HILO, Hawai'i — The Federal Aviation Administration is investigating an engine failure last week that forced a Hawaiian Airlines interisland flight to return to Hilo airport for an emergency landing shortly after takeoff.

Hawaiian Airlines spokesman Patrick Dugan said the incident was the second case of engine failure since the Hawaiian Airlines B717 interisland fleet was put into service seven years ago, and said there have been about 250,000 departures during that period.

Kris LaGuire, who was a passenger on Flight 121 to Honolulu Friday, said he heard a loud bang from the back of the plane seconds after takeoff about 9:05 a.m. while the aircraft was still over the trees on the coast of the Big Island.

A member of the flight crew told the passengers that "we heard the sound, too," and said the crew was trying to determine what had happened, LaGuire said.

A pilot later used the intercom to explain to passengers that there had been a malfunction in the left engine, and the plane then returned to the airport, LaGuire said. He said the incident happened just a few minutes after takeoff.

Dugan said the engine problem was discovered about seven minutes after takeoff, and may have been caused by a broken turbine blade.

Dugan said the pilot heard the bang, noticed a high temperature reading in one engine, and shut down the engine as a precaution before returning to Hilo.

The pilot notified emergency crews on the ground, which Dugan said is standard procedure for the airline. He said the plane is still in Hilo, and the airline is shipping a replacement engine to the Big Island. The passengers were placed on other aircraft.

Ian Gregor, spokesman for the FAA, said the incident is under investigation by the agency's Honolulu flight standards district office.

Reach Kevin Dayton at kdayton@honoluluadvertiser.com.