[News Today] MYSTERY SURROUNDING LANDING GEAR

[LEAD]
Today marks three days since the tragedy and analysts are exploring some potential causes of the accident. Going back to the time of the accident, the aircraft's landing gear failed to deploy on time. Despite being equipped with multiple backup systems, none of them functioned. The cause is still unknown.

[REPORT]
An aircraft landing gear consists of three pairs of wheels used during takeoff and landing.

They are activated to absorb the force of landing during contact with the runway and lower the speed.

But none of them deployed in the aircraft that crash-landed at Muan Airport.

The initial speculation was a possible a malfunction of the right engine, where sparks could be seen even with the naked eye.

However, even when one of the engines malfunctions, a hydraulic device for deploying the landing gear can still operate using the other engine.

The government has also made it clear that engine defects and landing gear malfunctioning are not correlated.

Yu Kyung-soo / Director of Aviation Safety Policy, Transport Ministry (Dec. 29)
Problems in the engines and the landing gear are usually not correlated.

If the hydraulic device also fails, an accumulator can be used in emergency cases to supply pressure.
But, apparently this also did not work.

When electric signals are not working, a manual device can be used as a last resort to drop the landing gear.

However, this uses gravity to deploy the landing gear and takes about 30 seconds to operate.

Prof. Song Byung-heum / Korea Aerospace University
There was either no time to use the manual device or it was used but the landing gear failed to deploy.

Experts say it's unusual for all three devices to malfunction at once.

The key questions to answer for the investigation in to the crash are whether there was enough time to respond or if another mechanical failure occurred.