Page:NTSB Report, Japan Air Lines Flight 813.pdf/16

- 13 - 1.15 Tests and Research

Two pieces of the low pressure compressor case, one with an area of rivet holes used in riveting the torque ring in place, and one piece of the fourth stage stator vane assembly, were given laboratory examination. The examination of the two pieces of compressor case showed severe rotational abrasion, and associated high temperature had occurred in the section of the case that normally mates with the low pressure compressor torque ring. No corresponding evidence of abrasion and high tangereture was found on the lugs of the piece of fourth stage stator vane assembly that mate with the slots in the torque ring.

The examination revealed no fragments of metal that could be identified as from the torque ring. It we noted, however, that both the torque ring and the compressor case "C" flange were fabricated from the same material, AMS 6280 steel.

A visual and spectrochemcal examination of samples of all pieces revealed no evidence of rivet material in the abrasion and heat damage areas on the pieces from between the case "C" flange and torque ring. It was noted that the dissimilar metal composition of these components and. the rivets would have made rivet material readily identifiable under spectrochemical examination. The rivet holes in the case piece did. not show any evidence of elongation in the direction of compressor rotation.