The Federal Communications Commission is investigating why an Alabama television station went dark during a Feb. 24 broadcast of a "60 Minutes" installment.

The blackout occurred on WHNT-TV in Huntsville, Ala., during a segment on imprisoned former Gov. Don Siegelman that suggested he was the victim of a Republican conspiracy. The station blamed the outage on equipment failure.

Republican FCC Chairman Kevin Martin said Tuesday that the agency had received "some 20-odd complaints" regarding the broadcast and has asked its staff to send a letter asking for an explanation of the incident. A "letter of inquiry" is routine when reviewing complaints against a station and is the first step in an investigation of a broadcast licensee.

WHNT general manager Stan Pylant has said the problem was caused by a malfunctioning receiver.

The station aired the tail end of the roughly 13-minute segment once the signal was restored, and it showed the story again in its entirety during a newscast later that day and again the following day.

Siegelman, a Democrat who was Alabama governor from 1999 to 2003, was convicted of bribery and obstruction of obstruction of justice charges in 2006. Federal prosecutors had accused Siegelman of naming HealthSouth CEO Richard Scrushy to a hospital regulatory board in exchange for $500,000 in donations to Siegelman's 1999 campaign for a state lottery.

The "60 Minutes" story suggested Republican politics was behind Siegelman's prosecution and imprisonment, a claim prosecutors deny.

Democratic FCC commissioner Michael Copps on Monday said he had asked the chairman to send a letter of inquiry to the station.

The FCC could consider the results of the investigation when it renews the station's license, but Martin warned against jumping to conclusions.

"I don't think is fair to speculate about what might or might not have occurred," he said. "We do have some complaints but we've also asked the broadcaster to respond to this."