Asiana B763 near Phuket on Jan 23rd 2010, engine shut down in flight

Last Update: September 23, 2012 / 15:03:15 GMT/Zulu time

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Photo of Asiana Airlines HL7514, Boeing 767-300 — Asiana Airlines HL7514, Boeing 767-300 (Photo credit: maarten-sr / Flickr / License: CC by-sa)

Incident Facts

Date of incident
Jan 23, 2010

Classification
Report

Cause
Engine shut down in flight

Airline
Asiana Airlines

Flight number
OZ-748

Departure
Phuket, Thailand

Destination
Seoul, South Korea

Aircraft Registration
HL7514

Aircraft Type
Boeing 767-300

ICAO Type Designator
B763

An Asiana Airlines Boeing 767-300, registration HL7514 performing flight OZ-748 from Phuket (Thailand) to Seoul (South Korea) with 251 passengers and 11 crew, had just reached cruise flight level 370 when the crew decided to shut the left hand engine (CF6) down and returned to Phuket for a safe landing on runway 27 about 75 minutes after departure.

South Korea's ARAIB opened an investigation into the occurrence and released their final report in Korean concluding the probable cause of the incident was:

The captain, observing indications of decreasing engine rotation speed and decreasing fuel flow, concluded the engine had failed and prematurely initiated the engine shut down according to the "engine failure and shut down" checklist. The engine had not been reduced to idle thrust.

The cause of the indications was chafing and resulting damage of wires associated with the channel A of the engine electronic control (EEC). The defect had already shown prior to departure resulting in an "L ENG CONTROL" message requiring the crew to take action according to the quick reference handbook, however action was not taken in a timely manner.

The ARAIB reported that following pushback and start of the right hand engine engine #1 was started however a "L ENG CONTROL" appeared. The first officer (32, CPL, 4,162 hours total, 1,081 hours on type) ran the relevant checklist, the captain (61, ATPL, 13,048 hours total, 10,373 hours on type) determined applying minimum equipment list that the flight could be continued. The indication subsequently disappeared while moving on the ground.

The aircraft subsequently departed Phuket's runway 09 and climbed to FL370 when the captain noticed the airspeed had dropped by about 20-30 knots, the aircraft had lost about 200-300 feet of altitude and the left hand engine's fuel flow indication was substantially below the right hand engine's indication and the left hand engine's N1, N2 and EGT indications were decreasing. The captain thus concluded the left hand engine had failed, initiated the shut down of the engine, declared emergency and decided to return to Phuket where the aircraft landed safely on runway 27 about 75 minutes after departure.

A subsequent inspection of the engine showed no anomaly with the engine, the engine electronic control however failed tests. Readout of the stored parameters and EEC history out of NVRAM indicated that channel B of the EEC had been marked inactive due to an earlier incident, that could no longer be determined, leaving the EEC with just channel A.

Further examination revealed that chafing had occurred on wires connected to the channel A, a short circuit between the left thrust lever position wire and the N2 speed sensor wire resulted from the damage of the wires resulting in false thrust lever position readings as well as fluctuating N2 speed readings by the EEC.

According to the relevant checklists and the engine manufacturer a shut down was not necessary, reducing the engine to idle was the much safer course of action.

The ARAIB analysed that the crew incorrectly applied the minimum equipment list at engine start upon the "L ENG CONTROL" message. The message does not permit continuation of flight.

The ARAIB further analysed that the safety of the flight was compromised when the engine was shut down prematurely and without according instruction by the relevant checklist, that would have commanded the engine reduced to idle thrust.

The ARAIB stated there was no evidence of any fault in the company procedures, maintenance and management of the EEC (editorial note: the report however made no attempt to explain why the EEC's channel B being inoperative has not been detected).