Old jets' wires may be riddled with cracks
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Old jets' wires may be riddled with cracks
10/10/00- Updated 10:47 PM ET
Old jets' wires may be riddled with cracks
By Gary Stoller, USA TODAY
Old airline jets may be flying with thousands of cracks in their electrical wiring, based on a USA TODAY analysis of a new Federal Aviation Administration report.
The report, which is being released Wednesday, was put together by an FAA task force that hired electrical engineers to test wire on six jets, each at least 20 years old.
A Boeing 747, an Airbus A300, a Lockheed L-1011 and two DC-9s had been retired by airlines within six months of the inspections, and a DC-10 was being converted to a cargo aircraft.
It inspected two DC-9s, an Airbus A300, a Boeing 747, a Lockheed L-1011 and a DC-10. Five of the jets had been retired within six months of the inspections, and the DC-10 was inspected as it was being converted to a cargo aircraft.
On the widebody L-1011, the task force's report said there were at least four cracks exposing bare wire in every 1,000 feet of wire tested.
Using 150 miles - the most conservative number of miles of wire that aircraft manufacturers say is on a widebody jet — an L-1011 could have more than 3,100 wiring cracks, USA TODAY calculated.
"This is shocking evidence that reinforces the seriousness of the situation and should be alarming to the traveling public," says Rep. Tillie Fowler, R-Fla., who held a congressional hearing last week on aircraft wiring problems. "Time is of the essence for the FAA to move forward to solve the problems."
She said after last week's hearing that the FAA "has been negligent in its attempt to improve airline wiring and ensure the safety of the traveling public."
The FAA said it would not comment on any details of the task force's report until it is presented this afternoon to a joint FAA-airline industry committee.
At the subcommittee hearing last week, the FAA's Elizabeth Erickson testified that "there are no immediate fleetwide safety problems," but definite wiring-related improvements are needed in maintenance, inspection, training, aircraft design and other areas.
The Air Transport Association, which represents major airlines, had no one available to comment.
Cracks in aircraft wire could result in a short-circuit and a fire.
"Not every crack will cause a problem, but every crack could cause some type of problem, " says Vince Press, a spokesman for Lectromec, which tested wire for the FAA task force.
"A crack could cause the aircraft to receive a spurious signal or result in an electrical noise," he says. "It could also cause a spark or an electrical arc that may not cause any problem at all. Or it could cause a fire that knocks out an aircraft's vital systems."
Of the six aircraft tested by the FAA task force, one old DC-9 had the fewest cracks — 0.50 per 1,000 feet of wire tested.
Experts say that narrowbody jets have 80 to 100 miles of electrical wire. Using the most conservative number — 80 miles — USA TODAY calculated that an old DC-9 could have 200 cracks.
As of last month, U.S. airlines were operating 1,709 jets that are at least 20 years old, according to Christine Francoeur, president of Jet Information Services, which publishes the World Jet Inventory. Worldwide, airlines were operating 3,270 jets that old, she says. http://www.usatoday.com/news/washdc/ncstue09.htm
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Who knows what evil lurks in the hearts of men?
Old jets' wires may be riddled with cracks
By Gary Stoller, USA TODAY
Old airline jets may be flying with thousands of cracks in their electrical wiring, based on a USA TODAY analysis of a new Federal Aviation Administration report.
The report, which is being released Wednesday, was put together by an FAA task force that hired electrical engineers to test wire on six jets, each at least 20 years old.
A Boeing 747, an Airbus A300, a Lockheed L-1011 and two DC-9s had been retired by airlines within six months of the inspections, and a DC-10 was being converted to a cargo aircraft.
It inspected two DC-9s, an Airbus A300, a Boeing 747, a Lockheed L-1011 and a DC-10. Five of the jets had been retired within six months of the inspections, and the DC-10 was inspected as it was being converted to a cargo aircraft.
On the widebody L-1011, the task force's report said there were at least four cracks exposing bare wire in every 1,000 feet of wire tested.
Using 150 miles - the most conservative number of miles of wire that aircraft manufacturers say is on a widebody jet — an L-1011 could have more than 3,100 wiring cracks, USA TODAY calculated.
"This is shocking evidence that reinforces the seriousness of the situation and should be alarming to the traveling public," says Rep. Tillie Fowler, R-Fla., who held a congressional hearing last week on aircraft wiring problems. "Time is of the essence for the FAA to move forward to solve the problems."
She said after last week's hearing that the FAA "has been negligent in its attempt to improve airline wiring and ensure the safety of the traveling public."
The FAA said it would not comment on any details of the task force's report until it is presented this afternoon to a joint FAA-airline industry committee.
At the subcommittee hearing last week, the FAA's Elizabeth Erickson testified that "there are no immediate fleetwide safety problems," but definite wiring-related improvements are needed in maintenance, inspection, training, aircraft design and other areas.
The Air Transport Association, which represents major airlines, had no one available to comment.
Cracks in aircraft wire could result in a short-circuit and a fire.
"Not every crack will cause a problem, but every crack could cause some type of problem, " says Vince Press, a spokesman for Lectromec, which tested wire for the FAA task force.
"A crack could cause the aircraft to receive a spurious signal or result in an electrical noise," he says. "It could also cause a spark or an electrical arc that may not cause any problem at all. Or it could cause a fire that knocks out an aircraft's vital systems."
Of the six aircraft tested by the FAA task force, one old DC-9 had the fewest cracks — 0.50 per 1,000 feet of wire tested.
Experts say that narrowbody jets have 80 to 100 miles of electrical wire. Using the most conservative number — 80 miles — USA TODAY calculated that an old DC-9 could have 200 cracks.
