What caused this 767 diversion?
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With a normal fuel load and no malfunction a scenario where you might get a LOW FUEL with an imbalance is leaving the crossfeed valves open.
Over time one side inevitably has more boost pump pressure than the other and an imbalance occurs much faster than with the crossfeeds closed (or so I'm told
). However, you should get a FUEL CONFIG when the imbalance reaches 2200 pounds, normally well before you get a LOW FUEL when the useable fuel drops below 2200 pounds in either main tank.
Over time one side inevitably has more boost pump pressure than the other and an imbalance occurs much faster than with the crossfeeds closed (or so I'm told
). However, you should get a FUEL CONFIG when the imbalance reaches 2200 pounds, normally well before you get a LOW FUEL when the useable fuel drops below 2200 pounds in either main tank.
As SLF I'm happy with the captain's decision to issue a mayday if he/she thinks it's warranted.
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Originally Posted by Herod
Like I said, it depends on fuel state. What you KNOW about the situation. I wasn't there, and I'd be the last person to criticise a captain's decision, having put out three maydays myself.
I suspect each MAYDAY occasion occurred in quick succession with a half second between each occasion.
Occasion 1: MAYDAY
Occasion 2: MAYDAY
Occasion 3: MAYDAY
As heard by ATC: MAYDAY, MAYDAY, MAYDAY (also known as putting out three MAYDAYS).
Like I said, it depends on fuel state. What you KNOW about the situation. I wasn't there, and I'd be the last person to criticise a captain's decision, having put out three maydays myself.
Occasion 1: MAYDAY
Occasion 2: MAYDAY
Occasion 3: MAYDAY
As heard by ATC: MAYDAY, MAYDAY, MAYDAY (also known as putting out three MAYDAYS).
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By a coincidence, I watched the same aircraft abandon an approach to Heathrow on April 5th. It seemed to start to go around about a mile from touch down. Nothing special about that, except various "spotters" noted the wheels remained down. And they remained down throughout the entire circuit back to making a successful landing.
As I was taking photos at the time, I compared the "before & after" pictures and it seems there was a difference in the setting of the inboard flaps, almost as if they had not fully deployed when the decision to go around was taken.
As I was taking photos at the time, I compared the "before & after" pictures and it seems there was a difference in the setting of the inboard flaps, almost as if they had not fully deployed when the decision to go around was taken.
"Mildly" Eccentric Stardriver
Originally Posted by Herod
Like I said, it depends on fuel state. What you KNOW about the situation. I wasn't there, and I'd be the last person to criticise a captain's decision, having put out three maydays myself.
I suspect each MAYDAY occasion occurred in quick succession with a half second between each occasion.
Occasion 1: MAYDAY
Occasion 2: MAYDAY
Occasion 3: MAYDAY
As heard by ATC: MAYDAY, MAYDAY, MAYDAY (also known as putting out three MAYDAYS).
Like I said, it depends on fuel state. What you KNOW about the situation. I wasn't there, and I'd be the last person to criticise a captain's decision, having put out three maydays myself.
I suspect each MAYDAY occasion occurred in quick succession with a half second between each occasion.
Occasion 1: MAYDAY
Occasion 2: MAYDAY
Occasion 3: MAYDAY
As heard by ATC: MAYDAY, MAYDAY, MAYDAY (also known as putting out three MAYDAYS).
One. Generator fell off its perch and severed an engine oil line. Low oil pressure warning, shutdown, mayday.
Two. Severe icing day. Very bad engine vibration, checklist called for shutdown, mayday. No fault found, and it was assumed a big chunk of ice separated from the wing and went into the (rear-mounted) engine.
Three. Structural failure of the rudder, resulting in hard-over situation. resultant sideslip caused an engine to fail due fuel starvation. mayday.
Since my original comment has set rats among the corn, this will be my last post on this thread. I say again, there was no criticism of the captain's decision.
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Old Lurker : LF refers to a "mate" of his. I know Lf and his mate referred to as well. In that case, he did have a time limited discussion with both Flt Ops & Maintenance Control as he sped by. He also displayed much airmanship by reducing speed in order to talk to the guys before heading from VHF to HF territory. It was just of interest that a similar incident resulted in vilification rather than support. Oh to have been in United !
Hazy recall of the fab 767 but I seem to remember basic thinking ; "Low Fuel" in any tank required placing all pumps on & X-feed open. In tank to engine, fuel imbalance was another drill & a sometimes the result of the low fuel drill. There was an imbalance limitation too. Get down to that limit with Xfeed open suggested you were feeding the leak so the Xfeed was closed. You now had a possible leak, identified & out of balance & with refined drills after the Airbus (I think) incident suggesting the Xfeed should be closed. Sim Tripper-uppers loved that scenario ,
On thread though, the question asked was why did he divert. Obvious to the pros here. I concur. Excellent decision because he was faced with a worrying problem, over the ocean with time consuming drills & analasys which might have led to very low fuel and lovely Kef floating away at 8 miles a minute.
