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Crash at Sharjah airport

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Crash at Sharjah airport

Old 13th Nov 2009, 12:46
  #181 (permalink)  
 
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OK EGOS massaged

Now back to the thread.

Please.

The Dubai air show is this week, perhaps some news will escape from the GCAA.

SSA
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Old 20th Nov 2009, 20:16
  #182 (permalink)  
 
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Re "training" and "finest of...etc", has training changed to accomodate automation today or has the bottom line driven training to new lows in the expectation that automation will "look after the store"?
Just read through a B787 sales presentation from Boeing, time and again it mentioned potentials for reduced training. Definitely a point aimed at the bean counters. 8 days "differential training" from the 757/767.
Seem descent knowledge and training to proficiency has been thrown out.
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Old 20th Nov 2009, 22:26
  #183 (permalink)  
 
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CIRCUITB
"The STN event you mention was caused by maintenance error....someone assuming someone else was securing the cowls......"

This comes under the Human Factors banner nowadays. The people involved were all competent & conscientious, but old fashioned job demarcation played a part.
Anyway this is not really relevant to this thread.
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Old 21st Nov 2009, 17:00
  #184 (permalink)  
 
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Cowlings again.......

CIRCUITB Yr post #183.....

Nope....wasn't me who said that, it was GAZIN, above.

The incident of cowling failure that I remarked on at the top of page 9 resulted from a manufacturing fault. I haven't read the content of my 707 ops manuals in any depth since consigning them to the far reaches of my loft in 1980. Documents from the enquiry might even co-exist, so I will enlarge on my initial sentence above by saying that to the best of my recollection the finding was that one (only) of those over-centre lever type locking devices was mis-aligned at manufacture. Assuming that the failed cowlings were the original pair as supplied new to Airlift International, the inference was metal fatigue/distress over the period of time. The fault was assessed as not observable on a standard walk round pre-flight check.

As per schedule, we returned to base on a passenger service a couple of days after the freighter to be informed that a verdict of 'Pod Scrape' had been handed down from a high placed non-aircrew source that perhaps it's tactful not to identify - even if I could remember all this time later. Now, the Captain who was a US citizen on contract, and both engineers failed to see much amusement at this pronouncement, and without hesitation borrowed/stole/impounded the cowlings for scientific examination.
The independant test findings resulted in our being personally handed letters of mild commendation, a cup of tea, and probably a biscuit.
Only a cynic would wonder if pilot handling errors attract faster insurance settlements. I remember that possibility being raised at the time, but not by anyone with specific knowledge of our company.

I never worked for Dan Air, but was closely involved with the aftermath of the Lusaka tragedy. To the best of my recollection, the aircraft had been on check in the BCal hangar at LGW not long before the incident. The criticisms did not involve anything to do with the stabilizer, but there were a couple of things that should have been fixed before Dan Air operated it.
Had the accident first happened to one of the passenger versons of similar vintage then in operation, long-term media and public reaction would have been markedly different. In the case of both the Lusaka and the recent Sharja incident, it's just so sad that the relatively low number of victims only briefly interest the media and mask the public's interest in the truly shocking causes of structural failure.

Last edited by ONE GREEN AND HOPING; 21st Nov 2009 at 21:45.
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Old 24th Nov 2009, 01:17
  #185 (permalink)  
 
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Now, the Captain who was a US citizen on contract, and both engineers failed to see much amusement at this pronouncement
No wonder!
...and without hesitation borrowed/stole/impounded the cowlings for scientific examination.
The independant test findings resulted in our being personally handed letters of mild commendation, a cup of tea, and probably a biscuit.
Good for the crew concerned.
Well done.
My opinion...never take cr*p from anyone when you know darn well you are right.
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Old 24th Nov 2009, 04:50
  #186 (permalink)  
 
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I believe the B 707 was the queen of the skies. It was also one the strongest "civilian" aircraft Boeing built. IMHO it was the last of the real aeroplanes. It has only one powered primary control and that is the rudder. The rest is cables, pulleys etc., and it still could be flown with a very light touch. It did need a certain amount of finesse and correct technique in cross winds, for E.G.

