Bent 747 At Teesside Today
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Bent 747 At Teesside Today
Air Atlanta 747-200 TF-ATD scraped its tail while flaring on runway 05 this morning,inbound with troops from Calgary.It hit the undershoot area which is mainly gravel etc-It looks fairly grim on stand 1 with bent panels etc.This is the second 747 incident this week as TF-ATC overshot yesterday with flap problems diverting to Manchester on a full emergency!!-About time they got shot of these knackered old cans
Well, we've happily been flying troops back from CYYC over the past few weeks in aircraft far more ancient than any 747! Perhaps it's the gunner, not the gun which is at fault??
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The tail of two cities.
I can only assume that when they got the tail scrape there was a possibility that the pressure bulkhead may have suffered some damage. If this is the case I pray that the metal knockers have the assistance of Boeing in effecting the repair and that they have better luck than the Boeing techs and the Japanese metal knockers had on the Japanese 747 that lost its’ tail when the pressure bulkhead let go at altitude.
Cunning Artificer
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Lu,
Airline metal bashers [or knockers] do the job to an approved repair scheme, work to approved drawings and do as good a job as any manufacturer. Airline development engineers holding regulatory authority design approvals have all the relevant degrees, specialise in the repair field and know how to liaise with the right people to get any extraordinary data.
In our own recent 'Ramp Rash' incident at Heathrow, the 'Big Airways' own development engineer and metal knocking team did an excellent repair entirely in-house, except for the high-blow test after completion. [They could have done that too, but it isn't economical to keep such a special test rig lying around]. So, please don't knock the airlines until you've tried us. Those infamous ugly looking 'scab patches' though fully certified and stressed, are generally temporary, lasting only until the next long maintenance visit. (I admit that cheapskate airlines often leave them on permanently, but as I said - they are fully certified)
I well remember the 'Seattle Big Jets' AOG team who came to do a Service Bulletin on our Thrust Reversers and lived up to their name - they finished their own job but left us with a real 'AOG' and a poor impression - and it was after all, a 'Seattle Big Jets' team that screwed up the JAL repair...
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Through difficulties to the cinema
Airline metal bashers [or knockers] do the job to an approved repair scheme, work to approved drawings and do as good a job as any manufacturer. Airline development engineers holding regulatory authority design approvals have all the relevant degrees, specialise in the repair field and know how to liaise with the right people to get any extraordinary data.
In our own recent 'Ramp Rash' incident at Heathrow, the 'Big Airways' own development engineer and metal knocking team did an excellent repair entirely in-house, except for the high-blow test after completion. [They could have done that too, but it isn't economical to keep such a special test rig lying around]. So, please don't knock the airlines until you've tried us. Those infamous ugly looking 'scab patches' though fully certified and stressed, are generally temporary, lasting only until the next long maintenance visit. (I admit that cheapskate airlines often leave them on permanently, but as I said - they are fully certified)
I well remember the 'Seattle Big Jets' AOG team who came to do a Service Bulletin on our Thrust Reversers and lived up to their name - they finished their own job but left us with a real 'AOG' and a poor impression - and it was after all, a 'Seattle Big Jets' team that screwed up the JAL repair...
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Through difficulties to the cinema
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And "somebody" had screwed up using a "boiler plate" patch made of stainless steel over aluminum...on the China bird that had come unglued at TOC over the Taiwan Straits.
Last edited by GlueBall; 17th Oct 2002 at 12:45.
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That explains it then. Tuesday morning I was woken by an horrendous noise. I live about 5nm on the localiser for R23 and passing aircraft are not usually noticed.
But Tuesday a 747 (must have been TF-ATC) was banking sharply at about 1000' heading back across the localiser at what sounded like fullish power. I watched it track back towards lining up for R23, and once it had done that it again aborted, this time banking right. I never saw/heard it again.
Even the wife was concerned!
dgutte
But Tuesday a 747 (must have been TF-ATC) was banking sharply at about 1000' heading back across the localiser at what sounded like fullish power. I watched it track back towards lining up for R23, and once it had done that it again aborted, this time banking right. I never saw/heard it again.
