How a commuter plane lost a propeller blade above Great Barrier Island at the weekend is the subject of a Transport Accident Investigation Commission inquiry.

The Great Barrier Airlines Trislander - a three-engined aircraft - had to make an emergency landing shortly after taking off from Claris Airport at 11.30am on Sunday.

The drama occurred as the pilot was flying 10 passengers to Auckland in good conditions with 15-knot winds.

Shortly after take-off, the plane lost one of the two blades on the right front propeller over swampy ground.

When the pilot noticed trouble with the engine, he returned to Claris, although airline chief executive Gerard Rea said the plane could have flown "comfortably" on the other two engines.

"The total time in the air was about five or six minutes. [The pilot] just basically turned around and landed."

Passengers wouldn't have been too aware before the return that something was amiss," Mr Rea said. "They're quite a noisy aeroplane anyway - it's like a bus to the Great Barrier."

Passengers were able to leave the island on a later service.

As well as the commission's inquiry, the airline is also undertaking its own investigation.

Mr Rea said the engine would be stripped by an overhaul company, and the propeller would be sent to the United States. The blade had yet to be found. "We need to determine where the fault eventuated."

Mr Rea praised the pilot for his calmness during the flight and the safe landing.

The commission's deputy chief investigator, Ken Mathews, inspected the plane yesterday. "We need to remove some of the components to find out what happened. The [propeller] hub isn't there."

Mr Mathews said whether the plane complied with safety standards was a matter for the investigation.