TSA failed to detect 75 percent of bomb parts at LAX and 60 percent at O'Hare.
The plane made a diversion to Burgas airport after a passenger reported explosives on board.
The Transportation Security Administration says the airport officer followed correct procedure when screening the singer.
The news comes a week after an internal TSA investigation found major holes in security at America's busiest airports.
While TSA agents hunt for liquids and knives, they are failing to find explosives and guns.
Homeland Security Secretary Jeh Johnson has ordered the acting administrator's reassignment.
An internal Homeland Security investigation shows widespread failures by TSA agents.
A terminal building was evacuated and flights diverted at the UK's sixth busiest airport