As of last month, U.S. airlines were operating 1,709 jets that are at least 20 years old, according to Christine Francoeur, president of Jet Information Services, which publishes the World Jet Inventory. Worldwide, airlines were operating 3,270 jets that old, she says. http://www.usatoday.com/news/washdc/ncstue09.htm
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Who knows what evil lurks in the hearts of men?
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Some more excellent articles on wiring findings (and more links) at this URL:
http://www.angelfire.com/tn/iasa/old_jets.html
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As a flight-engineer, Throgmorton knew that if he were to pass wind in the Pprune echo chamber, he would likely never hear the end of it
http://www.angelfire.com/tn/iasa/old_jets.html
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As a flight-engineer, Throgmorton knew that if he were to pass wind in the Pprune echo chamber, he would likely never hear the end of it
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This has being doing the rounds for a while now being featured both in English and Australian media. From recollection it was basically to do with the type of plastic coating used, unfortunately the name escapes me, anyway apparently the US NAVY believes it to be such a danger that it wont have any wiring done in this material.
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I think that the coating is called kaptan. It's urea based, has the advantage that it is 33%lighter than conventional plastic insulation, but it has horrendous properties. You must strictly adhere to minimum radius turns in the harness. It will crack otherwise, and, nice one this, if you get an arc the insulation turns into carbon which arcs some more and burns, and arcs some more.... I believe that the RAF lost a couple of Harriers through this a bit back, including one that had been rewired. Nice stuff isn't it.
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Supermunk, you're quite right, the wire that frightened the RAF so much is Kapton. The property of carbon arc tracking was well documented within the services many years ago, although the major airline manufacturers chose to ignore the findings and carried on using the stuff, although belatedly at least Boeing have stopped using it( probably used up all their existing stock).
The exposed wire itself poses no particular worries as if it contacted the airframe the resulting high current would trip the safety devices. The big scare is if a fluid were to be in contact with the bare conductor and either the airframe or another exposed conductor. This sets up a resistive path to earth or between circuits that conducts a current that is within the rating of the fuse or cct breaker. The high current burns the insulation coverting it into carbon, which then continues to burn along the wire, and also burning other wires in the harness or loom.
The absurdity is / was that this undesirable characteristic of Kapton was in use on war planes, which by their very nature are prone to wiring damage.
Yes, we did lose at least two Harriers to suspected fires in the electrical distribution bay in the back end, and they were grounded for several weeks whilst inspection and repairs were carried out.
If treated with kid gloves, tight radii bends avoided and additional protection at potential chafe areas, then it's ok.
It was interesting several months ago on a documentry (can't have been C4 because it was factual and well produced) to witness the denial from the then Boeing spokesman, but there again, the world airliner fleets couldn't be grounded for complete rewires, when the airline industry itself is still regarded to be very safe.
Happy flying .....
The exposed wire itself poses no particular worries as if it contacted the airframe the resulting high current would trip the safety devices. The big scare is if a fluid were to be in contact with the bare conductor and either the airframe or another exposed conductor. This sets up a resistive path to earth or between circuits that conducts a current that is within the rating of the fuse or cct breaker. The high current burns the insulation coverting it into carbon, which then continues to burn along the wire, and also burning other wires in the harness or loom.
The absurdity is / was that this undesirable characteristic of Kapton was in use on war planes, which by their very nature are prone to wiring damage.
Yes, we did lose at least two Harriers to suspected fires in the electrical distribution bay in the back end, and they were grounded for several weeks whilst inspection and repairs were carried out.
If treated with kid gloves, tight radii bends avoided and additional protection at potential chafe areas, then it's ok.
It was interesting several months ago on a documentry (can't have been C4 because it was factual and well produced) to witness the denial from the then Boeing spokesman, but there again, the world airliner fleets couldn't be grounded for complete rewires, when the airline industry itself is still regarded to be very safe.
Happy flying .....
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I seem to recall that the US Navy lost a couple of F16's and suspected Kapton insulated wiring. Later investigation by the Navy highlighted the nasty little habits (arc tracking, cracking, hydrolitic etc) of this stuff. Subsequently the F16's were rewired or scrapped. Off course there is Swissair Flt 111. I don't recall seeing final conclusions on this crash, but there was certainly strong evidence that a wiring insulation failure above the cockpit was to blame.
The real problem is that a large portion of the worlds passenger jets still use this stuff. Boeing stopped using it in '92, but I understand that Airbus still use it. There is no way that it will ever be replaced in existing aircraft due to the cost. It would cost less to replace the planes than to rewire them, and who would pay? It would bankrupt ALL major airlines, and manufaturers, and the impact on the world economy would be disasterous.
Cheers,
Feeton
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Once I was VERY good, now I'm very good, once!
The real problem is that a large portion of the worlds passenger jets still use this stuff. Boeing stopped using it in '92, but I understand that Airbus still use it. There is no way that it will ever be replaced in existing aircraft due to the cost. It would cost less to replace the planes than to rewire them, and who would pay? It would bankrupt ALL major airlines, and manufaturers, and the impact on the world economy would be disasterous.
Cheers,
Feeton
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Once I was VERY good, now I'm very good, once!
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It all depends on the cable type. BMS 13-13 (used in 707/720, amonst others) could crack lengthwise.
BMS 13-51 and other thin-walled cables can also lose the outer coating without losing the integrity of the inner insulator (which is copper coloured - the uninitiated are unaware that most aircraft cable is nickel plated copper).
The inherent risks associated with Kapton are well known.
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Bus429 - the pilot's pal!
BMS 13-51 and other thin-walled cables can also lose the outer coating without losing the integrity of the inner insulator (which is copper coloured - the uninitiated are unaware that most aircraft cable is nickel plated copper).
The inherent risks associated with Kapton are well known.
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Bus429 - the pilot's pal!