Even the wife was concerned!
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Yes Blacksheep, they are fully certified, and yes you are right again in your statement that some airlines leave 'em on permanently.
But OTOH, when these same airlines are confronted with cracks in the patches, they get very defensive. Recall in one carrier, the F/E during walkaround (crew change) found a rather longish (three inch) split in the patch 'round the forward outflow valve, the company denied any responsibility. But then it got expensive, pax to hotac, aeroplane ferried to base, for you guessed it, another patch.
And jokeair, I suppose for "standards" you mean the events described in the first post...yes?
But OTOH, when these same airlines are confronted with cracks in the patches, they get very defensive. Recall in one carrier, the F/E during walkaround (crew change) found a rather longish (three inch) split in the patch 'round the forward outflow valve, the company denied any responsibility. But then it got expensive, pax to hotac, aeroplane ferried to base, for you guessed it, another patch.
And jokeair, I suppose for "standards" you mean the events described in the first post...yes?
Last edited by 411A; 17th Oct 2002 at 17:36.
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Yeah but....
To: Blacksheep
In the case of the Japanese 747 the tail scrape caused a crack in the pressure bulkhead. A repair was developed by Boeing and implemented by Japanese technicians under the supervision of the Boeing repair reps. Somehow the repair deviated from the design fix in that the rivet lines were not redundant. The repair failed and the rip stop construction of the aft bulkhead was compromised and the bulkhead failed. The debris entering the aft compartment damaged the three hydraulic systems causing loss of the flight control systems. There is a vent in the aft compartment to allow equalization of pressure as the aircraft changed altitude and to accommodate minor leakage of the pressure bulkhead and it was sized because of the rip stop construction of the bulkhead. Boeing tests showed that the bulkhead would never fail catastrophically. There is also a hatch or cover which when removed allows access to the inside of the vertical fin. I understand that this hatch cover was not in place, which allowed the escaping air from the cabin to enter the vertical fin over pressuizing it and causing structural failure and subsequent loss of the vertical fin and the rudder.
After the accident Boeing constructed a test rig to test both the structural integrity of the aft bulkhead and the level of pressure that would cause it to fail. The bulkhead would not fail catastrophically until the structure was compromised in a similar manner to the defective repair. When it did fail it blew a TV camera over 500 feet.
The point is that the manufacture does not always get it right nor do the technicians from the airline.
The aircraft and its’ passengers and crew might still be alive if Boeing had incorporated hydraulic fuses in the three hydraulic systems.
Airline metal bashers [or knockers] do the job to an approved repair scheme, work to approved drawings and do as good a job as any manufacturer. Airline development engineers holding regulatory authority design approvals have all the relevant degrees, specialise in the repair field and know how to liaise with the right people to get any extraordinary data.
After the accident Boeing constructed a test rig to test both the structural integrity of the aft bulkhead and the level of pressure that would cause it to fail. The bulkhead would not fail catastrophically until the structure was compromised in a similar manner to the defective repair. When it did fail it blew a TV camera over 500 feet.
The point is that the manufacture does not always get it right nor do the technicians from the airline.
The aircraft and its’ passengers and crew might still be alive if Boeing had incorporated hydraulic fuses in the three hydraulic systems.
Last edited by Lu Zuckerman; 17th Oct 2002 at 15:32.
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Design philosophy
To: 411A
I am, not at all familiar with the system architecture of the 747 however many commercial jets have more than three systems. The primary systems use engine driven pumps and most secondary systems are electrically driven and can be used to directly power one or more of the primary systems providing it is only because of a pump failure. In some cases there is a power transfer system which can use the electrically or engine driven pump in one system to power a hydraulically driven pump in the effected system. However in the case of the Japanese 747 the systems were compromised in that the plumbing had carried away which would negate the use of an alternate system. The only means left to the pilot to control the 747 was differential thrust just like on the United Sioux City DC-10 only the DC-10 still had an intact rudder to maintain longitudinal stability. The Japanese 747 just wandered about the sky until it hit a mountain.
