NTSB lashes out at FAA on maintenance scrutiny

Aviation International News » April 2004
March 28, 2007, 12:00 PM

The NTSB issued a scathing indictment of the FAA’s oversight of contract maintenance providers, essentially validating a DOT inspector general’s report that again exposed one of the lesser known practices of the U.S. airline industry. The latest report, made public in late February, again pointed to lax FAA scrutiny of a third-party maintenance contractor as one of the main contributors to the January 2003 crash of Air Midwest Flight 5481. Unfortunately for the 21 people who died in the crash, the regulators’ call to action came too late, once again opening them to criticism for what many consider a highly reactionary and politicized approach to safety oversight.

After all, this wasn’t the first time the NTSB found deficiencies in the FAA’s oversight of maintenance contractors. Less than a year ago the Board cited the FAA’s approval of less frequent lubrication of trim-control jackscrew assemblies as a contributor to the crash of an Alaska Airlines MD-83 off the coast of California in 2000 that killed 88. Just two years earlier, a Safety Board investigation into the 1996 crash of a ValuJet DC-9 into the Florida Everglades found that lax FAA oversight of contract maintenance firm Sabre-Tech played a role in that accident.

While such high-profile events often thrust the regulators into action, albeit after the fact, they do so under the constraints of a finite budget–and often in the sort of shortsighted manner too often associated with government bureaucracies. Of course, politics and public relations play huge roles in decisions on the kind of issues that get attention. For example, after a series of crashes of commuter turboprops in the early 1990s, the rule that subjected most formerly Part 135-governed scheduled airlines to comply with Part 121 standards followed in 1997. But when the FAA cannot or will not pay attention to the less visible details that ultimately dictate levels of safety, incidents such as Charlotte occur–and reveal failings already well known by those who toil in repair hangars and fly the airplanes every day.

The NTSB report on the Charlotte crash concluded that the FAA again contributed to the accident by virtue of its “failure to aggressively pursue the serious deficiencies in Air Midwest’s maintenance training program that were previously and consistently identified.” Additionally, the Board said that the agency’s negligence “permitted the practices at the Huntington [W.Va.] maintenance facility during the accident airplane’s maintenance check.”

The NTSB said the quality-assurance inspector at the company hired by Air Midwest to perform repairs on the Beech 1900D–Huntington-based Raytheon Aerospace, now Vertex Aerospace–“did not provide adequate on-the-job training and supervision to the structural modifications and repair technicians mechanic who performed the maintenance on the accident airplane’s elevator control system.”

It also implicated the inspector and mechanic for not following the elevator control system rigging procedure as written. As a result, they skipped a critical step that would have likely detected the misrigging and therefore prevented the accident.

Seconds after Flight 5481 had taken off from Charlotte’s Runway 18R at 8:45 a.m. for a half-hour flight to Greenville-Spartanburg Airport in Greer, S.C, captain Katie Leslie issued an emergency distress call to ATC. By the time she could finish the transmission, the airplane pitched upward from seven degrees nose up to 52 degrees nose up, veered left, turned over and crashed into the corner of a US Airways maintenance hangar, killing all on board.

The airplane’s flight data recorder showed erratic elevator movement during takeoff, as it did during all eight flights since the mechanic at Raytheon Aerospace worked on the airplane just two days earlier. Investigators subsequently found that the mechanic incorrectly rigged the elevator cable, restricting the elevator’s downward travel to about half of the manufacturer’s specifications.

An FAA review of maintenance practices following the second fatal accident involving a Beech 1900 last year–the August 26 crash of a Colgan Air 1900D off the coast of Massachusetts–found that Raytheon service manuals incorrectly illustrated the installation of a key part of the airplane’s elevator trim system. The agency issued an AD on all Beech 1900s, 1900Cs and 1900Ds, effective October 15, which required operators to revise their manuals with a corrected illustration of the elevator trim drum assembly. In the manual, the illustration showed the cable drum at 180 degrees from the proper installed position and erroneously depicted the open, keyed side of the drum rather than the flat side.

Although regulators stopped short of drawing a direct connection between the manual error and either of the accidents, the NTSB has recommended “improved maintenance work card and manual instructions” among a list of 21 safety recommendations. During an NTSB hearing into the Charlotte disaster in May, testimony centered on the clarity of the Beech 1900’s manual instructions. In February last year Air Midwest vice president of technical services Joe Mechalek wrote to the NTSB, explaining that the manual “lacked explicit instructions which, if included, could have avoided the elevator misrigging.”

The NTSB also confirmed the long-held suspicion that weight-and-balance issues contributed to the crash, and faulted the weight-and-balance programs of both Air Midwest and the FAA. Using FAA-approved weight calculations, Air Midwest baggage handlers assumed they loaded the airplane to within 100 pounds of the airplane’s 17,000-pound mtow. However, subsequent findings showed the airplane’s center of gravity at 5.5 percent beyond the aft threshold, indicating an overweight baggage hold.

Workers loaded the maximum number of bags under FAA guidance, which until a recent revision raised estimates to 30 pounds, suggested airlines assume an average weight of 25 pounds per bag for domestic flights, unless the piece weighs more than 50 pounds. Under most operators’ weight-and-balance programs bags weighing between 50 and 70 pounds fall under the “heavy” category, under which airlines assumed a weight of 50 pounds per bag, even though most invariably weigh more than that. Operators must only include the exact weight of a bag in the total if it weighs more than 100 pounds, in which case it falls under rules governing cargo.

The board concluded that the improperly rigged elevator cable and the incorrect weight-and-balance assumptions combined to render the airplane completely uncontrollable. “This accident shows how important it is for everyone involved in the safety chain to do their jobs properly,” said NTSB chairman Ellen Engleman-Conners.  

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