Landflap's "mate" had a lovely discussion with a top train driver comparing lifestyles,pay, opportunities etc . Traindriver reckoned we were not worth the money we got because we were not doing anything (mid Atlantic & when FD visits were permitted). "Mate" responded ; " Well, at the moment, we are five miles above the planet earth & we doing eight miles a minute........and........if anything goes wrong, WE can't stop."
Enviable support from the Crew's employer as well.
Hazy recall of the fab 767 but I seem to remember basic thinking ; "Low Fuel" in any tank required placing all pumps on & X-feed open. In tank to engine, fuel imbalance was another drill & a sometimes the result of the low fuel drill. There was an imbalance limitation too. Get down to that limit with Xfeed open suggested you were feeding the leak so the Xfeed was closed. You now had a possible leak, identified & out of balance & with refined drills after the Airbus (I think) incident suggesting the Xfeed should be closed. Sim Tripper-uppers loved that scenario ,
On thread though, the question asked was why did he divert. Obvious to the pros here. I concur. Excellent decision because he was faced with a worrying problem, over the ocean with time consuming drills & analasys which might have led to very low fuel and lovely Kef floating away at 8 miles a minute.
Landflap's "mate" had a lovely discussion with a top train driver comparing lifestyles,pay, opportunities etc . Traindriver reckoned we were not worth the money we got because we were not doing anything (mid Atlantic & when FD visits were permitted). "Mate" responded ; " Well, at the moment, we are five miles above the planet earth & we doing eight miles a minute........and........if anything goes wrong, WE can't stop."
Enviable support from the Crew's employer as well.
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It wouldn’t surprise me if the MAYDAY was requested by ATC in order to facilitate the diversion. The North Atlantic is very busy most nights, and they won’t just clear all the other traffic out of the way without a good reason.
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Thanks for your patronising comment, JammedStab.
One. Generator fell off its perch and severed an engine oil line. Low oil pressure warning, shutdown, mayday.
Two. Severe icing day. Very bad engine vibration, checklist called for shutdown, mayday. No fault found, and it was assumed a big chunk of ice separated from the wing and went into the (rear-mounted) engine.
Three. Structural failure of the rudder, resulting in hard-over situation. resultant sideslip caused an engine to fail due fuel starvation. mayday.
Since my original comment has set rats among the corn, this will be my last post on this thread. I say again, there was no criticism of the captain's decision.
One. Generator fell off its perch and severed an engine oil line. Low oil pressure warning, shutdown, mayday.
Two. Severe icing day. Very bad engine vibration, checklist called for shutdown, mayday. No fault found, and it was assumed a big chunk of ice separated from the wing and went into the (rear-mounted) engine.
Three. Structural failure of the rudder, resulting in hard-over situation. resultant sideslip caused an engine to fail due fuel starvation. mayday.
Since my original comment has set rats among the corn, this will be my last post on this thread. I say again, there was no criticism of the captain's decision.
Hazy recall of the fab 767 but I seem to remember basic thinking ; "Low Fuel" in any tank required placing all pumps on & X-feed open. In tank to engine, fuel imbalance was another drill & a sometimes the result of the low fuel drill. There was an imbalance limitation too. Get down to that limit with Xfeed open suggested you were feeding the leak so the Xfeed was closed. You now had a possible leak, identified & out of balance & with refined drills after the Airbus (I think) incident suggesting the Xfeed should be closed. Sim Tripper-uppers loved that scenario ,
...... but basically it compares fuel used according to the engine fuel flow sensors with the fuel remaining based on the FQIS. If there is a large discrepancy (my memory says 7% but I wouldn't swear to that) it pops up an EICAS message (sorry, I don't remember the text).
Last edited by wiggy; 14th Apr 2018 at 06:09.
As noted, it was an FAA requirement. Timing of the implementation would have been different (updating EICAS s/w is a big deal), but the requirement was the same. So yes, 747-400/-8, 757, 767, 777, and 787 got more or less the same change - even that old antique 737 got something (even though it doesn't have an EICAS as such)...
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Herod, glad you are staying with it. Your experience & posts highly admired by most of us. You are also correct in the knowledge that an engine failure in a twin is a "Mayday". Actually, reference is to " a 50% loss of power". Two donks gone on a four-holer would also be an automatic Mayday.
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QRH 767
Hi ,
The 767 QRH states that if o FUEL IMBALANCE EICAS msg is shown ,the first suspicius is a fuel leak and then you will deal with the imbalance
later( after being sure there is no leak ).
Fly safe!
The 767 QRH states that if o FUEL IMBALANCE EICAS msg is shown ,the first suspicius is a fuel leak and then you will deal with the imbalance
later( after being sure there is no leak ).
Fly safe!
