Clamp,

Your theory is not flawed, I just didn't say it quite right. Quoting our training manual, "With the loss of both AC busses, flight beyond 30 minutes may result in complete loss of electrical power and the inability to extend the gear and flaps." The gear won't extend because of the closed shuttle valve and the flaps may not extend because of the loss of the center hydraulic system pumps and no electrical power to lower them with the alternate electrically driven system. Apparently the ADP isn't sufficient to power the flaps down by itself. From the pictures, it looks like all the flaps were down. From the reports I've read, they don't mention any electrical problems. Additionally, a catastophic electrical failure would certainly be cause for an immediate diversion. For these three reasons, I don't think they had an electrical problem, but if not, then why did they land gear up? If they did have one, then why didn't they mention it and why did they continue to destination? It doesn't make sense to me. If they had a system leak, I wonder where that fluid was going? Around some hot pumps perhaps. One thing they did have going for them if their aircraft was using Skydrol instead of Mil-H-5606. There are conditions under which Skydrol will burn, but Skydrol fluids are "fire resistant." Traditionally the term "fire resistant" has been used to describe phosphate esters, as opposed to mineral oil based hydraulic fluids, because they are very difficult to ignite at room temperature. In standardized testing, a fine mist spray of Skydrol cannot be ignited with an oxyacetylene torch. The same fine mist spray of a mineral oil hydraulic fluid, such as MIL-H-5606 or MIL-PRF-83282, produces a large fireball when touched by the torch. I nearly had to eject due to a hydraulic pump meltdown with MIL-H-5606.



P.S. Remember, the 757 doesn't have this problem. There should never be a scenario in the 757 in which all the gear fail to extend.