MIA97IA206

Postflight examination of the landing gear revealed the right main landing gear cylinder assembly had failed. Examination of the cylinder revealed the cylinder failed due to stress corrosion cracking.

On July 4, 1997, at about 2155 eastern daylight time, a McDonnell Douglas DC-8-61, N27UA, registered to Argo Air Associates, operated by Fine Airlines, as a Title 14 CFR Part 121 nonscheduled international cargo flight, found a cracked right main landing cylinder assembly after landing at Miami International Airport, Miami, Florida. Visual meteorological conditions prevailed and an IFR flight plan was filed. The airline transport-rated pilot-in-command, first officer, and flight engineer reported no injuries. The flight originated from Santo Domingo, about 3 hours 10 minutes before the accident.

Review of maintenance records revealed the airplane was 25,699 pounds below landing weight. The right main landing gear shock strut assembly had accumulated a total of 20, 874 hours.

The right main landing gear cylinder was transported to the Boeing Douglas Products Division for further examination. According to Boeing Douglas Product Division, the failure of the main landing gear cylinder occurred by stress corrosion cracking which initiated at the threaded portion of the lower end along the first and second full, upper, internal thread roots, about 0.85 inches from the bottom of the cylinder. The cadmium plating in the corrosion areas was sacrificially depleted. This depletion of cadmium plating made the base metal susceptible to stress corrosion cracking. No material or processing discrepancies were found. For additional information see Materials and Processing Engineering Laboratory Report No. LR-15773.

Mr. Richard McCallman, Chief Inspector, Fine Airlines, Inc., authorized the right main landing gear cylinder to be disposed of locally by Boeing Douglas Products Division, on December 10, 1997.