I am, not at all familiar with the system architecture of the 747 however many commercial jets have more than three systems. The primary systems use engine driven pumps and most secondary systems are electrically driven and can be used to directly power one or more of the primary systems providing it is only because of a pump failure. In some cases there is a power transfer system which can use the electrically or engine driven pump in one system to power a hydraulically driven pump in the effected system. However in the case of the Japanese 747 the systems were compromised in that the plumbing had carried away which would negate the use of an alternate system. The only means left to the pilot to control the 747 was differential thrust just like on the United Sioux City DC-10 only the DC-10 still had an intact rudder to maintain longitudinal stability. The Japanese 747 just wandered about the sky until it hit a mountain.
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Glueball & 411A - I know that sometimes there are airlines that don't do the job right and there are occasions when stress calculations go awry. When cracks first occur, possible propagation paths are sometimes miscalculated. Lu is a real professional and I have the utmost respect for him, but I couldn't let his suggestion that the manufacturer always knows best, go unchallenged. I'm sure that Lu will be the first to agree that there are times when he reflects upon his work and worries if he got it right. Manufacturers don't always get it right and those in the Tech Services side of the business [like me for instance] earn our living from picking up the pieces and sweeping up after them.
The second crack in the external patch descibed by 411A is the result of poor understanding of the stresses involved in the original damage - the outflow valve area is notoriously difficult to get right. As it was, the inspection process caught the new crack at an early stage [don't skimp on your walk-rounds, they are the first step in the process], corrective action resulted regardless of the commercial costs and that is as it should be. As to aircraft patched with incorrect materials - there goes a rogue engineering outfit - draw your own conclusions and be careful who you fly with; it isn't as if they don't have a history.
In our company we aren't an approved design organization so all our repairs are passed through Boeing for review and given 8110-3 certification. But I don't sleep any better at night just because "Uncle Bill" Boeing says our repair is OK, its knowing the men with the rivetting guns personally that does that. There are airlines that don't do things properly but manufacturers need to be watched carefully too. Its discussions like this one that get things out in the open and let us keep everyone on the straight and narrow so, thanks for the chance to open out the discussion Lu. Lets keep professionalism alive...
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Through difficulties to the cinema
The second crack in the external patch descibed by 411A is the result of poor understanding of the stresses involved in the original damage - the outflow valve area is notoriously difficult to get right. As it was, the inspection process caught the new crack at an early stage [don't skimp on your walk-rounds, they are the first step in the process], corrective action resulted regardless of the commercial costs and that is as it should be. As to aircraft patched with incorrect materials - there goes a rogue engineering outfit - draw your own conclusions and be careful who you fly with; it isn't as if they don't have a history.
In our company we aren't an approved design organization so all our repairs are passed through Boeing for review and given 8110-3 certification. But I don't sleep any better at night just because "Uncle Bill" Boeing says our repair is OK, its knowing the men with the rivetting guns personally that does that. There are airlines that don't do things properly but manufacturers need to be watched carefully too. Its discussions like this one that get things out in the open and let us keep everyone on the straight and narrow so, thanks for the chance to open out the discussion Lu. Lets keep professionalism alive...
**************************
Through difficulties to the cinema
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I agrre with all of you post with one exception.
To: Blacksheep
This what I said.
“The point is that the manufacture does not always get it right nor do the technicians from the airline”.
From a design standpoint the pilots that fly a new aircraft are in fact test pilots because the aircraft is not always 100% and the structural engineers that design a fix are the same ones that design the aircraft. In the issuance of a new airframe to the flying public the manufacturer will issue all types of maintenance manuals one of which is the structural repair manual. This particular manual is constantly evolving because they can not include every repair that might be encountered. When a non-covered repair is designed it will be included in the next update of the manual. These types of repairs must be expedited because of the loss of revenue for the airline. A mistake might be made in their stress calculations but I believe in the case of the repair on the Japanese 747 pressure bulkhead the repair was well thought out but it was poorly implemented by the Japanese technicians and their error was not detected by the Boeing reps.
