them by 2027, but then recently has withdrawn all NH90s from service, leaving a considerable gap. Sweden bought 18 and has announced that they will be replaced with Sikorsky helicopters. Other smaller users are also planning replacements for an aircraft that was to serve for many years.
Germany and Italy are the biggest users -- with well over 100 each --and have not publicly complained, but one suspects they are having problems, too.