I've seen similar 'audits' too (though not in the Airline field) - the now defunct 'Accounting firm' Arthur Anderson used to do those kinds of audits* all the time
But wouldnt Delta's be different?
Can anybody find any paperwork from Delta's interaction with a similar job done with Korean airlines?
*
Arthur Andersen LLP, based in Chicago, was once one of the "Big Five" accounting firms among PricewaterhouseCoopers, Deloitte Touche Tohmatsu, Ernst & Young and KPMG, providing auditing, tax, and consulting services to large corporations. In 2002, the firm voluntarily surrendered its licenses to practice as Certified Public Accountants in the United States after being found guilty of criminal charges relating to the firm's handling of the auditing of Enron, the energy corporation, resulting in the loss of 85,000 jobs. Although the verdict was subsequently overturned by the Supreme Court of the United States, it has not returned as a viable business.