Los Angeles — In December, a sightseeing helicopter crashed in Kauai, Hawaii, killing all seven people on board. A Federal Aviation Administration whistleblower now says he was prevented from inspecting the aircraft prior to the crash.

Joseph Monfort is a former Army helicopter pilot and FAA employee since 2009. He told Senate investigators his FAA bosses twice denied him travel authorizations to visit the helicopter company, making it next to impossible to perform adequate FAA oversight.

Another chopper crash in Hawaii in April that killed three people is also getting new scrutiny. The whistleblower claims the FAA did not provide adequate oversight that could have prevented the accident. Senator Roger Wicker is demanding the whistleblower's claims be investigated.

"The folks at the top need to look at what's going on. Where there's this much smoke, there's fire," said John Goglia, who served on the National Transportation Safety Board.

These latest allegations come as the Transportation Department's inspector general is poised to find the FAA administered ineffective oversight of Southwest Airlines, who allegedly flew millions of passengers on jets with unconfirmed maintenance records.

The FAA said it takes these new allegations very seriously and will fully cooperate.