Mitch Cronin Posted March 25, 2008 Share Posted March 25, 2008 Anyone know anything yet?? Have I slept through some revelation someplace or is something being quietly swept under a rug somewhere?... or what? ...anyone?? Link to comment Share on other sites More sharing options...
Guest rattler Posted March 25, 2008 Share Posted March 25, 2008 seems to be all quiet for now. The following is not specific to the BA incident but may be of interest. The BA aircraft was said to have lots of fuel but what if it wasn't in the right tanks? SUBJECT: 777-300ER/777-200LR Failure to Scavenge Fuel /A/ Service Related Problem 777-SRP-28-0118 /B/ Fleet Team Digest Article 777-FTD-28-07002 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - SUMMARY: Note: This message contains important information relevant to flight operations and airplane dispatch, please distribute accordingly. Several 777-300ER operators have reported intermittent occurrences of airplanes landing with as much as 2200 lbs/1000kgs/300 gallons of fuel in the center tank. Boeing theorizes that this is an indication that the fuel scavenge system has malfunctioned. A failure such as this of the fuel scavenge system reduces the range of the airplane and could potentially lead to fuel exhaustion in the event additional failures occur which require use of all planned reserve fuel. To address this concern, Boeing recommends that 777-300ER and 777-200LR operators review their fuel reserve policy to ensure adequate reserves exist for each mission. - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - DESCRIPTION: The scavenge system is designed to transfer fuel from low areas of the center wing tank to the main tanks after the override pumps are shut off. Scavenging this additional fuel from the center tank increases the fuel available for engine use. The 777-300ER and 777-200LR airplanes have incorporated scavenge system design changes intended to increase the amount of fuel scavenged and reduce the amount of trapped unusable fuel in the center tank to approximately 3 gallons. These changes included relocating the fuel scavenge inlet further inboard, while the water scavenge inlet location remained unchanged. Additionally, the fuel scavenge outlet and float valve were moved further outboard to allow fuel scavenge to be initiated earlier in flight. Several 777 -300ER operators have reported intermittent occurrences of airplanes landing with as much as 2200 lbs/1000kgs/300 gallons of fuel in the center tank. Boeing theorizes that this is an indication that the fuel scavenge system has malfunctioned. These instances have only occurred on long routes originating from colder climates and have led to the conclusion that an excessive amount of water is entering the fuel scavenge system and is freezing during scavenge operations (and for sumping?). Because the water scavenge inlet was not co-located with the fuel scavenge inlets it is more likely for water to be ingested into the scavenge system. Additionally, as the outlet float valve location is further outboard in the main tank than previous, the scavenged center tank fuel has more exposure to the cold soaked main fuel tank prior to reaching the scavenge discharge. Indications are that the water in the scavenge system is freezing prior to discharging in the main tank. Frozen water (or ice) in the scavenge system could result in a low rate of scavenge or no fuel scavenge. (But ice in the form of melting slush?) Failure of the fuel scavenge system could result in airplanes landing with as much as 2200 lbs (1000 kgs) of fuel in the center tank. During mission planning and dispatch, this fuel in the center tank was considered usable fuel. However, failure of the fuel scavenge system in flight renders this 2200 lbs (1000 kgs) of fuel as unusable. There is no indication to the flight crew that the scavenge system has failed nor that the fuel is unusable. Failure of the fuel scavenge system essentially reduces the range of the airplane and could potentially lead to fuel exhaustion in the event additional failures occur which require the use of all planned fuel reserves. Boeing review has determined that the failure to completely scavenge the center tank is the result of system configuration changes unique to the 777-300ER and 777-200LR airplanes. This issue has been placed in our Service Related Problem (SRP) process for resolution and is the subject of the REF /B/ Fleet Team Digest article. DESIRED ACTION =============== Boeing recognizes each operator establishes its own fuel reserve policy. Some operators choose to add additional conservatism to existing regulatory fuel reserve requirements. In addition, we note that not all routes and/or operators have shown a susceptibility to this condition. This may be because of environmental conditions, individual airline water sumping policies, or different operator fuel system procedures. Boeing suggests 777-300ER and 777-200LR operators review their operation for exposure to trapped center tank fuel and their maintenance policy related to water sumping. We recommend operators establish a policy to monitor center tank fuel quantity upon arrival of each flight. If trapped center tank fuel above 400 lbs (200 kgs) is discovered, we recommend a further review of fuel reserve and maintenance policies as noted above. If operators chose to address this issue by uploading additional fuel, Boeing recommends operators notify their flight crews that additional fuel has been loaded to mitigate the potential for up to 2200 lbs (1000 kgs)of unusable fuel following failure of the scavenge system. For operators who have seen the trapped center tank fuel condition and chosen to adjust their fuel reserve policy, we recognize it may be possible for this condition to be resolved on future flights due to a change in environmental conditions or maintenance practices.. If this situation arises, we believe it appropriate to adjust fuel reserve policies to original levels provided they continue the monitoring policy on a flight by flight basis for trapped center tank fuel. Although these failure to scavenge occurrences have only been reported on the 777-300ER, any Boeing recommendations should also be applied to the 777-200LR as it has an identical center tank fuel scavenge system. If further information is needed regarding the subject, please contact your local Boeing Field Service Representative. If your local Field Service Representative is unavailable, you may contact the appropriate Airline Support Manager or call the BCA Operations Center at (206) 544-75 Link to comment Share on other sites More sharing options...
