Q: This task is about reading the given passage and construct a question about the information present in the passage. Construct a question in such a way that (i) it is unambiguous, (ii) it is answerable from the passage, (iii) its answer is unique (iv) its answer is a continuous text span from the paragraph. Avoid creating questions that (i) can be answered correctly without actually understanding the paragraph and (ii) uses same words or phrases given in the passage.
In 2007, two FAA whistleblowers, inspectors Charalambe "Bobby" Boutris and Douglas E. Peters, alleged that Boutris said he attempted to ground Southwest after finding cracks in the fuselage, but was prevented by supervisors he said were friendly with the airline. This was validated by a report by the Department of Transportation which found FAA managers had allowed Southwest Airlines to fly 46 airplanes in 2006 and 2007 that were overdue for safety inspections, ignoring concerns raised by inspectors. Audits of other airlines resulted in two airlines grounding hundreds of planes, causing thousands of flight cancellations. The House Transportation and Infrastructure Committee held hearings in April 2008. Jim Oberstar, former chairman of the committee said its investigation uncovered a pattern of regulatory abuse and widespread regulatory lapses, allowing 117 aircraft to be operated commercially although not in compliance with FAA safety rules. Oberstar said there was a "culture of coziness" between senior FAA officials and the airlines and "a systematic breakdown" in the FAA's culture that resulted in "malfeasance, bordering on corruption." In 2008 the FAA proposed to fine Southwest $10.2 million for failing to inspect older planes for cracks, and in 2009 Southwest and the FAA agreed that Southwest would pay a $7.5 million penalty and would adopt new safety procedures, with the fine doubling if Southwest failed to follow through.
A:
When did two whisleblowers allege that Boutris  attempted to ground Southwest Airlines?