Qantas flight suffers mechanical problems

SYDNEY - Another Qantas plane has suffered mechanical problems, leaving several hundred people stranded in Bangkok.

The airline says a Boeing 747 flying from Bangkok to London on Tuesday morning experienced a surge in one of its four engines shortly after take-off at 1am local time.

The captain shut down the engine and flew back to Bangkok airport, landing at approximately 2.30am local time.

"There was no safety issue at any stage," Qantas said in a statement on Tuesday.

"Boeing 747 aircraft can fly normally on three engines.

"Engine surges do not occur regularly, but are not an unknown event on jet aircraft. Qantas pilots are trained to handle them if they occur."

A replacement aircraft is being flown to Bangkok from Sydney and the 335 passengers on board have been taken to hotels.

They are expected to leave for London at 6.50pm local time.

The aircraft last underwent a maintenance check in Melbourne last month.

It's the latest in a series of mechanical problems for Qantas.

Passengers on a flight from Los Angeles to Brisbane were delayed more than 17 hours after engine problems were discovered on the aircraft as it was due to take off on Monday.

They were taken to hotels while a second aircraft was brought in, and finally arrived in Brisbane late last night.

Also on Monday, a Qantas plane flying to Los Angeles was grounded in Melbourne after cracks started to appear in its cockpit window.

On Friday, an engine fault grounded a flight out of Brisbane.

On Wednesday, a Qantas A380 superjumbo suffered two tyre blowouts on landing in Sydney, due to a problem with its brakes.

And on Tuesday of last week, an engine surge forced a Singapore-bound flight to return to Sydney Airport.

Meanwhile, Singapore police are questioning a man who threatened to bring down a Qantas flight from Sydney.

The ABC reported that the apparently delusional middle-aged man was restrained by flight attendants after threatening to disrupt the flight through "mind power".

- AAP