There is/was a B 707 engaged in short haul cargo operations, round trip fuel, (landing weight "limited") that I know for a fact has been landed on average, 10 tons over MLW, 2 times per day for over 10 years, more like 15 years. No other aircraft in it's class would take anywhere near that sort of punishment and abuse and keep going.

As far as this accident maybe concerned I would like to add this. "If you flex or bend a piece of metal long and often enough, it will fail". The trick is to find where it intends to fail before it actually does.

Last edited by screwballburling; 24th Nov 2009 at 05:02.
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Old 24th Nov 2009, 11:58
  #187 (permalink)  
 
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Curiously there has been no mention in this thread of the want of a third, fail safe spar in the horizonal stabiliser on the B707 in the design office - might have saved them - never know. A great read is, J M Ramsden, "Caring for the Mature Jet", released after the Lusaka accident. I learnt and absorbed all my basic mechanical flight control basics on the B707 that still hold true today . . . I got lucky and went on to the B727-200ADV for a few years after that and never looked back !
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Old 24th Nov 2009, 12:19
  #188 (permalink)  
 
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"If you flex or bend a piece of metal long and often enough, it will fail".

This aircraft - whilst with Nile Safari operated KRT-JUB many many times with no fuel in JUB and therefore would have been subject to perhaps more than it's fair share of overweight landings (and high G spiral approach and departures). Not saying that was the cause but I agree with screwballburling.
CM
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Old 24th Nov 2009, 17:52
  #189 (permalink)  
 
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"If you flex or bend a piece of metal long and often enough, it will fail".
I hate to see these threads divert so far from the factual subject at hand.

The metal fatigue is a fracture mode and not a failure mode when it comes to complex structures like aircraft. It is well known that many parts of the aircraft flex, bend and crack in metal fatigue all the time. The idea behind maintenance programs is to find the big cracks that have grown beyond acceptable limits. Since no new factual information has surfaced this idea is just another form of idle speculation.
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Old 25th Nov 2009, 00:16
  #190 (permalink)  
 
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Structural Integrity

All,

When G-BEBP lost its stab as flap 50 was selected, even though slowing and set up for landing, departure from S&L was immediate, with no recovery prospect. It impacted just beyond the vertical.

If ST-AKW suffered a stab loss, her behaviour would be the same. If the stab was damaged (by the departing cowling), pitch, and not roll control would have been immediately affected. This is not the case.

5N-MAS proved a heavy 707 can fly having suffered Nos 3 and 4 physically depart the airplane, and with the right wing in flames for 12 minutes, to a text book landing at Istres.

N761PA lost 27ft of its RH wing and the No. 4 engine on T/O from SFO when a T3disk ruptured, and the reserve tank exploded. Operation of the inboard high speed airleron was impaired, but the aircraft remained controllable.

When OD-AGO collided with an TAF F-5 in 1979, it lost the entire vertical stabiliser at FL110, with the Captain's comment about "slight control anomoly".

The 707 can suffer complete retraction of the L/E devices (as in a total hydraulic failure), with little effect on an airplane in excess of 130 kts.

The above shows the 707 can fly with major structure missing in the empennage and wing (except the horizontal stab), engines missing, flight controls seriously imparied or missing, or the L/E devides retracted.

There are really only two likely scenarios for this tradegy.
1. The airplane got too slow too quickly after the No. 4 engine failure, and with high power set for its climb, once it started into its right turn towards the failed engine, it kept going, and with the wings vertical, gravity, insufficient time adn altitude did the rest -OR-

2. The departing cowling from No. 3 or 4 impacted a T/E flap, or the T/E flap seperated for some other reason, pulling the aileron bus cables (run just in front of the flap) and applying full right aileron. Remeber both high and low speed ailerons were operable in this regime, and you know the airplane's roll rate.

