Airline Pilot Central Forums - 2006 MD-10 Landing Gear Article

Contractor blamed in 2006 FedEx crash : Local News : Memphis Commercial Appeal

Contractor blamed in 2006 FedEx crash

MD-10 landing gear failed due to 'maintenance procedures'

By Bartholomew Sullivan (Contact), Memphis Commercial Appeal
Monday, February 23, 2009
WASHINGTON --- Two and a half years after a FedEx jet crashed and burned at Memphis International Airport, the National Transportation Safety Board determined that its left landing gear failed in part because of "inadequate maintenance procedures" by an outside contractor.

None of the three aboard the MD-10 operating as FedEx Flight 630 was seriously injured in the accident.
But it did not escape the notice of the aviation community that the incident was the sixth such landing gear collapse on a FedEx plane in 10 years. One of those had been a December 2003 right landing gear collapse, also at Memphis.
The accident on the morning of July 28, 2006, resulted in various service alert directives involving inspections for corrosion after it was determined that "fatigue cracking" on an "air filler valve hole" caused the gear to fail. Boeing, acting as a technical consultant on the investigation, concurred in the findings.
FedEx spokesman Maury Lane released a statement Friday night. "We have worked with the NTSB during the investigation of this incident, understand the findings and our contractors' procedures have been revised to ensure that this over-spraying does not occur again."
NTSB investigator Bill English said the nipple-like threaded hole in the heavy steel landing gear cylinder is used to fill it periodically with nitrogen to absorb the shock of landing. It would always be the weakest spot on the smooth steel cylinder and the misapplication of a fingernail-thick sheeting of nickel made it weaker.
In order to determine the cause, the NTSB fitted another FedEx MD-10 with strain gauges that measured the stresses of landing. Metallurgists analyzed the way a tiny crack can turn into a catastrophic failure.
According to Federal Aviation Administration records, the plane was manufactured in 1975. Much of the 11-page NTSB finding is highly technical and involves metal fatigue. It appears that the MD-10 was converted from a DC-10 in May 2002. Other NTSB records indicate its landing gear had been overhauled by a California firm in April 1997. During the overhaul, nickel plating was applied to the outer cylinder.
The flight originated in Seattle and, by the time it reached Memphis, weighed an estimated 284,069 pounds, including 43,595 pounds of cargo. FedEx documented to the agency it was well within its maximum landing weight of 374,500 pounds.
Tim Grizzle, a former Douglas Aircraft quality assurance inspector, speculated about damage done to the useful life of FedEx landing gears in an article in Air Safety Week a month after the 2006 crash at Memphis. He looked at accidents back to May 1996 and suggested that, if the planes are "required to tanker fuel," they are "probably operating consistently within 90 percent of their max all-up-weight. Each landing in an overweight condition reduces the useful life of items."
He recommended more stringent and more frequent inspection of landing gear components.
In its comments to the NTSB, the Air Line Pilots Association noted that stray nickel plating was found on the landing gear filler valve in the 2003 Memphis crash that was attributed largely to a hard landing. It urged the NTSB to amend its earlier finding that the nickel was not a contributing factor in that failure.
A transcript of the last seconds of the flight shows the cool professionalism of Capt. Jayne C. Akin, then 57, of Counce, Tenn., and first officer Andrew D. Macha, then 38, of Seattle as they struggled to keep the plane on the runway. As the plane landed, the cockpit voice recorder picked up first a "sound of clunk," then the "sound of louder clunk," then the "sound of increasing banging."

-- Bartholomew Sullivan: (202) 408-2726