Publication: Cape Argus Issued: Date: 2008-01-26 Reporter:

Army Blames Gun's Maker for Lohatla

 

Publication 

Cape Argus
Date

2008-01-26

Web Link

www.capeargus.co.za

 

An undetected mechanical failure - which the manufactures of an anti-aircraft gun allegedly kept secret - led to the deaths of nine South African soldiers, according to Defence Minister Mosiuoa Lekota.

The nine soldiers, who were stationed with 10 Anti-Aircraft Regiment in Kimberly, were killed in October while taking part in Exercise Seboka at the SANDF's combat training centre in Lohatla in the Northern Cape. Fifteen other soldiers were injured.

The troops were manning and firing a Swiss/German Oerlikon 35mm MK5 anti-aircraft twin-barrelled gun when it went awry.

Speaking at a press briefing in Pretoria yesterday, Lekota said it was the second such incident to occur with the same type of gun.

He would not say where the other accident had happened.

The SANDF has 48 such guns, manufactured by Oerlikon Contraves AG (OCAG) in Switzerland.

According to the Department of Defence's board of inquiry, the gun malfunctioned because a spring pin, which is the size of a matchstick, sheared.

This caused the interface between the hand/motor actuator selector lever and the traverse gearbox to break during engagement.

This led to the disengagement of the control mechanism, rendering the gun uncontrollable during firing. *1

The spring pin is a connector pin in a selection mechanism that switches between manual and electronic control.

The board also revealed that the spring pins in 10 of the SANDF's 48 MK5 guns were also sheared.

Lekota said the manufacturers, which he declined to identify at the press conference, failed to notify the South African government that a pin failure had occurred on a MK5 anti-aircraft gun in another country.

They did not communicate maintenance tasks to prevent the pin failure from occurring or to correct the failure once it had occurred, and did not inform the government about any hardware changes to safety or user drills in South Africa, he said.

Lekota said the guns had been decommissioned now and were undergoing technical inspections to confirm the full scope of the defects.

He said the board recommended that the weapon system be redesigned to ensure safer handling and be subjected to an operational test. It also recommended that an updated product management intervention be conducted.

He said the Department of Defence was talking with its legal advisers on what action could be taken against the manufacturers.

Asked whether the relationship between OCAG and the SANDF would be terminated given the "failure in communication", Lekota said if there was a "reasonable explanation and we are satisfied by the manner of the resolution of the matter, then we will continue to do business, especially if the equipment is the best on the market *2".

Lekota said the SANDF serviced and maintained its equipment regularly.

Helmod-Romer Heitman, Jane's Defence Weekly analyst, questioned Lekota's announcement, saying: "It would be unusual for such a reputable defence company not to send out warnings.

"It is more than possible that warnings were sent *3, but were 'lost' in an administrative shuffle.

"This would not be the first time that this has happened in the defence force," he said, citing examples of technical updates being filed, but not implemented.

He said while the report may answer the questions of what went wrong, the summary did not and left more questions than answers.

"I am bothered by the fact that it didn't say why the gun traversed so far, killing so many people. In training purposes, large steel pins called dead stops prevent the guns from traversing beyond a certain arc.

"The question that now arises is whether the dead stops were in place. And if not, why not? And if they were, why didn't they stop the gun from traversing so far?

"This report's summary gives a reason for the failure, but it doesn't say why it led to the disaster," he said.

Retired Brigadier-General John Delmonte, a former SANDF air defence specialist, also wondered why the manufacturer would fail to communicate any defects.

"It is unusual and alarming if it is the case and even more so if the warnings were filed because of an administrative glitch," he said.

"There may be other issues of safety that need to be questioned".

OCAG spokesperson Irene Stockli said the company would comment on the allegations on Monday.

* This article was originally published on page 3 of The Pretoria News on January 26, 2008

With acknowledgements to Cape Argus.


*1      Either this explanation is simplistic, incomplete or wrong as it just does not make engineering sense.

If a connecting pin broke the system would be designed to fail to safe, not into an uncontrollable state of continuous fire.

In this case the connector pin engages either manual mode or automatic mode, so it should fail to manual mode. In manual mode an operator needs to engage either a firing trigger or a firing pedal to actuate gun firing, but this was not case. So the logic is that the system failed to automatic mode which means that the fire control system must have been emitting a fire control signal. Either this is untrue, thereby negating the previous logic or there is some serious fault in either the design or condition of the fire control system.

But simply stated, a change from manual mode to automatic mode should not, indeed could not, cause gun firing.


If this is indeed the case, then Oerlikon-Contraves would be guilty of negligent system design, but as the top manufacturer of this type of gun I simply doubt that this is the case. Oerlikon have made and sold literally thousands of these GDF-005 and previous variants.


There is something very fishy in the official explanation.


Two other factors are reason for such explanation being implausible.

Firstly, if there were another 9 or 10 guns with sheared pins, then these would also have started firing randomly or uncontrollably at some or other time.

Secondly, this explanation does not accord with reported initial eyewitness accounts of the incident. This involved an initial stoppage which was cleared by the armourers ("Tiffies"). A little later there was another stoppage with a live round being jammed in the breach block. This occurs quite often. This time a gun operator tried to clear the round using (presumably) standard drill. When he (or was it a she?) could not do so, a woman artillery officer ran forward to the gun try to assist (presumably her own gun crew). Then the round exploded in the breach and caused a runaway resulting in the gun barrel slewing around 90 degrees to the left in azimuth and clearly some 45 degrees in elevation. This caused it to fire some 5 to 10 rounds at the downstream gun sites.

The latter account converges entirely with the fact that the gun has a known mechanical failure mode resulting from the intrinsic design of its gas-operated firing mechanism. This causes the gun to fire the round in the breach plus the next clip of five rounds.

While this failure mode is known it is occasional and in reality allows a more reliable gun in battle (for which it was designed). In battle anti-aircraft guns are nearly always pointing upwards and other guns are seldom lined up in a new row 20 metres apart.

That it why on a firing range, whether it be a practice range or a training range, the traversing mechanism includes end-stops placed typically at 30 degrees on either side of the gun's forward position. If a gun slews horizontally out of control and reaches an end-stop, electrical and other power is physically removed from the gun drive. This would cause a spurious burst of fire to be direct forward and away from neighbouring gun sites and other observers.

In this incident and its summarised investigation report by the MoD there is :
There is something very fishy in the official explanation.


*2      It is also now some 20 years old.


*3      The SA Army claims to own 48 GDF-005 models of this gun, which it acquired in 1991. But it also has purchased some 100 GDF-002 models some of which were later upgraded to 005 status.

But the case in point is that these guns were purchased during the arms-embargo era and Oerlikon-Contraves may not even have initially and officially know the destination of the guns (at least some of them). They would probably be disinclined to send out FRACAS (failure and corrective action) Reports to unofficial and possibly even illegal recipients of the guns.


To me it looks like two things :