SDLC?
Technical debt in IT? Deferred maintenance and upgrades? For hardware maintenance, the cases need to be popped open for cleaning out the dust and what have you, hard drives need periodic defragging. This is not including replacing parts that fail. Software maintenance includes running backups, applying patches for security and bug fixes. The SDLC for government systems can be measured in decades, and is usually part of waterfall methodology. That's government thinking for you. Mission critical systems, such as the systems that handles the collection of taxes and then doles it out to the different agencies as part of their capital budget, you cannot accrue technical debt in the maintenance of those systems. You might be able to do it for awhile and get away with it, but when something fails, you got the PHB running around with his two tuffs of hair on fire.
At some point, you have to upgrade the hardware. The two most replaced items in the box due to failure (in my experience) are hard drives and power supplies. Other components such as memory do fail, but it's rare. Video cards are another item that fails, but those are seldom. Backup tapes are another thing that needs regular replacement. The budget for failed components should be factored in to the total cost of ownership, but it rarely is. How many of you work or have worked in shops where they maintain an inventory of spare parts? I've worked in a few, but when budget cuts roll down the hill, that's the first victim. When the inventory is depleted, then chaos ensues because a system is dead for several days because the parts are on order, if they are available at all. There was one IT department where the budget was so tight, the management asked the IT folks to buy replacement parts out of their own paychecks and file for reimbursement because it was faster than waiting for official channels.
In corporate America, management types get promoted to their level of incompetence. This is especially true in government. It's good to know that this seems to be the standard everywhere.