In their desire to rescue as many citizens as possible off the rooftops in and around New Orleans, rescuers unknowingly put citizens at greater risk by simply using the CH-47 Chinook helicopters. Due to the downwash created by the Chinook’s twin rotors, these helicopters had to be removed from conducting rescue missions. Instead the CH-47 Chinooks were reassigned to conduct missions such as transporting survivors, food, medical support and sandbags to repair levees. In this capacity, the CH-47 Chinook performed well, but the downwash made them dangerous in direct rescue missions[.]
Meanwhile, moderate (on some issues anyway) Republican Senator John McCain had this to say about the choice:
It is my understanding that the HH-47 was awarded the contract largely on the basis of its advantage over the US101 and S92 in range and payload. That is to utterly miss the point of combat rescue. First, unrefueled range is a non-issue in the age of helicopter air-to-air refueling.
Second, above and beyond the ability to carry a basic crew, defensive armament, limited armor protection, and a reasonable number of survivors—which all three contenders can do—payload is not a critical issue for a CSAR helicopter and never has been. The HH-47's advantage in payload is a direct reflection of its size, and size is a liability not an advantage.
The Chinook also isn't very agile as a result of its size. Here is what I said about the Chinook at dkospedia:
The CH-47 Chinook, introduced in 1961, is the Army's tandem rotor heavy lift helicopter. It carries up to 44 troops (an Army platoon) or about 19,000 pounds of cargo. It has a speed of 136 miles per hour and a range of about 300 miles.
The current helicopter used for the purpose, the HH-60, has an 11 passenger capacity.
Since the CSAR-X is an Air Force program, the job basically often involves rescues in cases of downed aircraft, not stranded Army units.
While the Air Force may have made the right choice, the arguments made on a bipartisan basis against its choice sound very thoughtful and appropriate to me, so the Air Force certainly has some explaining to do beyond what it has offered so far.