Take another look at the size of the "object", and its trajectory. Its big enough to be either an inboard or an outboard flap. Does the light "sycamore leaf" cowling fall staight down, or would it not tumble ??

Tweedler
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Old 25th Nov 2009, 03:49
  #191 (permalink)  
 
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I am not aware I wrote that metal fatigue or general wear and tear was the cause of this accident. It may have been a contributing factor.

I do believe the bit that detached from the aircraft, shown in the security camera footage was bigger than an engine cowl. I believe it was a TE flap or part of.

What I am sure happened is the crew lost control of the aircraft. that is self evident. Why? Who knows but low speed would have entered the equation. Judging from the film clip the stabilizer was still intact before it hit the ground. whether they had any use out of it may have been another matter.

All speculation, nothing more.
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Old 25th Nov 2009, 07:50
  #192 (permalink)  
 
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Tweedler,
A very well written post, especially nice for a first post. Interesting, given your join date. Your scenario #1 seems very likely and VERY familiar, let's see if you get flamed like I did. lol
On the other hand,,,
Let's, for arguement sake suppose that the falling object is a T/E flap: Well, we're back to good climb angle and all engines producing thrust. Lower the nose and accelerate,, speed is options, speed is life. Speed is more aileron, speed is more rudder. A total assymetric flap on one pair is no life threatening deal in a 707,, given enough speed.
Granted,, we never practised flap assymetric take offs.
My money is still on a slow speed turn into a dead engine.

--Heracles
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Old 25th Nov 2009, 23:43
  #193 (permalink)  
 
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Structural Integrity 2

Thanks for your comments Heracles.

We are in accord on the possibility of the slow turn into the dead engine being causal. The problem I have with this is the experience level of the crew. By all accounts it was good. With the WX severe clear, a perfect horizon outside, and an airplane comfortably below MTOW, such a crew would generally be expected to pick up a falling wing before its too late, even if momentarily startled by a structural “bang” or failing engine. Its been drummed into all of us that if we are to hit, doing so as close to S&L means we might walk away, so the primary instinct when this low and slow will be wings level, and chase that life saving speed you rightly referred to.

Because the airplane never even started to pick up the low wing, I feel that the crew may have been confronted with a structural “hard over”, which they physically couldn’t overcome in the time and altitude window available.

That got me back to the “object”, and reverse engineering my way into what could cause such a “hard over” event. A separating inboard or outboard flap can occur if the flap track fails at the attach face, or there is a serious corrosion condition in the rear spar where the track attaches. The outboard flap is immediately adjacent to the low speed aileron lock out quadrant. The aileron bus cables run just in front of both flaps. As it was with the THY and AA DC-10 floor collapses snagging primary control cables, it would be technically possible for a separating flap to pull any element of the aileron cable system and cause a “hard over”. Such a structural “jam” rapidly sets up the slow speed turn into the dead engine with a predictable outcome.

Does anyone have any information on the CVR / FDR de code yet ? I think I saw a post that said noting can or has been retrieved.

Regards
Tweedler
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Old 27th Nov 2009, 09:37
  #194 (permalink)  
 
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refocus

Hear hear.
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Old 29th Nov 2009, 17:50
  #195 (permalink)  
 
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Citation Needed

One Green and Hoping

Quote:
I never worked for Dan Air, but was closely involved with the aftermath of the Lusaka tragedy. To the best of my recollection, the aircraft had been on check in the BCal hangar at LGW not long before the incident. The criticisms did not involve anything to do with the stabilizer, but there were a couple of things that should have been fixed before Dan Air operated it.

I worked in Hangar 3 - don't remember this aircraft at all. Inference is that BCal should have fixed something ?? Major was done at Dan-Air Maintenance Facility in the AAIB report. Aircraft had done 146 cycles since C Check. BCal MX may have lent the Dans boys the hangar for the night for the B Check but I dont think that they'd have been looking for cracked lugs on the upper stab bushings - do you?

