All Nippon Airways Co. and Japan Airlines Corp. will replace parts in engines made by Pratt & Whitney of the United States in their Boeing 777s for about 9.5 billion yen due to incidents involving engine trouble earlier this year, the airlines said Thursday.

ANA will replace blades in the high-pressure turbines of 42 engines for some 5.2 billion yen and JAL will pay about 4.3 billion yen to mend 39 engines.

The two major Japanese airlines have a total of 48 twin-engine Boeing 777s with troublesome Pratt & Whitney engines.

ANA said the turbines' blades deteriorate and get damaged because of bad plating produced in the United States. This caused excess vibration to develop in one of the engines of two of its Boeing 777s during domestic flights, on Sept. 28 and Oct. 29.

The planes were forced to make emergency landings, but no one was injured.

The engine maker has admitted to its errors, ANA said.

JAL said it has detected similar defects in three cases, but they did not cause accidents.

The two major Japanese airlines said they will replace the high-pressure turbine blades in planes using Pratt & Whitney engines produced before December 2003, when the maker improved some of its production processes.