DATE=11/12/1999 TYPE=CORRESPONDENT REPORT TITLE=EGYPTAIR-POSSIBLE CAUSES-UPDATE (L) NUMBER=2-256118 BYLINE=NICK SIMEONE DATELINE=WASHINGTON CONTENT= VOICED AT: INTRO: Better weather off the coast of Massachusetts is allowing the U-S Navy to resume the search for the cockpit voice recorder from the crash of Egyptair flight 990. Earlier this week, the plane's flight data recorder was pulled from the wreckage off the ocean floor. But Federal investigators say the information it contains failed to solve the mystery about what caused the Boeing 767 to plunge into the Atlantic on a flight from New York to Cairo, killing all 217 people on board. Correspondent Nick Simeone brings us up to date on where the investigation stands. TEXT: Nearly two weeks after the crash, nothing investigators have found explains why flight 990 lost altitude at 33-thousand feet. Egyptair pilots radioed no distress call to ground controllers and the bits of wreckage recovered so far point to no sign of sabotage. The National Transportation Safety Board has now reviewed most of the flight's cockpit data recorder. It indicates the plane's two engines appeared to lose oil pressure and then shut down. N-T-S-B Chairman Jim Hall says the cockpit instrument panel also lit up with a warning to the crew of a potentially major problem with the aircraft. /// HALL ACT /// We, at this point in the investigation of course are not ruling in or ruling out anything until we continue the final analysis of the flight data recorder information and hopefully are able to compare that with the information we get off the cockpit voice recorder. /// END ACT /// What is known at this stage is that for some reason, the flight's autopilot was disconnected after the plane reached cruising altitude, and the aircraft then appeared to make a controlled descent. Learning why the autopilot was switched off could go a long way toward finding the cause of the crash. Jim McKenna is transport and safety editor at Aviation Week Magazine. /// MCKENNA ACT /// With the autopilot disconnected, the two options would seem to be some kind of system failure for which they have no indication yet or an intentional effort by the pilots to descend by pushing the control column forward. Then the question becomes, why would the pilots have done that on what seems to be an otherwise perfectly functioning airplane? And this is why it makes it all the more critical now that the investigators recover the cockpit voice recorder and that it be functioning properly throughout the remainder of that flight so that they can hear the pilots' conversations and the background noises in the cockpit to get a better understanding of why. /// END ACT /// Aviation experts speculate that something may have happened on board the plane to cause the pilot to reduce altitude, perhaps in response to a sudden drop in cabin pressure. What members of the cockpit crew said to each other during the final moments of the flight could tell investigators much about whether the crash of flight 990 was caused by mechanical failure, pilot error or an act of sabotage. /// MCKENNA ACT /// It's certainly possible that there could have been something that caused the cabin decompression, either a structural failure or the detonation of a bomb someplace on the airplane that punched a hole in the side of the aircraft. But again, we're left with N-T-S-B Chairman Jim Hall's comments of the other day in which he said the flight appeared to be normal up until the point that the autopilot disconnected. /// END ACT /// If the flight's voice recorder is recovered in good condition, investigators could have answer to these questions within hours. If not, the search for what caused the crash of EgyptAir flight 990 could go on for months, if not years. (SIGNED) NEB/NJS/JP 12-Nov-1999 18:25 PM EDT (12-Nov-1999 2325 UTC) NNNN Source: Voice of America .