UPDATE 5-American says TPG could invest in struggling JAL

* TPG may join American in investment in JAL-AMR CFO

* State bank to offer $1.1 bln credit line-sources

* 3 private banks to offer Y25 bln in loans to JAL - sources

* JAL may post 90 bln yen first-half operating loss - Nikkei

* Shares rise 4.8 pct in flat mkt; down almost 50 pct in 2009 (Adds detail on American estimate in paragraph 11)

By Nathan Layne and Nobuhiro Kubo

TOKYO, Nov 11 (Reuters) - Private equity firm TPG could partner with American Airlines on a minority investment in Japan Airlines (9205.T) to prevent its defection to a rival airline group, the chief financial officer of American parent AMR Corp (AMR.N) said.

The emergence of TPG [TPG.UL] as a potential investor comes as the loss-making Japan Airlines seeks its fourth state bailout since 2001, saddled with $15 billion in debt, a massive pension deficit and dozens of unprofitable routes.

The Japanese government pledged on Tuesday to enlist a state bank to offer bridge loans to prevent the airline from running short of cash and said it may introduce legislation to cut a pension shortfall that hit $3.7 billion in March. [ID:nT287070]