spr773
Topic Author
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What Happens During A Lightning Strike

Fri Jun 20, 2008 3:03 am

Hello,
I just flew on an 9W 738 and we passed through a thunderstorm and there were lots of clouds which is quite common in this part of the world at this time of the year (Monsoons in India). My question is that if lightning strikes how is it taken care of in a plane ? Ideally since there is no least resistance path to the "Ground" lightning would not strike , but even then if an aircraft does come in the path of lightning what happens ?  raincloud 
 
BP1
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RE: What Happens During A Lightning Strike

Fri Jun 20, 2008 3:04 am

Do you mean a static discharge?

BP1
"First To Fly The A-380" / 26 October 2007 SYD-SIN Inaugural
 
spr773
Topic Author
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RE: What Happens During A Lightning Strike

Fri Jun 20, 2008 3:10 am

Yes static discharge...!!!
 
WingedMigrator
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RE: What Happens During A Lightning Strike

Fri Jun 20, 2008 3:20 am



Quoting SPR773 (Thread starter):
if lightning strikes how is it taken care of in a plane ? Ideally since there is no least resistance path to the "Ground" lightning would not strike , but even then if an aircraft does come in the path of lightning what happens ?

The aircraft usually triggers the lightning. Sharp edges and tips will concentrate the ambient electric field to the point of breakdown (ionization of the air), setting off the lightning discharge. The aircraft does not absorb charge, and simply conducts the lightning current from cloud to cloud or cloud to ground. The current density can locally exceed the capability of the airplane structure to conduct it, causing localized heating and damage. Lightning also creates a strong electromagnetic pulse that can briefly interfere with the operation of avionics and power systems.
 
pilotpip
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RE: What Happens During A Lightning Strike

Fri Jun 20, 2008 3:28 am

Got struck last week, about six inches from my butt right below the window.

Bright flash, deafening noise. Captain and I look at each other and think "WTF!?"

Look at the MFD, PFD, and EICAS, make sure everything is still working.

Call back to the F/A, make sure they're ok.

Keep flying.

Report to MX, do super post-flight walkaround. See small burn mark about 7 inches below my window, and a hole in the flap fairing where it exited. MX does their thing. We go to hotel.

Fill out lightning strike report.
DMI
 
spr773
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RE: What Happens During A Lightning Strike

Fri Jun 20, 2008 4:25 am

PilotIP...your description of the strike sounds scary....  scared  ....
just adding one more question....is the problem of turbulence less as the aircraft size increases...I mean from a passengers point of view....I flew in an ATR in a thunderstorm and man was it scary with lots of turbulence....however when I flew a 777 it was fairly less....or does it really depend on the clouds and external conditions ?
 
tdscanuck
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RE: What Happens During A Lightning Strike

Fri Jun 20, 2008 5:17 am



Quoting SPR773 (Thread starter):
My question is that if lightning strikes how is it taken care of in a plane ?

It happens, on average, about once per year per airplane. Most of the time, it does a small amount of damage (a few burned rivets, sometimes a blow diverter strip or static discharge wick) that can be deferred or repaired on an overnight, and you go about your day.

Quoting SPR773 (Thread starter):
Ideally since there is no least resistance path to the "Ground" lightning would not strike

Actually, an aluminum airplane makes a very nice lightning rod and low-resistance path. Lightning will preferentially strike an airplane if there's one around.

Quoting SPR773 (Reply 2):
Yes static discharge...!!!

Not the same thing. Static discharge is the release of static charge that builds up on the airplane due to motion through the air. Lightning is conduction of an external current through the airplane...very different effect.

Tom.
 
kaitak
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RE: What Happens During A Lightning Strike

Fri Jun 20, 2008 5:25 am

The lightning gets very upset, contacts its union, then after thunderous argument, there's lots of clapping and banging and there's a vote; it's a highly charged atmosphere ... Finally, they sit around and mediate, the dark clouds disperse and finally, blue skies again.

I'm sorry, I just couldn't resist ...
 
flymad
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RE: What Happens During A Lightning Strike

Fri Jun 20, 2008 6:00 am



Quoting Kaitak (Reply 7):
The lightning gets very upset, contacts its union, then after thunderous argument, there's lots of clapping and banging and there's a vote; it's a highly charged atmosphere ... Finally, they sit around and mediate, the dark clouds disperse and finally, blue skies again.