Fido Posted March 25, 2008 Share Posted March 25, 2008 The BA aircraft was a 777-200ER was it not? The way that I read this bulletin it refers only to the newer -300ER and -200LR. Link to comment Share on other sites More sharing options...
Guest rattler Posted March 25, 2008 Share Posted March 25, 2008 The BA aircraft was a 777-200ER was it not? The way that I read this bulletin it refers only to the newer -300ER and -200LR. I only posted the item for information on the chance that the various 777 aircraft types might share some common systems perhaps Mitch can provide some input. Link to comment Share on other sites More sharing options...
mo32a Posted March 27, 2008 Share Posted March 27, 2008 A friend sent this concerning the Boeing 777 that crashed short of the runway in London a few weeks ago. I make no claims as to the veracity of the information.> > > Well, the British aircraft accident investigation board has finally > come around to the conclusion that I made several weeks ago: the > event was > RF-induced. > > Prime Minister Dr. Gordon Brown's motorcade was passing under the > approach path of BA038. His security system utilised a RF > transmitter to block out > any cell-phone triggered devices. Apparently this system has a two > mile > range, and it caused the Boeing 777 EEC's (electronic engine > controls) to sense a > "overboost" situation, thereby commanding a reduced-thrust > situation for > the engines, simultaneously. Most interesting. > > We'll see how Boeing and the BAA handle this one. This could be > potentially bad, in view of the simplicity of technology that the > bad guys > could use to bring down an airliner. > > > Link to comment Share on other sites More sharing options...
GDR Posted March 27, 2008 Share Posted March 27, 2008 I received that report as well. I have to think that if it is true then everything possible would have been done to keep it out of the public domain for obvious reasons, which causes me to doubt thte story. However if it is true then I guess the cat is out of the bag so to speak. Link to comment Share on other sites More sharing options...
Timothy Posted March 27, 2008 Share Posted March 27, 2008 The possibility of radio frequency interference is an interesting hypothesis, but shouldn't any susceptible divices on the plane be properly shielded? Link to comment Share on other sites More sharing options...
J.O. Posted March 27, 2008 Share Posted March 27, 2008 I got that one too, but here's the thing. The information from the FDR shows that the FMS called for an increase in thrust and that the FADECs responded to the call, causing the engine fuel valves to move to full open. The back driven thrust levers also moved forward with the call for an increase in thrust. From what I know of the system, it did everything to attempt an increase in thrust, and yet the increase didn't happen. While they haven't overtly stated this yet, the focus seems to be on a physical blockage in the fuel flow. I'm not saying that RF interference isn't worth investigating, but if they are looking at it, the information they've released to date is an excellent example of how to divert attention away from it as a controversial issue. Link to comment Share on other sites More sharing options...
RFL Posted March 28, 2008 Share Posted March 28, 2008 A friend sent this concerning the Boeing 777 that crashed short of the runway in London a few weeks ago. I make no claims as to the veracity of the information.> Sounds like something from the Chemtrails Society. Link to comment Share on other sites More sharing options...
mrlupin Posted May 15, 2008 Share Posted May 15, 2008 http://www.theregister.co.uk/2008/05/13/aaib_777_update/ Link to comment Share on other sites More sharing options...
Mitch Cronin Posted May 15, 2008 Author Share Posted May 15, 2008 Thanks Eric! .... and from this: http://www.aaib.dft.gov.uk/cms_resources/S...08%20G-YMMM.pdf - "In addition, work has commenced on developing a more complete understanding of the dynamics of the fuel as it flows from the fuel tank to the engine." Now we might be getting somewhere! Link to comment Share on other sites More sharing options...
Guest woxof Posted May 15, 2008 Share Posted May 15, 2008 Mitch.... If you want to stay up to date on the latest romours and facts on this case then go here. As of recently, you have to register to access this site due to the heavy traffic after this accident. http://www.pprune.org/forums/showthread.php?t=325095 Link to comment Share on other sites More sharing options...
J.O. Posted May 15, 2008 Share Posted May 15, 2008 Mitch: The thread on PPRuNe is pretty good, but there's an awful lot of chaff among the kernels of wheat. I think you're smart enough to see the difference. Link to comment Share on other sites More sharing options...
Steam Driven Posted May 16, 2008 Share Posted May 16, 2008 I remember reading a while back with the advent of the next Gen flight decks the FAA requiring more stringent HIRF tests. I believe it was to stop just this sort of thing from happening... SUMMARY: This final rule amends FAA regulations by adding airworthiness certification standards to protect aircraft electrical and electronic systems from high-intensity radiated fields (HIRF). This action is necessary due to the vulnerability of aircraft electrical and electronic systems and the increasing use of high-power radio frequency transmitters. This action is intended to create a safer operating environment for civil aviation by protecting aircraft and their systems from the adverse effects of HIRF. DATES: These amendments become effective September 5, 2007. Link to comment Share on other sites More sharing options...
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