MIA97LA125

Upon arrival in Memphis the aircraft was found to have wrinkling damage to the outboard elevators and elevator counter weights. The flightcrew reported they had no turbulence or other events during the flight that would have caused the damage. Readout of the 25 hours of data contained on the digital flight data recorder (DFDR) did not show any events that would have caused the damage. Examination of the elevators showed no material defects or preexisting damage. The aircraft manufacturer stated they have seen similar damage to elevators caused by stall buffet at high altitude or high speed buffet at high altitude. The aircraft received an 'A' check while on the ground prior to departure for Memphis and no discrepancies with the elevators were noted. The flight engineer reported that he did notice any discrepancies with the elevators during preflight inspection on the flight to Memphis.

On April 9, 1997, about 0016 central daylight time, a McDonnell-Douglas DC10-30F, N310FE, registered to Wilmington Trust Company Trustee, and operated by Federal Express Corporation as Flight 52, a Title 14 CFR Part 121 scheduled domestic cargo flight from San Juan, Puerto Rico, to Memphis, Tennessee, was found to have damage to both elevators on arrival in Memphis. Visual meteorological conditions prevailed for departure from San Juan, and during arrival at Memphis. The aircraft sustained substantial damage and the airline transport-rated pilot, first officer, flight engineer, and three jump seat passengers were not injured. The flight originated from San Juan, on April 8, 1997, about 2121 Atlantic standard time.

The flightcrew stated that the flight from San Juan, to Memphis, was uneventful and that they did not encounter any significant turbulence or any other events that would have stressed the aircraft enough to cause the damage to the elevators. On arrival in Memphis they were notified by ground maintenance personnel that both elevators had damage.

Readout of the digital flight data recorder (DFDR) from N310FE was conducted by the NTSB Flight Data Recorder Laboratory, Washington, D.C. and Federal Express Corporation, Memphis, Tennessee. All 25 hours of data contained in the DFDR was read by NTSB. The data did not contain any events that could be identified as causing the elevator damage. (See NTSB Memorandum).

Examination of the damaged elevators was conducted under the supervision of an FAA Inspector at the Materials and Process Engineering Laboratory, Boeing Commercial Airplane Company, Douglas Products Division, Long Beach, California. Each elevator had wrinkles in the upper and lower skins at the outboard ends. The as-received elevators and outboard hinges were examined for prior cracking, corrosion, and foreign object damage which might have contributed to failure initiation. Nothing significant was found. The lower left hand balance weight skin and the lower left hand outboard elevator skin exhibited more wrinkling than the right hand elevator. A small crack was found in a rib in the left elevator outboard area. The crack had features typical of overload. (See Boeing Report).

Boeing personnel reported that several occurrences of damage to elevators on DC-10 aircraft had been reported by operators and in each case it was determined the aircraft had entered into stall buffet or overspeed buffet. Additionally, during flight testing of the DC-10, damage to elevators was found after stall maneuvers. The damage found on the elevators of N310FE was similar to the damage found in the above cases. (See Boeing Letters).

The aircraft was released by NTSB on April 11, 1997, to John L. Fraley, Senior Flight Safety Analyst, Federal Express Corporation, Memphis, Tennessee. Components retained by NTSB for further examination were released to Federal Express Corporation.