Lightning Strikes
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War story from my old mountain flying instructor who had lightning strike in 206 while on approach to land. Caused engine flameout but luckily he had auto re-ignite turned on which saved the day.
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212 North Sea (Norwegian?) if memory correct required scrapping of blades, head, MGB, engines, combining gear box, and drive line back to tail rotor and including tail rotor due arcing damage on components. Expensiiiive.
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Once in a S61, which scrapped all five main blades, and once in a 332L which had similar results to those experienced by Sailor Vee, with the added complication of totally sh
ing the MGB. Didn't notice anything much until we were on the ground and the engineers's eyes popped.
Now fly medern Eurocopter types with carbon blades and I definately wouldn't want a strike on one of those. A few years ago in the uk a glider took a strike and the wing exploded, very similar construction and materials.
ing the MGB. Didn't notice anything much until we were on the ground and the engineers's eyes popped.Now fly medern Eurocopter types with carbon blades and I definately wouldn't want a strike on one of those. A few years ago in the uk a glider took a strike and the wing exploded, very similar construction and materials.
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An aircraft certified to the latest regs is much safer. Composite blades are not a problem.
29.610 - Lightning protection. This is the basic airframe lightning protection regulation, which requires that the rotorcraft be able to sustain a lightning strike without catastrophic damage.
*
29.954 - Fuel System Lightning Protection. This regulation requires that fuel tanks and systems be free of ignition sources such as electrical arcs and sparks due to direct or swept lightning strikes and corona at exposed fuel vent outlets. Protection against indirect ignition sources such as fuel tank wiring is also applicable.
*
29.1309 - Equipment, Systems, and Installations. This regulation requires that flight-critical and essential systems, equipment, and functions be designed and installed to continue to perform their intended functions under any foreseeable operating condition, and requires, specifically, that the direct and indirect effects of lightning be considered in complying with this regulation.
29.610 - Lightning protection. This is the basic airframe lightning protection regulation, which requires that the rotorcraft be able to sustain a lightning strike without catastrophic damage.
*
29.954 - Fuel System Lightning Protection. This regulation requires that fuel tanks and systems be free of ignition sources such as electrical arcs and sparks due to direct or swept lightning strikes and corona at exposed fuel vent outlets. Protection against indirect ignition sources such as fuel tank wiring is also applicable.
*
29.1309 - Equipment, Systems, and Installations. This regulation requires that flight-critical and essential systems, equipment, and functions be designed and installed to continue to perform their intended functions under any foreseeable operating condition, and requires, specifically, that the direct and indirect effects of lightning be considered in complying with this regulation.
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'95 Bristow SuperPuma lightning strike
Have got my hands on the documentary recently showed on the National Geographic Channel, about the SuperPuma from Bristow that ditched into the North Sea after a lightning strike in 1995, I think it was ..
You can download it from here - Danish subtitles and lower quality due to long documentary, but usable and informative:
Section 1 (25Mb): http://www.madman.dk/movies/bristow_...per_puma_1.wmv
Section 2 (41Mb): http://www.madman.dk/movies/bristow_...per_puma_2.wmv
Section 3 (31Mb): http://www.madman.dk/movies/bristow_...per_puma_3.wmv
Section 4 (22Mb): http://www.madman.dk/movies/bristow_...per_puma_4.wmv
- madman
You can download it from here - Danish subtitles and lower quality due to long documentary, but usable and informative:
Section 1 (25Mb): http://www.madman.dk/movies/bristow_...per_puma_1.wmv
Section 2 (41Mb): http://www.madman.dk/movies/bristow_...per_puma_2.wmv
Section 3 (31Mb): http://www.madman.dk/movies/bristow_...per_puma_3.wmv
Section 4 (22Mb): http://www.madman.dk/movies/bristow_...per_puma_4.wmv
- madman
Nick, as you know you can only "grandfather" when you don't change the design. The EC225 has all-new blades so for your information they are of course compliant with the latest version of JAR and FAR29 for lightning strike tolerance.
Nick-bashing aside, I would also point out that whilst the manufacturers are well aware of the maximum action integral of lightning that their blades must tolerate, Mother Nature is not so well aware and may decide to discharge more than the maximum into your blades - so best to avoid getting struck!
On the metal versus composite blades argument, neither likes lightning very much. The metal blades tend to have pockets blown partially off which really upsets the aerodynamics causing very severe vibration. And as we know there is the possibility of damage to the spar. The composite blades tend to vapourise on the inside blowing off big chunks and leaving steams of fibre trailing. But overall I would prefer fullly composite blades because they don't have spars - therefore they tend to be more damage tolerant (distributed loads and all that). I have seen some scary-looking blades that flew for 100miles or so with the pilots blissfully unaware.
