Follow-up:
JAS has announced that leasing of Pratt & Whitney JT8D-217A/C engines are going better than expected. JAS is planning to return all of its MD-81 and MD-87 back to service by February 7, and return to normal schedule on February 8. In all JAS will cancel total of 596 flights due to MD-81/MD-87 engine problem, and estimated loss due to this incident to be JYE 500 million (US$ 4.7 million).
The engine manufacture Pratt & Whitney said that they have not heard or seen any similar incidents of JT8D-217A/C from any other users. This obviously suggests the possibility of specific maintenance or operation procedure by JAS as a cause. However, at this moment JAS has been following the procedure which was approved by both the manufacture and the government agency (Ministry of Land, Infrastructure and Transport, which oversees commercial aviation in Japan).