Chicago-based private equity firm GTCR is exploring a sale of <a data-tracker-action="click" data-tracker-category="nav" data-tracker-label="inline_link.01" href="http://www.gtcr.com/investments/technology-media-telecommunications/?=company-camp-systems" target="_blank" title="Link to Website">Camp Systems</a>, which provides aircraft-maintenance tracking software, people with knowledge of the matter said.