Dual engine failure rare, dangerous: Experts
SIA plane loses power to both engines mid-flight, recovers & lands safely
A Singapore Airlines (SIA) flight from Singapore to Shanghai lost power to both engines on Saturday.
Flight SQ836 encountered bad weather at 39,000ft about 3½ hours after departure from Changi Airport.
The twin-engine Airbus A330-300 jet was over international waters close to Hong Kong at the time.
SIA released a statement yesterday saying that both engines experienced a loss of power, but one engine returned to normal operations almost immediately.
Power to the second engine was also later restored.
"The pilots followed operational procedures to restore normal operation of the second engine by putting the aircraft into a controlled descent, before climbing again," the statement said.
There were 182 passengers and 12 crew, including pilots, on the plane.
The flight, which departed Singapore at about 5.30pm, continued to Shanghai and touched down safely at 10.56pm, Singapore time.
Online aviation site The Aviation Herald reported that the aircraft remained on the ground in Shanghai for about four hours, then departed for the return flight SQ825 and arrived in Singapore with a delay of two hours.
Aviation experts told The New Paper that the failure of both engines is a rare occurrence.
"It is more common for just one engine to lose power, but for two, it's very rare," said Dr Anil Padhra, a senior lecturer in aviation studies at Kingston University in London.
"It's fairly dangerous and the plane essentially becomes a glider."
But he added that passengers on the flight would not have noticed, as the descent would have been gradual, based on the time it took for the descent of 13,000ft.
"The pilot would have been able to handle it and the passengers would still be comfortable," he said.
"The most noticeable thing would probably be less cabin noise as the aircraft descended."
Mr Farid Yusof, a lecturer in aviation management and services at Temasek Polytechnic, said there are procedures pilots follow to get the engines working again in such situations.
"It is not about the difficulty to start an engine in-flight, but more of meeting the correct airspeed at whichever altitude that you are flying at before a restart can be initiated," he said.
"(The pilots have to) get the aircraft to glide at the correct airspeed then initiate in-flight start procedures."
Mr Gerry Soejatman, an independent aviation consultant based in Jakarta said there are various ways engines can lose power.
"Dual-engine failure is dangerous and we need to know why it happened," he said.
"It could have been caused by lack of fuel, birds, blocked fuel supply, volcanic ash, severe weather, or other things we don't know or understand yet."
He also noted that two days before the incident with the SIA plane, a twin-engine regional airliner TransAsia Airways suffered a similar experience.
Flight AT72 was near Taipei on May 21 when its left engine failed.
The pilots were able to restart the engine and the plane landed safely at Taipei's Songshan Airport.
An investigation is still under way to determine what caused the engine failure on that flight.
As for SQ836, Dr Padhra said the engine failure would most likely have been caused by frozen fuel.
"There was bad weather and they were at a high altitude, but were able to restart the engine at a lower altitude," he said.
"It could be that ice formed in the fuel choked the fuel pipes and caused engine failure."
According to the SIA statement, the engines were thoroughly inspected and tested upon arrival in Shanghai with no problems detected.
The airline is reviewing the incident with engine maker Rolls-Royce and Airbus, reported The Straits Times Online.
A spokesman for the Air Accident Investigation Bureau of Singapore (AAIB) told The New Paper they were informed of the incident and are investigating.
"As the occurrence happened over international waters, the AAIB will be the authority for investigating this incident," he said.
"The AAIB is in the midst of gathering information and flight data from the operator."