ROVworld Subsea Information

SeaBotix LBV ROV recovers black box
Date: Monday, February 16, 2009 @ 13:30:00 EST

SeaBotix LBV ROV recovers black boxIn April of 2008, a Metroliner aircraft carrying mail from Sydney Australia to Brisbane crashed into the ocean about 5NM off the coast. The only person on board, the pilot, was killed in the crash. Since this was the second fatal crash involving this same model of aircraft, The Australian Transport and Safety Bureau (ATSB) was anxious to survey the wreckage and recover the black boxes to determine if there were issues with the Metroliner.

The ATSB contracted a salvage company, Svitzer Salvage, and arranged a 72m DP1 vessel as the operating system. In addition to the salvage crew SeaBotix was contacted to provide the ROV capability. Considering the conditions, location and task the LBV150SE-5 with scanning sonar, tracking system and grabber was chosen.

The approximate location of the wreckage was known based on the air traffic control reports and both locating pingers on the cockpit voice and flight data recorders (black boxes). Nine government officials, three salvage and two ROV personnel were on board in addition to the crew. Onsite the first day the DP1 vessel struggled to hold position as the winds exceeded 20 knots, a 2.5 meters swell and a 2.5 knot current. However, the use of a shot line enabled the LBV to overcome the conditions and descend to the seafloor.

Conditions were equally challenging on the bottom, with high turbidity and no ambient light from the surface. Even at 110m, the currents ranged from 1-1.5 knots. A series of transects were conducted with the LBV using the scanning sonar and tracking system. After approximately 2 hours, the wreckage of the aircraft was located. In searching through the many parts of the destroyed airplane two glimmering stripes were seen in the distance. The reflections from the SeaBotix LBV's ultra bright LEDs turned out to be the cockpit voice recorder's (CVR) reflective strips. Using the three jaw Grabber, the LBV held onto the smashed handle of the CVR. The CVR was brought to the surface by lifting the LBV by its umbilical, which has a 100kg working load. Just as the CVR was leaving the water, however, it fell from the jaws of the grabber straight back down 110m.

The LBV jaws were quickly changed out to the interlocking set that would wrap around the handle keeping it from slipping away. Once the LBV reached the seafloor the CVR was quickly located. It landed with the handle in the mud so the LBV was used to ram the box to a horizontal position. Maneuvering around, the handle was locked onto with the interlocking jaws and again lifted to the surface. This time the CVR did not slip away and was recovered to the deck. With the most important item recovered the search continued for the flight data recorder (FDR). After only a few more hours, it was also located. Using the same technique as the CVR the FDR was recovered to the surface.

Over the next day the wreckage was surveyed and the position of key wreckage was logged. A map was then created that showed the wreckage scattered on the seafloor. When it was decided to end the survey an ATSB official asked that a small piece of the wreckage be recovered. Searching around for an interesting piece led to the recovery of the artificial horizon. Later it was discovered that this was the next most useful item for evaluating the crash.

A report has been published regarding the findings. The investigation discovered that the CVR and FDR were not recording during the flight; all data found was from the previous flight. This has led to further investigation into why the black boxes were not recording.

This article comes from ROVworld Subsea Information

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