Former BBC director-general Greg Dyke has criticised the role played by Lord Patten during its recent troubles.
He told the Culture, Media and Sport Committee the BBC has had "a pretty dismal 12 months".
The corporation has come under fire from critics over a range of subjects including the Jimmy Savile sex abuse scandal and the amount of money given in payoffs to departing executives.
Another former director-general, George Entwistle, was forced to resign after weeks in the job at the height of the Savile scandal which engulfed the corporation in 2012.
Asked if Lord Patten, chairman of the BBC Trust, was doing a good job, Mr Dyke said: "N o, I don't think he's doing a good job because I don't know where he was when the crisis happened.
"L et me take that a bit further: the relationship between a chairman and chief executive is all-important in any organisation, it is the most important relationship probably in the organisation, and I thought at the stage at which George Entwistle was clearly in difficulty he needed significantly more support than he got."
It is not the first time Mr Dyke, who ran the BBC for four years from 2000, has criticised Lord Patten.
In an interview last year, he described the former cabinet minister as a " 'busted flush''.
Lord Patten, who was the last British governor of Hong Kong and whose term at the trust ends next year, has already said he has " no present intention of seeking a second term".
Earlier in the session, Mr Dyke told MPs he had expected the BBC to benefit from the success of the Olympics, which showed "how wrong you can be".
He said: "A series of things coming one after another has led to a pretty dismal 12 months."
Mr Dyke said the Savile sex scandal was not unique to the corporation, adding: "I spent many years working in ITV and I don't think it would have been any different if Savile had been an ITV artist."
Asked about how the BBC should be funded, Mr Dyke told MPs that at "some point in the future" the licence fee could be scrapped and " some form of general taxation" could be used to fund the corporation.
But t he former chairman of the BBC board of governors, Gavyn Davies, who was also giving evidence, said: "There is no doubt the licence fee is a bad tax if you were designing a tax," but added it would be "premature" to discard it.
He also told MPs that the BBC paid "too much attention to ratings".
He said: "I thought that the first day I walked through the door and I thought it more the last day."
Mr Dyke said the governance system of the BBC was "a fudge" that worked initially but had started to show failings over the last few years.
He said: "Y ou saw the disaster over Jimmy Savile, over the appointment of a director-general, and that was because I don't think anybody was quite clear whose responsibility was what."
Another former BBC chairman, Michael Grade, told MPs the corporation was "virtually unmanageable" because it was too big.
He said: "I t's still stuck with its history because it tries to do everything itself."