I have challenged many engineers relative to the reliability or maintainability of a design only to be rebuffed or receiving a lame excuse relative to the impact on the schedule or the cost of making the change and when the aircraft entered into service the identified problems manifested themselves. Cases in point are the A-310, the Apache, the V-22 and the EH-101 to name a few.
Here is an example of working on a Boeing contract. I did the FMECA and the reliability analysis on the Truck positioner used on the 767 landing gear. I requested information from Boeing on a pressure relief valve that they had designed and they refused to provide the information saying that it was proprietary. That left a big hole in the analysis. The designer made the Truck positioner in accordance with the stress levels provided by Boeing. When placed in test at Boeing the truck positioner would fail structurally. Boeing called in the designer and the stress engineer from the German Company that built the Truck positioner and they worked for over a month at Boeing to determine the cause of the failure. A Boeing stress engineer looked at the Germans’ calculations and asked why they were using the stress levels that were in their calculations for the design. He told them that the stress levels were much higher. When asked the Boeing engineer indicated that their initial calculations were incorrect but it was determined that they never relayed the new stress levels to the German company.
but I couldn't let his suggestion that the manufacturer always knows best, go unchallenged. I'm sure that Lu will be the first to agree that there are times when he reflects upon his work and worries if he got it right. Manufacturers don't always get it right and those in the Tech Services side of the business [like me for instance] earn our living from picking up the pieces and sweeping up after them.
“The point is that the manufacture does not always get it right nor do the technicians from the airline”.
From a design standpoint the pilots that fly a new aircraft are in fact test pilots because the aircraft is not always 100% and the structural engineers that design a fix are the same ones that design the aircraft. In the issuance of a new airframe to the flying public the manufacturer will issue all types of maintenance manuals one of which is the structural repair manual. This particular manual is constantly evolving because they can not include every repair that might be encountered. When a non-covered repair is designed it will be included in the next update of the manual. These types of repairs must be expedited because of the loss of revenue for the airline. A mistake might be made in their stress calculations but I believe in the case of the repair on the Japanese 747 pressure bulkhead the repair was well thought out but it was poorly implemented by the Japanese technicians and their error was not detected by the Boeing reps.
I have challenged many engineers relative to the reliability or maintainability of a design only to be rebuffed or receiving a lame excuse relative to the impact on the schedule or the cost of making the change and when the aircraft entered into service the identified problems manifested themselves. Cases in point are the A-310, the Apache, the V-22 and the EH-101 to name a few.
Here is an example of working on a Boeing contract. I did the FMECA and the reliability analysis on the Truck positioner used on the 767 landing gear. I requested information from Boeing on a pressure relief valve that they had designed and they refused to provide the information saying that it was proprietary. That left a big hole in the analysis. The designer made the Truck positioner in accordance with the stress levels provided by Boeing. When placed in test at Boeing the truck positioner would fail structurally. Boeing called in the designer and the stress engineer from the German Company that built the Truck positioner and they worked for over a month at Boeing to determine the cause of the failure. A Boeing stress engineer looked at the Germans’ calculations and asked why they were using the stress levels that were in their calculations for the design. He told them that the stress levels were much higher. When asked the Boeing engineer indicated that their initial calculations were incorrect but it was determined that they never relayed the new stress levels to the German company.
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Hi all,
In the midst of this back-and-forth discussion regarding aircraft repair integredy, I noticed the story about the Flight Engineer noticing the 'patch' problem on pre-flight walkaround, two comments:
a/ thank God we still have FEs to notice these things, and
b/ why wasn't the problem noticed during the ground engineers' walkaround?
Cheers
In the midst of this back-and-forth discussion regarding aircraft repair integredy, I noticed the story about the Flight Engineer noticing the 'patch' problem on pre-flight walkaround, two comments:
a/ thank God we still have FEs to notice these things, and
b/ why wasn't the problem noticed during the ground engineers' walkaround?
Cheers
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answering your 2nd question. when doing the same job, ie wac, everyone views thing from different angles. no one is perfect. ground engineer usually picking up the bad thingssss b4 flight engineer's wac. afterall both are all professionals.