Panel Confirms Flaws in S. Korean K21 Infantry Vehicle

A team of military and civilian experts concluded that critical flaws in the design of the K21 amphibious infantry fighting vehicle caused back-to-back sinkings of the vehicle in July and last December, Seoul's Ministry of National Defense said Nov. 30.

In a report to South Korea's National Assembly, Defense Minister Kim Tae-young cited lack of buoyancy, malfunctioning of the wave plate and a problem with the drain pump as key factors.

A soldier died when a K21 sank during a river crossing exercise July 29. It was the second time the new vehicle had sunk since it entered service in November 2009 after 10 years of development.


The K21 was developed by the state-funded Agency for Defense Development (ADD) and Doosan DST with an investment of about 90 billion won ($78 million).

"An armored vehicle weighing 25 tons or more is required to maintain at least 20 percent of reserve buoyancy when it crosses the river, but the K2 has been found not to meet that requirement," Kim said, citing the results of a two-month probe of the accidents.

The front of the vehicle, where crew members were on board, became heavier than the rear section, allowing water to flow into the air intake hose of the engine, he said.

The investigation revealed that the spread of the vehicle's weight is unbalanced, with 54.2 percent of the total weight in the front part, said the minister.

The height of the wave plate also is found to be shorter than the requirement, he noted. The plate was required to be 22 centimeters high under the original design requirement, but the manufacturer changed the design in consultations with the Defense Agency for Technology and Quality (DTaQ).

As a result, the plate's height was designed to become 7 to 11 centimeters.

There also was a problem with the drain pump, according to the investigation. When the vehicle moves at full speed, the pressure inside the engine compartment goes down, so more water flows into the compartment. But the pump fails to adequately remove the water.

The design of the vehicle will be modified and improved for tests in February, according to the defense minister.

About 25 officials involved in the K21's development from the ADD, the DTaQ, the Defense Acquisition Program Administration and the Army's test and evaluation group will be held accountable for the problems, he said.

The Defense Ministry also is reviewing ways of holding Doosan responsible for the flaws.

The ministry decided to put on hold the planned deployment of 50 K21s this year and 59 for next year until the problems are fixed. About 900 K21s were planned to be fielded in stages over the next decade.

The vehicle was designed with a 750-horsepower turbo-diesel engine and a 40mm automatic cannon capable of shooting down slow-moving aircraft. It can engage in C4I warfare using digital communications, GPS receivers and inter-vehicle digital links.

The K21 is said to be able to travel as fast as 44 mph on paved roads and to cross a river at a speed of 5 mph with the help of a water jet propulsion system.