I'm sorry, I just couldn't resist ...

 rotfl   rotfl   thumbsup  Classic, absolutely brilliant!!
 
aznmadsci
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RE: What Happens During A Lightning Strike

Fri Jun 20, 2008 6:08 am



Quoting Kaitak (Reply 7):
The lightning gets very upset, contacts its union, then after thunderous argument, there's lots of clapping and banging and there's a vote; it's a highly charged atmosphere ... Finally, they sit around and mediate, the dark clouds disperse and finally, blue skies again.

Where does the flashing take place?  knockout 
The journey of life is not based on the accomplishments, but the experience.
 
isitsafenow
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RE: What Happens During A Lightning Strike

Fri Jun 20, 2008 12:16 pm



Quoting Kaitak (Reply 7):

Yeah, thats happens alot here in the USA, doesn't it?
By the way, well done!
safe  highfive 
If two people agree on EVERYTHING, then one isn't necessary.
 
albird87
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RE: What Happens During A Lightning Strike

Fri Jun 20, 2008 12:33 pm



Quoting SPR773 (Reply 5):
I flew in an ATR in a thunderstorm and man was it scary with lots of turbulence....however when I flew a 777 it was fairly less....or does it really depend on the clouds and external conditions ?

I agree! I flew into IAD once in september on BA from LHR in a 744 and there was some wikid storms north of the field that we had to go through and we were thrown around! i mean this 744 was going from side to side and up and down! People all around me were reaching for the sick bags and i was enjoying it! after 20 mins though of this I was getting a bit queezy myself! thankfully we were out of it and soon on the ground where a lot of people were thankful to be back on the ground! Now I was thinking to myself thank god i wasnt in a 737 going through that storm!
 
art
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RE: What Happens During A Lightning Strike

Fri Jun 20, 2008 12:59 pm



Quoting SPR773 (Thread starter):
My question is that if lightning strikes how is it taken care of in a plane ?

Got struck coming into Rome once. The way it was taken care of within the plane was by a lot of screaming then the rosaries came out and the praying started in earnest. Smile
 
ptcflyer
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RE: What Happens During A Lightning Strike

Fri Jun 20, 2008 1:42 pm

I was on a CO DC10 flight 15 from EWR - HNL in 1988. We had an electrical discharge upon departure climbout. Loud boom/thud with instant flash. Must admit, the 250 passengers all skipped a hearatbeat or two while we tried to figure out what this meant or what was going to happen next. The silence in the plane was notable.

After a few minutes of silence, the pilot came on and explained the situation. Said that all instruments were fine. We continued to HNL.

In HNL, the plane was inspected completely with bright lights before we reboarded the same plane for SYD.

Not sure where the strike happened, but he pilot jokingly mentioned he "ducked".
 
co777er
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RE: What Happens During A Lightning Strike

Fri Jun 20, 2008 1:49 pm



Quoting Albird87 (Reply 11):
Quoting SPR773 (Reply 5):
I flew in an ATR in a thunderstorm and man was it scary with lots of turbulence....however when I flew a 777 it was fairly less....or does it really depend on the clouds and external conditions ?

I agree! I flew into IAD once in september on BA from LHR in a 744 and there was some wikid storms north of the field that we had to go through and we were thrown around! i mean this 744 was going from side to side and up and down! People all around me were reaching for the sick bags and i was enjoying it! after 20 mins though of this I was getting a bit queezy myself! thankfully we were out of it and soon on the ground where a lot of people were thankful to be back on the ground! Now I was thinking to myself thank god i wasnt in a 737 going through that storm!

I was on a CO 777 from LGW-IAH two years back, and one of those sudden intense summer storms developed over the airport. We executed holding pattern and the pilot came on the intercom and said that the fuel level was getting a bit low, and that we would have to either go to Ellington field (HOU isn't an option b/c of size, weight etc) and be bussed up or, fly through the storm. Well, they chose to fly through the middle of that dang storm, and the 777 was hopping all over the place. Left, down, right, down, up, down, right... Overhead bins were opening up, and we hit some of those "air pockets" (I know they don't exist, but for lack of better terms). We were in BF, and there were two flight attendants that at one point had their hands on the roof of the cabin near the forward doors, body completely in the air. I couldn't believe that they would get up and close the overhead bins and jeopardize their safety. I mean, after all, the 777 bins are tilted so that it would be very hard for a bag/suitcase to fall down. After all the excitement, the PIC landed perfectly. And best of all, no customs line upon arrival!
 
