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B.A.Longhaual a/c multiple lightning strikes.

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B.A.Longhaual a/c multiple lightning strikes.

Old 23rd Jul 2007, 01:40
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Actually I think the system Mungo man is revering to is a E135/E145 which is a quite new plane. The E170-195 series which is well ahead of it's time has the same option, also will paint areas of turbulence unfortunately that function does not detect CAT.
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Old 23rd Jul 2007, 03:34
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Storm Scopes

Many higher performance General Aviation airplanes beginning in the eighties used to be equipped with a cheaper alternative to weather radars - Storm Scopes. Unlike our radars which detect wet precipitation, storm scopes worked more like ADF's by tracking areas of electrical discharge in clouds. Some airplanes were even retro-fitted with both storm scopes & weather radars by extravagent owners. To identify areas of high electrical activity (and hence likelihood of lightning strikes), Storm Scopes are probably better than weather radars. In essence however, both of these types of equipment serve to identify where the storm is, and hence their avoidance - not to encourage penetration of it.

As to the effect of lighting strikes on a person, much has already been said. The Physics description of this is a "Faraday Cage" - where the electrical current is conducted around the metallic exterior of the vehicle, not the inside, thereby protecting the occupants.

I once had a lighting strike on a B777 passing 13000' during descent through "green" radar returns. It struck on the right side just behind the radome. The First Officer was none the worse for it, as was the airplane. Up till that time, i was privately skeptical about how a highly electronic airplane like the 777 would hold up in a lightning strike - as it turned out, there was not even a flicker in any of the instruments EFIS/FMC/AFDS/COMMS/RADAR/stby compass.... nothing. Once on the ground i discovered where it struck and the only thing was a couple of burned out static wicks. I've been a fan ever since.
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Old 23rd Jul 2007, 10:38
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Lightning sensors (Stormscope) were integrated into the radar display and were specified as original equipment on Jetstream 41 aircraft that were delivered to BRAL/Loganair.

The reasoning was that these aircraft would be spending their flying lives at or below FL250, where there is a greater risk of strikes and were specified, not by "extravagent owners", as gengis put it, but as a cheap addition to assist crews avoid both lightning and cb activity, which are not neccessarily co-located. Pilots liked it too.

The commercial payoff was that there was a significant reduction in reported lightning strikes on the J41 compared to the ATP which was not equipped with sensors; thus less engineering time was spent on lightning strikes and their aftermath.

Because of this good experience, a similar fit was ordered on the EMB145 although Embraer took a little time to get it installed.

It was a cost and safety effective tool as far as we were concerned. Bit like the talking checklist really, but that's another story.
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Old 23rd Jul 2007, 11:11
  #24 (permalink)  
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Take a seat for some testing - any volunteers?

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Old 23rd Jul 2007, 16:15
  #25 (permalink)  

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Originally Posted by bereboot
Actually I remember a BA 757 operating into AMS , where the FO was seriously injured with burning wounds on his arm , which was resting on the windowframe when it got struck by lightning.
Must been asome 5 years ago , can anybody fill me in on this ??
AAIB link
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Old 23rd Jul 2007, 19:57
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another plasma ball long ago in a 707

Adding to the plasma ball in the PAX cabin.... ages ago when I was a lad I was in a 707 from HNL to SEA when we were hit. Had a lovely plasma ball dance its way along the seat tracks the length of the cabin. I of course thought it was the neatest thing in the world but it was a minority opinion.
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Old 23rd Jul 2007, 20:13
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Towrope's story reminds me of my dear old Mum who relates the tale of a plasma ball in a 707 on the way back from Bermuda many years ago. She says it took several seconds to travel from front to rear and left a very interesting smell! The hairs on her arms apparently took the rest of the flight to lay back down. I was oblivious to it all, asleep in my crib! (so she tells me)
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Old 23rd Jul 2007, 21:24
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As cabin crew, I witnessed a similar event in the cabin of a B757 many years ago. In rather turbulent conditions, a ball of lightning flew down the entire length of the aisle from front to back and seemed to exit via the R4 door. Pax were cr@pping themselves. An attractive young female asked if I would "hold her hand if we were going to crash," to which I reassuringly replied "sweetheart, if we we're going to crash you'd be holding my knob not my hand!"
On a separate flight, again on a B757, the left wing was struck by lightning during the latter stages of the descent. Sounded like the No.1 engine had exploded! Uneventful landing followed, without the Captain even making an explanatory PA to the rather concerned passengers.
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Old 23rd Jul 2007, 23:40
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.....back of a Canberra. I was struck off the Scillies.....
I'm not a doctor, but that sounds painful to me
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Old 24th Jul 2007, 00:19
  #30 (permalink)  
 
