[kach22i]

I heard they were very heavy on maintenance, lot of down time.

Convair B-58 Hustler
https://megaprojects.net/planes/convair-b-58-hustler/




The B-58 Hustler: An Engineering Marvel That Was Nonetheless a Dead End
https://nationalinterest.org/blog/reboot/b-58-hustler-engineering-marvel-was-nonetheless-dead-end-183544

Here's What You Need To Remember: Although an engineering marvel, the Hustler suffered from an appalling accident rate, high maintenance costs, and an obsolete mission profile. It would remain in service for only a decade, a dead-end in strategic bomber development.

Speed Freak
https://www.smithsonianmag.com/air-space-magazine/speed-freak-11315229/

Maintenance crews reported that for every hour the B-58 flew, it took 35 hours of maintenance.