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Just some respect for Will Fraser.:)
Gettin' "heretofore" into a thread scores double:ok: Now, can you work 'antidisestablisment' in there somewhere? ps I'm late on here but I understand BA have sussed out the problem and amended downline maint procs accordingly. Won't happen again. Nothing to see here - move along now. Sir George Cayley |
The Church of England
Sir George,
You could be right, any tendency for antidisestablishmentarianism to spread its wings within this thread should be encouraged at all costs. Sending Danny to Ireland or Wales seems the wrong way for PPruNe to go. Oh and its a long time since I used that word in anger ............. CW |
As humble SLF, I just find it so extraordinary that a twenty-year old aircraft model, with hundreds of examples in service and a long statistical history of perhaps millions of takeoffs, can be discovered at this late stage of its life to have a very serious logic bomb in its control software. Amazing, simply amazing... The trigger for this fault is an improper alignment between the reverser cowl and a cowl position sensor mounted, I recall, on the engine support strut (on two engines). Reverser cowl indication problems haven't been super rare, but sensor adjustment procedures have been changed in the past to make the indications less likely to occur. Any problem of this nature should be fixed within a maximum of 10 days (further narrowing the possibility that two engines should suffer the same fault on the same aircraft). Sometimes cowl adjustments have to be made, but groundtime and the skill/knowledge to do this job are not always present. Cheers NSEU |
As humble SLF, I just find it so extraordinary that a twenty-year old aircraft model, with hundreds of examples in service and a long statistical history of perhaps millions of takeoffs, can be discovered at this late stage of its life to have a very serious logic bomb in its control software. Amazing, simply amazing... |
Yes, it's the rarity of the event which makes it interesting - a 'black swan' piece of computer code which had lain dormant for five million takeoffs, if not more.
The sad thing for gamblers amongst the 747 pilot community is that at a one in 5 million risk, you were still nearly three times more likely to experience this set of circumstances than to win the national lottery jackpot (1 in 14m odds)! |
When you talk of odds, you need to think 744/RR, this one has a long history of Rev probs, both Ind and operation, the 744/GE/PW have few problems.
. Cheap lesson, well done to the 056 crew. |
...and of course of all places for it to happen, it had to happen in JNB, one of the highest altitude airfields on the BA route map.. talk about the potential for holes in the cheese....
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When you talk of odds, you need to think 744/RR, this one has a long history of Rev probs, both Ind and operation, the 744/GE/PW have few problems. The GE and PW configurations differ from the R-R in that they use the thrust reverser auto restow sensor signal rather than the thrust reverser unstow sensor to automatically retract the LE flaps. Thus, for GE and PW configurations, the Group A LE Flaps will automatically retract if the aircraft is on the ground and either reverse thrust is selected via the reverse thrust levers of both outboard or both inboard engines or an auto-restow signal is received from both outboard or both inboard engines. While the rate of auto-restow events on the GE and PW engines is lower than the rate of unstow indications on the R-R engines, and no dual auto-restow events are known to have occurred, the Boeing SRB determined that the result of a dual symmetric auto-restow event is a safety issue and a safety SRP was initiated for both engine types. The Ref /C/ and /D/ SRPs were initiated for the PW and GE engines respectively. We are planning to hold technical teleconferences within the next two weeks to further discuss the Boeing SRB decision and answer any operator questions. Additional information on these telecons will be provided via follow-on communication. Further updates will also be provided in the Ref /B/ Fleet Team Digest article. |
Until recently, SAA were flying B747's with all three engine types, out of JNB :bored:
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Does anybody know any further information into the investigation?
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Think I heard the FCUs will be looking for another input before they retract the L/E flaps, may be a 20% or 30% TLA/TRA or wattever it's called, thought it was due before year end(2009), may be it's not so simple, 056 crew did a good job by all accounts.
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All 747's are not created equal. With the exception of the SP (not sure about that one), all will retract the 'Group A' LE Flaps upon receiving a 'ground' signal from the A/G logic AND receive signal from the thrust lever that reverse thrust has been selected. Retraction of the Group A devices based on either #1 & #3 OR #2 and #4 T/R position was added as basic to the 747-400's (certified in 1989) as well to provide additional redundancy to the system design. The concept of LE flap retraction mitigates fatigue damage to the flap panels from the reverse thrust. The Group B panels do not retract; these are outboard of engines #1 and #4.
