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AVIATION => Operational => Topic started by: himey on July 09, 2008, 01:46:47 PM

Title: fusible plugs
Post by: himey on July 09, 2008, 01:46:47 PM

hey guys me again lol
anyone got a drawing i can use in powerpoint of a aircraft wheel with a fusible plug got stuck with writting a undercarriage lecture cheers

Title: fusible plugs
Post by: John Webb on July 09, 2008, 06:59:41 PM

I'm intrigued! Why are aircraft wheels fitted with 'fusible plugs', please? The only such plugs I've ever come across were in boilers, static and railway locos, to protect them from too low a water level for safe operation.

Title: fusible plugs
Post by: Fireguy1230 on July 09, 2008, 10:44:10 PM

Hi John

 Fusible plugs are fitted to aircraft undercarriages and serve to vent the pressure within the tyres in the event of overheating. If they didn't have them there would be a danger of the wheel exploding due to the increased pressure within it when it gets excessively hot.

All the plug does is blow off (at around 150c if my memory serves me correct) and allows the tyre to deflate, thus reducing the risk of it going bang.

Title: fusible plugs
Post by: Yeebsy on July 09, 2008, 10:48:25 PM

Edit.

Fireguy beat me to it. Long night FG?

Title: fusible plugs
Post by: Fireguy1230 on July 10, 2008, 12:55:38 AM

Very long!

 Gotta love watchroom through the night. And we've had the Sky telly disconnected, just to really make the experience a painful one.

Title: fusible plugs
Post by: John Webb on July 10, 2008, 10:17:22 AM

Thanks - not dissimilar to the boiler plugs then - gives protection against overheating.

Title: fusible plugs
Post by: Yeebsy on July 10, 2008, 02:46:55 PM

I wouldn't say they 'give protection against overheating' as they have nothing to do with stopping the assemblies from overheating. They just stop the wheel assembly from exploding if they temperatures get excessive during a fire situation.

Title: fusible plugs
Post by: TallyHo on July 10, 2008, 10:57:29 PM

You mean like this?

http://www.youtube.com/watch?v=VRD-_glEThs

Title: fusible plugs
Post by: Yeebsy on July 11, 2008, 12:06:06 AM

Thats the one I was looking for but couldn't find, nice one. That shows what happens without or wrong fusible plugs installed. Thats when the French guys found out adrenalin was brown. :)

Title: fusible plugs
Post by: himey on July 14, 2008, 02:31:03 PM

heres the proper statement lol on fusible plugs

.  In order to overcome dangerous pressure build up when the wheels are hot, fusible plugs are fitted.  These are small bolts that have a small hole drilled through the centre.  This hole is filled with a low melting point metal (normally 150oC – 250oC).  If the wheels get excessively hot the low melting point metal melts and allows Nitrogen to escape thus venting excessive pressure.  The escaping Nitrogen is directed towards the brakes offering some cooling effect.  The effect of the continuous landing and taking off can lead to the build up of rubber dust which has an ignition temperature of around 250oC – 350oC.

Title: fusible plugs
Post by: BAAfiery on August 08, 2008, 11:19:58 PM

I've been under a 747F when all the plugs went on the starboard main u/c. I don't remember if they went bang but it was very disconcerting when the a/c starts coming down on one side!