Cockpit voice recorder useless
Wednesday, October 20, 2004 Back The Halifax Herald Limited

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The MK Airlines Boeing 747 crash site is seen from the air on Tuesday near the Halifax International Airport.



The end of the runway where an MK Airlines Boeing 747 hit before crashing is seen from the air on Tuesday.



The flight data recorder, still being investigated in Ottawa, lies at the crash site earlier this week.



Investigators sift through debris at the crash site of an MK Airlines Boeing 747.



The MK Airlines 747 crash site near the Halifax International Airport is seen from the air Tuesday. A cockpit voice recorder found at the scene was ruined in the fiery crash, but investigators hope to glean some information from the data flight recorder.



Searchers comb through wreckage at the crash site at the Halifax International Airport.



It may be days before investigators are able to begin to remove the larger sections of wreckage.


Device sustained too much damage, investigators say

By PATRICIA BROOKS / Staff Reporter

No one will ever know what the crew of an MK Airlines Boeing 747 said to each other before last week's fatal crash at the Halifax International Airport.

"We had a significant milestone (Monday) when we recovered the cockpit (voice) recorder, that was the good news," Bill Fowler of the Transportation Safety Board told a Tuesday news conference.

"The not-so-good news is that the recorder was damaged such that there was no retrievable data."

Flight 1602, heading for Spain, careened off the end of Runway 24 and burst into flames Thursday around 4 a.m., killing all seven aboard.

Investigators have a tape of the conservation between the crew and air controllers before the crash, but Mr. Fowler said it likely won't be released.

He said he was unaware of any indication on the recording of a problem on the Ghanaian-registered plane.

Investigators also have the damaged flight data recorder that was retrieved Sunday. It has been repaired and specialists have determined that it recorded 107 pieces of data related to various onboard systems, Mr. Fowler said.

That information still has to be analysed by the safety board's engineering office in Ottawa, which could take up to a couple of weeks.

"If we do get it (the data), it will certainly answer several questions and provide us with some significant information," Mr. Fowler said.

Investigators are also looking at the plane's maintenance and performance. They still don't know why its four engines were recently replaced in Indonesia, but they are especially interested in how the new engines were working at the time of the crash.

They want to know the speed at which they were turning, the amount of thrust produced, the exhaust gas temperature, and how fast the plane was travelling, Mr. Fowler said.

If information on the flight data recorder is unusable, he said investigators are ready to use "traditional methods," including a physical examination of the engines.

"It is much less refined than if you had a recorder."

The plane also had a "quick access recorder" that has not been found, said Mr. Fowler, adding the device is unprotected and would have been at the centre of destruction.

The investigators, including the Canadian safety board, the RCMP, Federal Aviation Administration and National Transportation Safety Board, as well as aviation authorities from Britain and Ghana, are also probing the jet's weight. That's difficult to determine based on physical evidence at the crash site, Mr. Fowler said, but they've started tracing the cargo back to its source to see how much the plane was carrying.

Officials in Hartford, Conn., were trying to get specific cargo information from Bradley International Airport where the plane loaded up before heading to Halifax.

The day of the crash, MK Airlines official Steve Anderson said the plane was almost half full of John Deere lawn tractors and "general freight, which is everything from computers to anything you can imagine."

After it arrived in Halifax, it was also loaded with 53,405 kilograms of silver hake and lobster destined for Spain.

Mr. Anderson has said the cargo weighed 103 tonnes and that the plane could carry 110 tonnes.

Investigators have ruled out nothing, including speculation the cargo may have shifted during takeoff.

The flight data recorder might help determine whether that happened, possibly through a change in acceleration, Mr. Fowler said.

Investigators will also look at the wreckage and inspect the loading and cargo mechanics.

As well, they have studied a videotape of the aircraft turning on to the runway, Mr. Fowler said.

"I can't tell you exactly where the aircraft turned but we're confident that almost all the runway was utilized - they were very close to the end."

Investigators were taking daylight photos at the exact location of the video camera, which "will tell us quite accurately" where the plane started its acceleration.

It may be days before investigators begin removing larger pieces of wreckage from the site because roads need to be built to get heavy equipment in, Mr. Fowler said.

From a helicopter flying 150 metres above the crash site Tuesday, backhoes could be seen digging and spreading gravel for two roads running from the Old Guysborough Road to the doomed plane's fuselage in woods across from the airport.

The path of destruction began past the end of Runway 24, where the aircraft tried to take off.

Investigators say the tail of the jet bounced twice off the tarmac near the end of the runway and separated from the plane when it hit a mound of earth 300 metres beyond the end of the runway.

From the helicopter there were no gouges visible in the pavement, but two tire marks in the brown grass led to a line of orange posts, part of the airport's navigational system.

Two of the posts were on the ground, followed by the tail of the plane with the airline's logo, a red M and a blue K, smaller pieces of debris and another part of the tail.

The debris field ended before the trees at the airport fence that lines Old Guysborough Road. There was nothing visible on the pavement, except for RCMP cruisers blocking access to motorists.

Green military tents, trailers, portable toilets, cars, trucks and vans - the on-site base for investigators - lined a dirt road leading from inside the airport fence to the paved road.

On the opposite side of Old Guysborough Road, the rest of the wreckage stretched out in almost a straight line from the end of the runway.

The charred fuselage was surrounded by scorched trees and bits of metal like burned shreds of paper scattered about.

Beyond the fuselage, amidst the ash-like debris, lay three pieces of metal, two yellow and one bright green, the colours of the famous John Deere tractor company.

Making Sure the Recorders Survive
Things have come a long way since 1958 when it was the state-of-the-art in crash-survivability that had the major influence on the level of the minimum requirements for crash-survivability. Today the minimum standards are set according to the conditions that a flight recorder is likely to meet in a crash.
These days to become certified for use flight recorders must pass a collection of extremely arduous tests. These include:


Fire.

This is two-fold, the flight recorder casings must protect the recording medium from 1100degC (the temperature at which aviation fuel burns) for thirty minutes (simulating the initial fuel fire after a crash). It must then be able to protect the recording medium from a temperature of 260degC for ten hours (this simulates a long baggage-fuelled fire).
Common heat-insulation materials used include polymers, wax and gelled which - all offer good protection from high temperatures.


Water protection and Deep Sea Water Pressure Resistance.

The casing must protect the recording medium for thirty days underwater at a pressure equivalent to being submerged at 20,000ft below the ocean surface.

Static Crush Test.

The recorder must withstand a 5,000-pound pressure applied against all six axis points.

Penetration Resistance.

The recorder must withstand a 500lb force being dropped on it from 10 feet up, the point of contact being a one-quarter inch diameter hardened steel spike.

Impact Test .

In this test the recorder is fired from an air cannon into an aluminium wall. This simulates the required, 3400g deceleration in 6.5 milliseconds (which is equivalent to going from 350 mph to zero in 16 inches).


Fluid Immersion Test .

To check that the recorder will not be eroded by any of the fluids that are most commonly carried by planes, the recorder must survive emersion for 48 hours in each of the following:
hydraulic fluid
lubricating oil
aviation fuel
fire extinguishing agents
and toilet flushing fluid .

 

Sometimes Freighter Crews cut it a bit fine

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