NTSB Identification: MIA00IA191.
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Incident occurred Tuesday, June 27, 2000 in FORT LAUDERDALE, FL
Probable Cause Approval Date: 10/23/2001
Aircraft: Dassault F2TH FALCON, registration: XATDU
Injuries: 2 Uninjured.
NTSB investigators used data provided by various sources and may not have traveled in support of this investigation to prepare this aircraft incident report.
The captain stated that the copilot was flying the aircraft, and after rotation, as they were climbing through about 150 to 200 feet, there was the sound of a loud bang, and they felt extreme vibrations. The captain stated that the No. 2 engine gages went to zero, and there was no indication of fire. He further stated that the copilot continued flying the aircraft, and stayed in the pattern, returning for an otherwise uneventful landing. Postincident examination of the airplane revealed that a 2 to 3-foot section of the right engine nacelle, from approximately the 9:00 to the 6:00 o'clock positions, had torn outward, in line with the high-pressure turbine (HPT) area of the engine. Macroscopic examinations, as well as microscopic examinations of the No. 2 engine and recovered portions were conducted, and the examinations revealed a 360-degree circumferential groove on the aft face of the disk, just outboard of the aft 4-tooth knife-edge steel flange. The groove in the disk was consistent with the disk having been in contact with the 1st-stage low-pressure turbine support/nozzle assembly inner casting forward static seal. In addition, rivet holes on the forward static seal, and on the forward flange revealed the presence of fretting marks, which were inconsistent with those of a tightly mated assembly. Instead, the fretting was indicative of an assembly that allowed relative motion between the surfaces. Furthermore, an examination using a scanning electron microscope on the available rivet heads and rivet shanks revealed that one of the rivet shanks showed indications of fatigue, and that the fatigue originated from at least two areas on the outer diameter surface of the shank, and was indicative of high cycle fatigue. There were also heavy fretting underneath the heads of the rivets on the surface that mated with the seal, and the fretting was similar to that found on the front face of the seal, The fretting was consistent with there being insufficient clamping preload on the rivets.
The National Transportation Safety Board determines the probable cause(s) of this incident to be: the fatigue failure of the rivets used to secure the inner casting forward static seal to the 1st-stage low-pressure turbine support/nozzle assembly. The failure of the rivets allowed the forward static seal to machine a groove into the 2nd-stage high-pressure turbine disk to a depth that the disk could not withstand the operating loads, eventually leading to a disk burst and a high pressure turbine failure. Full narrative available
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