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Originally Posted by Mungo Man
No real way to show lightning... apart from the LSS (Lightning Sensor System) on my aircraft which is independent from the Wx radar, and shows lightning within 100nm radius.
Our Diamond DA42 has a Storm Scope which does a great job of showing you where the lightning is - useful on a carbon fibre composite aeroplane! By no stretch of the imagination could it be described as an "extravagance"
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Old 24th Jul 2007, 14:42
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how does this work in composite a/c

modern aircraft are constructed (bonded) in such a way that allows the massive electrical loads experienced in a lightning strike to be safely dispersed via static discharge wicks which are usually located near the wingtips and the vertical stabilizer.
Probably a stupid question: I assume "bonded" refers to composite materials. How do the modern composite designs deal with this? My experience with composites is 15 years old and was very limited, but IIRC, the composite components do not conduct electricity that well, and might not take the heat from an impact as well as metal (could be wrong of course). While big portions are still metal, aren't some only composite? I am sure they found a solution (or this is not a problem)....but how?
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Old 24th Jul 2007, 15:00
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Originally Posted by FlyingConsultant
I assume "bonded" refers to composite materials.
It doesn't actually. It refers to the (usually flexible) metal strips that electrically connect moving parts (like controls surfaces and flaps, or doors) and removable parts (think tail cone, for instance) to the main aircraft structure. If those strips are absent or defective, the current from a lightning strike can take highly undesirable paths, such as via actuators or control rods.
As to the behaviour of composite materials during lightning strikes, I have no idea either. I hope somebody else has some answers on this. I would have thought the "bulk" electrical resistance of composite materials would be a lot higher than that of aluminium.

Last edited by ChristiaanJ; 24th Jul 2007 at 15:00. Reason: spelling
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Old 24th Jul 2007, 16:27
  #33 (permalink)  

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Looking at the 777 that was whacked on the left engine D duct, the composites don't fair too well! In this case the translating sleeve has got to be replaced and one of the fan cowls requires extensive repair.
One wonders how the 787 will cope, or indeed the 350 with its 'plastic' wing.
The D duct has several holes where the composite filaments have shattered with the resin being destroyed, as the lightning passed through and out of the the duct it has also delaminated the trailing edge. It appears that the 'bolt' passed from left to right and exited (with associated damage!) through the right wing damaging the outb'd aileron and tip.
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Old 24th Jul 2007, 17:09
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After yesterdays terrible weather BA have at least 11 aircraft on the ground with multiple lightning strikes
ouch ! Any significant damages ?
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Old 25th Jul 2007, 01:44
  #35 (permalink)  

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More ball lightning

I was in the rather smelly hold of a C130 on approach to Deci (Sardinia) which was struck. There was a tremendous bang and a ball of lightning appeared and headed off to the ramp at the rear, where it disappeared.

The lower VHF blade antenna had been blown completely off, with other damage elsewhere on the outer skin.
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Old 25th Jul 2007, 06:44
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30+ years at it from Electras through to 747/400s and only twice was i shaken up badly..both strikes..one on descent into ATH..rhs of 747 struck between R1 and R2 doors..exactly where i was working..sounded as if we had been machine gunned and when the guys checked after landing, there were about 25 holes along the fuselage, even looked like large bullet holes.
Other was NAN/HNL.707/138..just the one hit... rhs again but loudest thing I've ever heard..the shakes and sweats didn't start for a couple of minutes but they lasted a bit longer.And no marks on the fuselage!
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Old 25th Jul 2007, 16:15
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Evening Star,
A couple of interesting points included in that AAIB report:
1) BA appear to fly the 757 single crew with no pax, and
2) The Commander had 234 flying hours in the 90 days previous to the incident. Who says BA pilots don't earn their keep?
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Old 26th Jul 2007, 15:50
  #38 (permalink)  
 
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the composites don't fair too well! In this case the translating sleeve has got to be replaced and one of the fan cowls requires extensive repair.
.......
The D duct has several holes where the composite filaments have shattered with the resin being destroyed, as the lightning passed through and out of the the duct it has also delaminated the trailing edge. It appears that the 'bolt' passed from left to right and exited (with associated damage!) through the right wing damaging the outb'd aileron and tip.
I have to admit I cannot follow this completely, but the description does not surprise me. From what I remember (could be wrong with more modern composites) these materials do not conduct electricity very well. One could conclude that they are less likely to be hit (no idea but I would guess that's true), but the problem is that there is still plenty of metal in and around the stuff. So lightning will ultimately find the metal - but on its way it will heat up the composites very rapidly. They don't take that too well. In addition to the bonding agent, depending on thje composit, some have air and gas bubbles, and in some cases water embedded, which I guess would explovely expand, leading to local delamination. Oops

On the other hand, it's such an obvious question that somebody must have thought about it, so I assume (stupid me) that there is nothing unsafe here. Just very expensive to repair.
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Old 26th Jul 2007, 16:28
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On the other hand, it's such an obvious question that somebody must have thought about it, so I assume (stupid me) that there is nothing unsafe here. Just very expensive to repair.
The composites are made from carbon filaments and IIRC the structure also has a fine mesh bonded in to it. The carbon will conduct at the +ve here.
In the case of the D duct it looks like one of the major stikes hit a panel screw .....and welded it in! then tracked fore and aft exiting along the trailing edge of the duct.
Nothing too unsafe and yes very expensive!
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Old 26th Jul 2007, 19:46
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Speakin as an engineer I have seen many aircraft with lightning strikes, but the worst damage was a line of 13 burnt rivets across the L1 door. The reason aircraft get grounded is that you must inspect the aircraft which requires a high lift, and usually there is more than one aircraft hit, and only one high lift.
The only emergency I witnessed caused by lightning was a DBA F100 which was hit at rotation. The lightning knocked out BOTH engine oil pressure transmitters. So the crew got two ECAM warnings, each one warning of low oil pressure and recommending engine shut down. Being quick thinking, after shutting down the left engine, they decided to keep the right engine running for a quick circuit!
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