Sorry to be a little sensitive when it comes to MX malpractice but it tends to touch a nerve. Foxy.
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Old 1st Dec 2009, 11:55
  #196 (permalink)  
 
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Foxy2600

Correct, the aeroplane had been on check at Lasham. Story we were told at Dan Air Gatwick was that a crack was known about and being monitored for propagation every turnaround by a flying spanner, who unfortunately perished with the others.don't recall where said crack was but I seem to think they were looking at the skin just fwd of the stab and were not actually aware of the major cause of this problem. Apparently during the check some pulled rivets were being replaced in this area when a whole length of the seam 'popped', as far as we know this indication of stress did not ring any alarm bells and the effect was monitored rather than the cause.
All of the above is second hand, I did not personally witness any of it.
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Old 1st Dec 2009, 14:26
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Heracles , post #163:
A wiki page already?, wow.
Thanks to guys who still frequent the gulf for keeping an ear open.

For future reference, the cowling on the older Pratts are NOT ATTACHED to the aircraft at the top. The very old (dating myself here) J-57's, the TF-33/JT-3's, and the JT-9 series motors cowlings upper hinge is simply a curved blade that rests in a "cage" of rollers. There is no mechanical hinge per-se. Combine that with the curvature of the upper edge of the cowl,, it's VERY easy to miss-align and still close these cowls. They will latch at the bottom and be very obviously out of rig at the top. More often than not the ground engineers will simply waste alot of effort trying to get all 5-7 of them to line up,,, it's an "art".lol
Not saying that it's particularly relevent here, just adding to the knowledge base when I can.
These cowls a bl**dy lethal. They were also used on early JT9D engined 747s. It was very easy to unhook them when lifting the cowling just a little above the level at which the hold open rod could be engaged. And since they were quite heavy, there was always the danger of them falling down on you.
I once got stuck for half an hours standing on a stepladder trying to prevent a partially unhooked #4 engine 747 cowling from falling down down on me, until a colleague happened to pass by, whom I could call for help to get the thing back into position again.

Also, on closing, the hooks had to be perfectly aligned in their roller cages, else the cowling would jam and couldn´t be closed. It was an art to hit just the right spot with the flat of your hand to get then to align.
Similar cowls were also used on the Pratt engined 737s, but there the distance to ground wasn´t that high, you didn´t need to stand on a ladder to open or close them, so they were not that dangerous (though you still could close them incorrectly).

Jan
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Old 2nd Dec 2009, 07:55
  #198 (permalink)  
 
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MD11eng,
You've obviously wrestled with a few JT-9 cowls,, a little slice of heaven 'eh mate?
I merely ment to point out that on the JT-3 powered 7 oh's, the lack of curvature in the upper mounting surface as compaired to the JT-9, or even the un-reverse cowled J-57,, it was actually possible to close the cowl latches with one or more of the upper blade hinges out of alignment (I've seen it done.).. Possible,, but not without a rediculously mis-aligned upper cowl to pylon joint. Which no-one associated with aviation could fail to take notice of.
This wasn't "loose" or "mis-aligned" cowling halves impishly waiting untill first segment climb to detatch themselves and wreak havoc on the rest of the aircraft. Something blew the cowling off,, that is IF the falling object actually is cowling.
Either that, or I'm wrong.
--Heracles
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Old 2nd Dec 2009, 22:37
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What could 'blow' a cowling off?...curious

above all other emergencies, engine separation is my most feared...I don't think even today anything is written down...helpful, I mean

PA
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Old 8th Dec 2009, 09:27
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Over flew site at SJH Yesterday

Not able to get any pics, due to distortion out of window, due the angle, will try again tomorrow.

However there was a fire, with lots of smoke, (on the other side of the airport).

Which reminds me that I have seen 3 big fires in the Industrial Areas in the last two months.

Has any one else been into out over SJH, and got pics of the site, to get an overview of the debris field.

glf
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