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NWAESC
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RE: What Happens During A Lightning Strike

Fri Jun 20, 2008 1:56 pm



Quoting Albird87 (Reply 11):
People all around me were reaching for the sick bags and i was enjoying it!

It's always interesting to me how differently people react to the same set of circumstances!

I was on a particularly rough flight once (Dash-8 going RAP-DEN), and saw or heard all of the following occur simultaneously around me:

A. Vomiting

B. Screaming

C. Praying

D. Staring straight ahead, with a death grip on the arm rest

E. Sleeping

F. People excited as hell, cheering and clapping
"Nothing ever happens here, " I said. "I just wait."
 
nema
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RE: What Happens During A Lightning Strike

Fri Jun 20, 2008 4:09 pm



Quoting Tdscanuck (Reply 6):
It happens, on average, about once per year per airplane. Most of the time, it does a small amount of damage (a few burned rivets, sometimes a blow diverter strip or static discharge wick) that can be deferred or repaired on an overnight, and you go about your day.

I wonder if anyone looks for this damage immediately after the flight or if it is found later at a service interval? I had just one occasion on a A330 when a loud bang shook us all when stacking above YYZ. The bang was so loud I first thought that an engine had exploded, the cabin went very quite but very quickly you realise that everything just carried on as normal but....how do you find that possibly damaged 'Hit Point' that may be quite small on such a large aircraft?
There isnt really a dark side to the moon, as a matter of fact its all dark!
 
avt007
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RE: What Happens During A Lightning Strike

Fri Jun 20, 2008 5:10 pm



Quoting NEMA (Reply 16):
....how do you find that possibly damaged 'Hit Point' that may be quite small on such a large aircraft?

It's not that hard- look on the nose, that's where the vast majority of lightnin bolts enter the aircraft. Usually the hard part is deciding if it's fresh damage, or an old strike. The exit points are usually the tail, but sometimes the wingtips as well. Basically, look at all the pointy bits, that's where the lightning goes in and out.
 
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fr8mech
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RE: What Happens During A Lightning Strike

Fri Jun 20, 2008 5:31 pm



Quoting NEMA (Reply 16):
wonder if anyone looks for this damage immediately after the flight or if it is found later at a service interval?

If the flight crew reports a lightning strike, the inspection is conducted before further flight.

I've seen everything from little burn marks on fasteners to the trailing edge of entire flight controls blown-out. The favorite exit point for lightning is the trailing edge of a flight control or, especially on the B767, the trailing edge of the T/R halves.
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DocLightning
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RE: What Happens During A Lightning Strike

Fri Jun 20, 2008 7:36 pm



Quoting Kaitak (Reply 7):
The lightning gets very upset, contacts its union, then after thunderous argument, there's lots of clapping and banging and there's a vote; it's a highly charged atmosphere ... Finally, they sit around and mediate, the dark clouds disperse and finally, blue skies again.

I'm sorry, I just couldn't resist ...

 bigthumbsup   rotfl  Brilliant.

A conductor usually conducts a strong charge more around its periphery. This is because all the negative charges shove each-other apart and so the best way to do that is to head to the outer shell. So the lightning restricts itself to the outer skin and then goes about its business. Only the entry and exit points are typically damaged.
-Doc Lightning-

"The sky calls to us. If we do not destroy ourselves, we will one day venture to the stars."
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KELPkid
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RE: What Happens During A Lightning Strike

Fri Jun 20, 2008 8:23 pm



Quoting Tdscanuck (Reply 6):
Not the same thing. Static discharge is the release of static charge that builds up on the airplane due to motion through the air.

Correct. Excessive static charge on the airframe can lead to a condition known as Saint Elmo's Fire (not to be confused with cheesy 1980's American movies Big grin ), where the charged particles in and around the airframe start constantly discharging into the surrounding air. Static wicks are supposed to dissipate this type of static charge.
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airbalticfan
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RE: What Happens During A Lightning Strike

Sat Jun 21, 2008 12:48 am

I am glad we all can laugh about it now but when it happens it is scary as hell!Safe flights to all of you guys!
 
