(AP) - An internal audit says the $17.7 million the Tennessee Valley Authority spent on two corporate planes was not justified.

News outlets reported Thursday the TVA Office of the Inspector General has found TVA's reasons for buying an $11.2 million jet and a $6.4 million turboprop did not justify the purchases. The audit says the U.S. government-owned electric utility may have also violated federal code in improper justifications for its aircraft use.

The audit says TVA did not provide documentation of any cost, safety, reliability or time efficiency comparisons before buying the planes.

Mike Skaggs, TVA executive vice president for operations, says say he did not believe TVA was in noncompliance of federal codes, but management has learned from the audit that its flight justification procedure needed to be more detailed.

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