The Boeing S/B changes the signal wiring to the Flap Control Unit such that 747-400's will retract the LE devices only upon selection of reverse thrust - making them the same as the older 747's There is an additional S/B for the 747-400's which changes the position of the signal switch in the thrust handle that triggers reverse thrust selection until AFTER the interlock position of the reverse thrust handle. This bulletin is independent of the FCU wiring change and was the result of LE retraction during take off when the reverse handles contacted a book on the isle stand just enough to signal reverse thrust during selection of TO thurst. ...and I will toss my Kudos to the 056 crew as well - great job.... |
SouthpawSLF said it, kudo's to the crew of 056.
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The sad thing for gamblers amongst the 747 pilot community is that at a one in 5 million risk, you were still nearly three times more likely to experience this set of circumstances than to win the national lottery jackpot (1 in 14m odds)! If the average person buys 52 lines per year then in their adult life time of say 60 years their odds of winning the lottery are 1 in 4487 If they fly an average of 2 sectors per year in a 747 their odds of experiencing this failure are 1 in 41666 Therefore you are actually almost 10 times more likely to win the lottery. Don't you just love statistics! |
Gamblers amongst the pilot community, not SLF
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http://img.photobucket.com/albums/v1...banner_600.jpg The Master's Medal Awarded to any person in aviation, at any time, for an act or achievement in aviation considered worthy of the Medal, as soon as the facts of the event are clear. CAPTAIN MICHAEL FAIRHURST & SENIOR FIRST OFFICER JAMES BROWN Citation: On 11 May 2009, during a normal Boeing 747-400 departure from Johannesburg, with the First Officer as the handling pilot, the Number 3 engine Thrust Reverser 'In Transit' indication appeared at 125 knots followed by the Number 2 engine Thrust Reverser 'In Transit' indication at 160 knots. There was no deployment of thrust reverse and the 'In Transit' indication is not easily visible and was not seen by the crew who were concentrating on the take-off. At this point the Group A sections of the leading edge flaps, which are a significant proportion of the leading edge high lift devices, retracted as they are designed to do when reverse thrust is selected on landing. Unaware of the changed leading edge configuration, the First Officer rotated the aircraft and the crew were immediately confronted with significant airframe buffet and the stick shaker activating. The crew had no idea why the aircraft had apparently entered a stall or pre-stall regime. As they were dealing with the emergency the Group A section of leading edge flaps started to re-deploy shortly after the aircraft became airborne. The First Officer flew an attitude that prevented the aircraft stalling but also prevented contact with the ground despite being unable to read the instruments clearly due to the buffet. The Captain calmly supported the First officer by passing on critical information such as speed and aircraft height above the ground. He also raised the landing gear. The handling difficulties were initially made worse by the increase in drag created by the opening of the landing gear doors during the retraction process and the initial movements of the leading edge flaps as they started to redeploy. After the leading edge flaps had re-extended (taking 23 seconds) the aircraft performance returned to normal and the handling aspects of the event were over. The crew still had to deal with an unknown set of circumstances. They decided to return to Johannesburg and planned for two, three and four engine approaches given the unknown nature of the fault. They also ensured that customers and the cabin crew were kept informed and remained calm and relaxed throughout. Captain Michael Fairhurst and Senior First Officer James Brown displayed exemplary skill and professionalism while dealing with this emergency that occurred at a critical phase of flight. Both members of the flight crew played a significant role in recovering the aircraft safely from the very hazardous situation they were confronted with. Their actions undoubtedly saved the aircraft, and countless possible injuries or fatalities to those onboard, and they are accordingly awarded the Master’s Medal. The Medals were awarded to the pilots some time ago and formally presented at the Guild's annual 'Trophies and Awards Banquet' at the London Guildhall at the end of last month. GAPAN - The Guild of Air Pilots & Air Navigators Patron: HRH The Prince Philip, Duke of Edinburgh Grand Master: HRH The Prince Andrew, Duke of York . |
Very worthy recipients of the award - well done chaps, very proud of you:D:D:D
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cracking effort chaps... well deserved :D:D
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Fantastic ....
very well deserved... truly a professional performance.
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This has got to be the same James Brown who does aeros at While Waltham! I can't believe BA has 2 SFOs on the 744 with the name James Brown!! :p If so Well done James and also your colleague Captain Micheal! Excellent airmanship - would have expected nothing else from you!:D
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