To: innuendo and NigelOnDraft
What I was alluding to was the root cause of the problem could be traced to the engine manufacturer and that was the leak. In any complex design the engineers must create a checklist to identify both maintainability and reliability design related problems and try to eliminate them from the design. One of those items on the checklist is to eliminate any thing in the design that would allow a part to be installed backwards. In the case of the Trent engine the fuel tube was designed with the same connection device at both ends of the tube. This may have been done to cut the cost of the fuel tube however the engine manufacturer must in this case tell the mechanic about the ability to install the part backwards and also provide instruction on how to establish the necessary clearance between the fuel and hydraulic tube. This was not done. By reversing the fuel tube the clearance will be eliminated. In this case the brand new engine was delivered with several parts missing including the fuel tube. Parts were cannibalized from another engine (which is allowed) and installed on the new engine. Because of the lack of specific instructions the tube was inadvertently installed backwards.
Pratt & Whitney and General Electric suffered a similar leakage of fuel due to abrasion between two metal lines. They each issued an AD telling the mechanic how to install the tubes and how to establish a minimum clearance between the two lines. These ADs were issued at least a year before the Airbus A-330 incident so I can only assume that the engine manufacturer was aware of this potential problem and they took no action. It is my understanding that after the incident Air Transat took delivery of another A-330 and upon inspecting the engines they found that the hydraulic line and the fuel line were contacting each other setting this aircraft up for the same situation.