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Starlionblue
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RE: What Happens During A Lightning Strike

Sat Jun 21, 2008 12:53 am



Quoting SPR773 (Reply 5):
just adding one more question....is the problem of turbulence less as the aircraft size increases...I mean from a passengers point of view....I flew in an ATR in a thunderstorm and man was it scary with lots of turbulence....however when I flew a 777 it was fairly less....or does it really depend on the clouds and external conditions ?

Larger aircraft have more or less the same proportional "sail area" (bigger wings, fuse and empennage) so they are susceptible to turbulence just like smaller ones. However they do mass more. Newton's laws of motion dictate that it takes more energy to get objects with a higher mass moving. Consequently larger aircraft tend to feel more stable.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
tdscanuck
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RE: What Happens During A Lightning Strike

Sat Jun 21, 2008 1:03 am



Quoting Fr8Mech (Reply 18):
The favorite exit point for lightning is the trailing edge of a flight control or, especially on the B767, the trailing edge of the T/R halves.

737 too...pain in the a$$. Horizontal stabilizer diverter strips are another favorite spot.

Tom.
 
WingedMigrator
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RE: What Happens During A Lightning Strike

Sat Jun 21, 2008 3:29 am



Quoting Starlionblue (Reply 22):
However they do mass more. Newton's laws of motion dictate that it takes more energy to get objects with a higher mass moving. Consequently larger aircraft tend to feel more stable.

This may be true, but don't use Newton's laws to prove it.

It takes more force to achieve the same disturbance acceleration--the force is proportional to mass (Newton's 3rd law). The disturbance force is also proportional to wing area. And wing area is again proportional to mass... ergo: Newton's laws predict the same stability for a small aircraft as for a big aircraft.  Smile

It may have more to do with wing loading... the more load per unit area of wing, the less disturbance.
 
jimbobjoe
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RE: What Happens During A Lightning Strike

Sat Jun 21, 2008 6:43 am



Quoting WingedMigrator (Reply 24):
It may have more to do with wing loading... the more load per unit area of wing, the less disturbance.

I have heard that elsewhere on this board. For that reason, one of the least suscepitble aircraft to turbulence is the (relatively) small-winged MD-80.
 
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HAWK21M
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RE: What Happens During A Lightning Strike

Sat Jun 21, 2008 2:47 pm





Lightening strike Inspections are in two parts.....If Faults are detected in the 1st part,more detailed Inspections are called for in Part 2.

During a strike the Aircraft acts as the conducting medium,there will be an entry & exit point.



regds
MEL
I may not win often, but I damn well never lose!!! ;)
 
josekmlb
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RE: What Happens During A Lightning Strike

Tue Jun 24, 2008 7:44 am

Well a few years back we pushed out a B737-800 (Delta) from the gate and it was overcast but not any signs of lightning, then out of sky came a strike and hit the tail of the a/c at the same time two of my ramp agents were taking the tow bar off the nose and somehow the lightning traveled threw the tail and out the nose of the a/c and struck them both and blew up the headset. It fried the cockpits controls I mean everything in it.

I hear that it is safer for the plane to be struck in flight then on the ground, don't know if its really true or not but thats the only time I saw an a/c get struck by lightning.

By the way the two ramp agents went to the er and were fine later after treatment and returned to work.
 
Dougloid
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RE: What Happens During A Lightning Strike

Tue Jun 24, 2008 1:12 pm

Certainly nothing to be casual about-a lightning strike can cause a lot of damage. I worked on a Merlin one time, the right hand prop took a lightning strike and the slag from the blade hit the windshield and damaged it to the extent it had to be replaced.

The current went through the engine, out the tailcone and into the structure and departed through the tail static wick.

There's no repair manual procedure for a lightning strike inspection so what I did was pulled the engine off the wing, completely disassembled it and demagnetized all the smaller ferrous parts by passing them through the coil on our magnaflux machine. The engine mount was heavily magnetized and we got an industrial inspection company to come out and pretend they were demagnetizing something they'd just tested.

There were several bearings that were burnt as the current passed through them, They wouldn't have survived a great deal of further use.

The airframe people followed the track of the current, fixing the burns where it met some resistance.
If you believe in coincidence, you haven't looked close enough-Joe Leaphorn
 
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HAWK21M
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RE: What Happens During A Lightning Strike

Tue Jun 24, 2008 3:08 pm



Damage caused by Lightening on a B737.

regds
MEL
I may not win often, but I damn well never lose!!! ;)

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