A GERMAN expert testifying at the Helios trial yesterday said the pressurisation control systems aboard the ill-fated airliner were in good working order, thwarting a bid by the defence to demonstrate equipment flaws.
Manfred Pasing, Quality Assurance Manager with Nord-Micro – a leading manufacturer and supplier of cabin pressure control systems (CPCS) for large commercial aircraft – said data retrieved from the plane’s cabin pressure controller indicated the outflow valve was in the manual position.
Pasing said data retrieved from a computer chip known as Non-Volatile Memory showed that the plane’s aft pressurisation outflow valve was open at the moment of the crash, confirming the findings of the accident report. Non-volatile memory is computer memory that can retain the stored information even when not powered.
The crash report found that the aft outflow valve was set at a 14-degree angle from the manual position, allowing for partial pressurisation.
It should have been set on auto before takeoff.
Cross-examining the witness, Helios defence lawyer George Papaioannou told the court that the defence team possessed photographs from the crash site showing that the outflow valve was actually shut, or on the automatic setting. The expert said he could not explain this, if it were true.
All exhaust air is dumped to the atmosphere via a valve, usually at the rear of the fuselage. This valve controls the cabin pressure and also acts as a safety relief. In the event that the automatic pressure controllers fail, the pilot can manually control the cabin pressure valve, according to the backup emergency procedure checklist. The automatic controller normally maintains the proper cabin pressure altitude by constantly adjusting the outflow valve position, so that the cabin pressure is as near to sea level pressure.
Responding to another question, the expert said the cabin pressure controller was found to be working well after being salvaged from the debris of the Boeing 737-300.
Papaioannou next asked the witness whether Nord-Micro would be liable in the hypothetical event the outflow valve was on automatic at the time of the crash. Pasing said the company would not be liable since it builds the equipment according to specifications given by the aircraft manufacturer, in this case Boeing.
Pasing said also that, as far as equipment was concerned, the aircraft was operating with the minimum requirement list as specified by manufacturers Boeing. While this was not illegal, the expert added, the cabin pressure controller had been due for a maintenance check as it was close to recording 60,000 hours of flight time.
The defendants in the trial – Andreas Drakos, chairman of the board of Helios, Demetris Pantazis, chief executive officer, Ianko Stoimenov, (former) chief pilot, Giorgos Kikidis, operations manager; and Helios Airways as a legal entity – face 1,190 charges – 238 each – of manslaughter and causing the death of 121 people through a reckless act.
Manslaughter carries a maximum penalty of life imprisonment. They have all pleaded not guilty. The trial continues.
