Following last week's crash of a B-17 bomber at Bradley International Airport that killed seven people and injured seven others, U.S. Sen. Richard Blumenthal, D-Conn., is asking the head of the Federal Aviation Administration to look into "what specific inspection protocols" went into allowing passengers to fly aboard the 75-year-old aircraft.

Blumenthal, in his letter, references a March 22, 2018, document from the FAA granting and amending a petition by the Stow, Mass.-based Collings Foundation, which owned and operated the B-17 bomber, to allow the organization to charge passengers for flights on board its aircraft to cover the cost of maintaining and preserving them.

The B-17 was among 10 aircraft owned by Collings that were eligible to fly under the exemption known as "living history flight experiences." Aviation records show the plane was certified to fly by the FAA until November 2022.

"Vintage military aircraft are a profoundly significant part of our history – providing important experiences and learning opportunities for our veterans and military aviation enthusiasts across the country," Blumenthal said in the letter. "However, these planes are many decades old and contain original or rebuilt engines and equipment – requiring inspection and maintenance programs that recognize the significant differences between these planes and more modern civil aircraft."

Seeking to "better understand the conditions and limitations required of Collings to operate these aircraft," Blumenthal sent FAA Administrator Steve Dickson a series of questions, including how the FAA ensures that pilots of these vintage aircraft receive proper training on how to respond to emergency situations such as engine failure. He also asked, referencing reports that the aircraft previously had engine problems, what the FAA's requirements are for reporting such problems.

The FAA's letter to Collings laid out a long list of conditions and limitations associated with the living history flight exemption such as documenting all flight training and testing and reporting any failures or malfunctions of any landing gear system, fuel system, brake system and propeller system.

Minutes after taking off last week, the pilot of the four-engine, propeller-driven plane, Ernest "Mac" McCauley, reported engine trouble. The plane struck approach lights as it turned back to the runway, hit a de-icing facility and burst into flames. McCauley, 75, who died in the crash, has been called one of the most experienced B-17 pilots in the country.

The cause of the crash is under investigation by the National Transportation Safety Board. A preliminary report from the NTSB with its findings is expected soon, but it could take 18 months before the agency completes its investigation. The agency will review whether Collings followed the regulations stipulated under the FAA exemption as part of its investigation.

Since 1982, the NTSB has investigated 21 accidents involving World War II-era bombers, resulting in 23 deaths, the Associated Press reported.

Collings has suspended its flight operations and the Wings of Freedom Tour, through which the foundation brings its vintage aircraft to local airports to allows visitors to view them or take a flight for $450 per person, for the remainder of 2019.

In a statement issued the same day as the crash, the foundation said it "is fully cooperating with officials to determine the cause of the crash of the B-17 Flying Fortress and will comment further when details become known."

j.bergman@theday.com