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Old 5th July 2009, 08:07 AM   #1
Ipanema is offline Ipanema  Malaysia
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Default Loudspeaker magnet and aircraft safety

I just bought a pair of 8" Pioneer and 2 pairs of 5.25" Vifa coaxial autosound from Part Express. The problem is these loudspeakers does not pass the check-in scanner when I left LAX and Taipei airport back to Malaysia. Both airports authority searched my bag high and low suspecting something dangerous that I might be carying. They warn me that these speaker magnet might cause aircraft safety problem inside the plane cargo. But I don't understand how these magnet able to pose any threat to aircraft safety. Anyone have similar experience?
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Old 5th July 2009, 12:53 PM   #2
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http://www.arnoldmagnetics.com/mtc/FAQ.htm Scroll down to the bottom of the page to see the warning about shipping magnets on aircraft.

There are many regulations that cover what can be carried aboard aircraft and the packaging requirements for those items. They get fussy about things that can explode - or cause fires - interfere with navigation or communications equipment etc.

Magnetic materials can be shipped aboard aircraft but they have to be clearly marked as being magnetic - and then they get placed in a special storage area of the aircraft.
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Old 5th July 2009, 01:51 PM   #3
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when I went to the US, I bought a pair of tang band 6.5" subs and a pair of HiVi 3 inchers. didn't have any trouble with the airline going back home. must have been lucky.
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Old 5th July 2009, 02:14 PM   #4
soongsc is offline soongsc  Taiwan
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I've had some deliveries where they were VERY well wrapped in metal per requirements depending on type of aircraft so that the magnetic field cannot be detected.
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Old 5th July 2009, 03:44 PM   #5
Ipanema is offline Ipanema  Malaysia
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Quote:
field of more than 0.00525 gauss measured at 4.5 meters (15 feet)
THanks for the info. How to estimate the field strength quoted above e.g magnet size? and how to get around this rule? I still have lot's of drivers wishlist from US.
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Old 5th July 2009, 06:21 PM   #6
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I remember reading about this in an OLD book about loudspeakers. The stray magnetic field from loudspeakers could affect the on-board magnetic compass. The book I read sights a case where a shipment of speakers lead to the airplane being ~500miles off course!
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Old 5th July 2009, 07:00 PM   #7
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Quote:
Originally posted by Ipanema


THanks for the info. How to estimate the field strength quoted above e.g magnet size? and how to get around this rule? I still have lot's of drivers wishlist from US.
When magnets are shipped via air freight the manufacturer has usually worked out a method to reduce the magnetic fields to levels that meet safety requirements. There are ways that the magnets can be arranged that will help to reduce the magnetic field (back to back for example), there is shielding that can be used (like a metal can), or they can be put into a shielded cargo bay or shielded cargo container.

Aircraft that carry freight usually have some area’s in them that have been certified to carry materials that are considered hazardous (explosive, flammable, radioactive, magnetic, etc.) so getting the item’s shipped via approved carriers is less involved than getting them loaded onto a passenger aircraft.

Most of the large aircraft today use non-magnetic electronic compasses and GPS anyway – but magnetic compasses are still common on smaller aircraft.
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Old 6th July 2009, 01:52 PM   #8
Ipanema is offline Ipanema  Malaysia
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Solution?
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Old 6th July 2009, 02:37 PM   #9
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Quote:
Originally posted by Ipanema
Solution?
If you have the drivers shipped via air freight from a supply house such as Parts Express (or others) they are familiar with the shipping requirements and pack and label things accordingly. Difficulties arise when passengers try to bring things aboard commercial flights that don't have storage compartments for hazardous materials.

So - order your parts from a source that can provide the proper shipping and no problems - be happy!
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Old 6th July 2009, 07:30 PM   #10
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Typically packing two speakers together with their magnets facing away from each other will get them to pass the requirements for air shipping. You can test using a magnetic compass. The compass needle can't be deflected when it is some distance away from the package. You'll have to look up the distance. If you have speakers with center magnets (like Alnico or a lot of neo speakers), you shouldn't have a problem. Actually taking them on the plane with you is an entirely different matter though.
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