19960129004119I

Narrative: aircraft maintenance log book item number 1 engine failed on takeoff roll at 50 knots or less abort accomplished. Fire bottle emptied into number 1 engine. The preliminary investigation of the failed pratt and whitney engine a JT8D-15 serial number 700702 revealed what appears to be a 4th stage turbine problem. The following is a description of what was seen on a visual inspection: when the failure happened the debris that exited the engine punctured the upper portion of the engine exhaust case, the engine fan air duct, the upper power cowl and two holes were made in the vertical stabilizer fin left-hand side. The inlet nose cowl was also damaged during the event. Areas of engine damage; (1) the 4th stage turbine was heavily damaged which ranged from the blade root to the blade tip with many sections of blades missing. One of the blades was missing entirely this included the fir tree section and its securing pin. Viewing the disk with a mirror the missing blade's fir tree cavity showed no damage, the disk was cracked at the apex of the blade cavity and the crack was separated about a 1/4". The 4th stage guide vanes in this area were heavily damaged. (2) the engine exhaust case had two holes in the 1200 o'clock to 230 position unable to get a dimension due limited access. The inner skin surface had many holes that did not exit through the outer skin. The exhaust case struts at the 3,6, and 9 o'clock position were cracked at the inner aft edge adjacent to the exhaust cone. (3) the engine sound suppresser had impact damage in several places and the shroud was cracked. The reverser sleeve also had impact damage and had oil puddled at the 6 o'clock position. (4) the upper power cowl had a hole 1 1/2" long by 3/8" wide and another triangular hole 2 3/4" by 2 5/8". The holes were approx. 10" from the cowling aft edge in the 1200 o'clock to 230 position also there was a slit in the same plane 5/8" long. (5) the inlet nose cowl had one continuous crack running from the 10 o'clock position to the 2 o'clock position where it mounts to the inlet guide vane case. Of the 20 bolts that hold the inlet cowl in place only 5 showed no visual signs of cracks around the mounting holes. (6) a 1/2" from the aft engine mount ring there is one hole 1 1/4" by a 4 5/8" in the fan air duct. Vertical fin damage: one hole with a 1" diameter just above stringer S3 had a piece of turbine blade in it 1" wide by 1 3/4" long. A large gash was found just above the stabilizer front spar. All damage was on the left-hand side and was repaired per srm. The engine has since been replaced and the aircraft is back in service. No related history this engine. The NTSB is now investigating this incident under the number NYC96SA057.