The report by the Transportation Department's inspector general's office confirmed many of the allegations brought by a in 2005 and again in 2008 of a cozy relationship between FAA managers and the airlines they are charged with inspecting.
FAA inspector Mark Lund charged that FAA managers at the safety office that oversaw Northwest routinely allowed the airline to avoid penalties or fines by voluntarily disclosing failures.
In response, the FAA headquarters initiated a national review of safety order compliance at major airlines in 2008 that found 14 instances in a four-month period in which Northwest didn't comply with safety orders, one of the highest of all the airlines reviewed, the IG report said.
The failure to comply with FAA safety orders continued even after FAA's review, the report said. There were eight more instances in which Northwest didn't carry out safety orders in the budget year ending on Sept. 30 2009, the report said. The FAA office overseeing the airline closed five of those cases without recommending penalties or fines.
In one of those cases, Northwest had to ground 27 planes because it hadn't inspected landing gear parts as required by a safety order. The inspections were intended to prevent the main landing gear from separating from the wing and possibly rupturing a fuel tank, the report said.
Given that the problems have continued, "the status of Northwest's compliance with more than 1,000 (safety orders) is unknown," the IG report said.
The IG report is dated Dec. 7, 2009. It was released this week by the U.S. Office of Special Counsel, which handles federal whistle-blower complaints.
Northwest merged with Delta Air Lines last year, creating the world's largest airline. It now flies as Delta.
"We are currently reviewing the documents and, as always, we will fully cooperate with the government agencies to ensure our core values of safety, quality and compliance are not compromised," Delta spokesman Anthony Black said.
FAA spokeswoman Laura Brown said the agency "has taken corrective action on the issues identified in the whistleblower complaint and is continuing to monitor compliance."
Linda Goodrich, vice president of Professional Aviation Safety Specialists, the union that represents FAA inspectors, said she is "appalled that an inspector has to go through this much of an extraordinary effort to raise serious safety concerns on behalf of the flying public."
Lund has "taken a lot of abuse" since he went public with his allegations, she said.
The special counsel's office, which is required to report its findings to the president, said in a letter to the White House on Thursday that most of Lund's allegations have largely been substantiated.
Lund has told the special counsel that despite the Northwest-Delta merger, FAA managers are still not backing up inspectors who try to cite the airline for safely problems.
The letter quoted Lund as saying that an inspector "has to typically fight through the FAA management chain" to do his duties and that the FAA's "culture of placing the interests of the carrier over safety continues to pose a risk to the flying public."
The IG said the FAA should conduct another major inspection at Northwest's operations, independent of Delta, and review a sample of past safety orders involving Northwest to better assess its compliance record.
Margaret Gilligan, FAA's associate administrator for aviation safety, said in a December memo, also made public Thursday, that the agency was working to implement the recommendations.