HONG KONG, Nov 19 (Reuters) - The Turkish-operated cargo

plane that skidded off the runway at Hong Kong's international

airport last month, killing two airport workers, experienced an

acceleration in one of its four engines after landing, an

initial investigation has found.

A preliminary report from Hong Kong's Air Accident

Investigation Authority (AAIA) released late on Tuesday said the

flight from Dubai, operated by ACT Airlines on behalf of

Emirates, was normal until shortly after landing.

The Boeing 747 cargo plane had been dispatched with

the thrust reverser on engine 4 not working, which was allowable

under aviation rules, the report said.

Thrust reversers redirect the engine thrust forward after

landing to help slow the aircraft.

After the plane, being flown by the first officer,

touched down on the runway, its automatic braking system

disengaged and the captain took control, investigators said.

Shortly afterward, engine 4, on the far right side of

the plane, accelerated to 90% thrust before surging to 106% to

107% over 12 seconds.

Thrust reversers were activated on the other three engines

after the plane veered left off the runway. It struck a security

vehicle, pushing it into the sea and killing the two airport

workers inside.

It was the deadliest airport incident in the financial hub

in more than 25 years.

All four crew on board survived but the plane was destroyed,

with the tail section separating on impact, the report said.

Steven Dominique Cheung, chairman of the Hong Kong

Professional Airline Pilots Association, said it was highly

unusual for a plane to accelerate after landing.

With the right side engine at full power and other engines

trying to slow the plane, there is "no way you can maintain

control," he said.

Boeing ( BA ) referred queries on the preliminary report to AAIA.

Emirates and ACT Airlines did not immediately respond to

requests for comment.

The cause of the crash still needs to be determined by a

full investigation. AAIA said it was collecting further data

including technical issues related to the aircraft's systems,

engineering issues, maintenance records and flight crew

qualifications.

Hong Kong's Transport and Logistics Bureau said on its

Facebook page it aimed to release a final report within a year,

which is in line with international standards.