Apart from the blade damage the whole drivetrain may need replacing due to magnetisation and arc damage - a very expensive excercise!
In the North Sea we (as a group) get struck by lighting typically once per year, nearly always in winter and nearly always with the OAT around zero. We don't normally get struck by the sort of lightning that comes out a big red (on the radar) Cb, instead it seems that the aircraft triggers the lighting by its passage. Probably the trail of ionised air that is generated by static discharge and engine exhaust gas - a bit like trailing a long wire behind the aircraft.
And its no co-incidence that it occurs typically around zero C - at this temperature there is mixed-phase water (ie liquid and solid water). The solid is lighter and tends to be pulled up in the updraft, whilst the liquid is heavier and tends to sink. This pulling apart leads to charge separation with the maximum electric field strength near the zero degree level.
And that explains why we only get struck in winter - because only in winter are we flying around near the zero degree level.
Or something like that.....
HC
Nick-bashing aside, I would also point out that whilst the manufacturers are well aware of the maximum action integral of lightning that their blades must tolerate, Mother Nature is not so well aware and may decide to discharge more than the maximum into your blades - so best to avoid getting struck!
On the metal versus composite blades argument, neither likes lightning very much. The metal blades tend to have pockets blown partially off which really upsets the aerodynamics causing very severe vibration. And as we know there is the possibility of damage to the spar. The composite blades tend to vapourise on the inside blowing off big chunks and leaving steams of fibre trailing. But overall I would prefer fullly composite blades because they don't have spars - therefore they tend to be more damage tolerant (distributed loads and all that). I have seen some scary-looking blades that flew for 100miles or so with the pilots blissfully unaware.
Apart from the blade damage the whole drivetrain may need replacing due to magnetisation and arc damage - a very expensive excercise!
In the North Sea we (as a group) get struck by lighting typically once per year, nearly always in winter and nearly always with the OAT around zero. We don't normally get struck by the sort of lightning that comes out a big red (on the radar) Cb, instead it seems that the aircraft triggers the lighting by its passage. Probably the trail of ionised air that is generated by static discharge and engine exhaust gas - a bit like trailing a long wire behind the aircraft.
And its no co-incidence that it occurs typically around zero C - at this temperature there is mixed-phase water (ie liquid and solid water). The solid is lighter and tends to be pulled up in the updraft, whilst the liquid is heavier and tends to sink. This pulling apart leads to charge separation with the maximum electric field strength near the zero degree level.
And that explains why we only get struck in winter - because only in winter are we flying around near the zero degree level.
Or something like that.....
HC
Thanks for the link Madman.
UnDies,on the instruments side you should check (by the 139 FM):
— barometric setting and displayed altitude
— selected altitude
— selected navigational aid
— selected course
— selected heading
— selected decision height
— selected radio frequencies (including radio comms transmission check)
Regards
UnDies,on the instruments side you should check (by the 139 FM):
— barometric setting and displayed altitude
— selected altitude
— selected navigational aid
— selected course
— selected heading
— selected decision height
— selected radio frequencies (including radio comms transmission check)
Regards
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Recently one of their L2's was struck twice in a month. The second strike was very large and the aircraft returned to base with no major problems in flight.
Upon inspection, extensive damage to components, some of which had never been seen by the AAIB.
Upon inspection, extensive damage to components, some of which had never been seen by the AAIB.
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Redhot are you reffering to the incident in Penticton British Columbia Canada?
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Lightning strikes to helis
I'm trying to get a handle on lightning strikes to helis. Apart from lightning strikes to helis operating on the North Sea and the strike to a Vietnamese Puma (subject of a recent Eurocopter Service Letter) can anyone advise me of strikes to turbine powered helis elsewhere in the world. If possible I would welcome details of type of heli, when and where event happened and, briefly, what the result was. Lightning strikes, as such, where the heli continues flight and lands safely, are normally not classed as accidents or serious incidents so don't turn up in the 'accident record'.
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Hi:
Heli Jet airways had a lioghtning strike, I'm guessing 7 or 8 years ago.
They operate a schedule service between Vancouver and Victoria, British Columbia using Sikorsky S-76 A aircraft.
I don't remember all the details, but they were hit in cruise(I think) . The aircraft was grounded for about a year after. The gear boxes all had to be rebuilt becuse of arcing on the gear teeth.
Sorry I can't help you with more details. Maybe if you sent them an e-mail they could probably fill you in.
http://http://www.helijet.com/about/about.php?pageID=51
Heli Jet airways had a lioghtning strike, I'm guessing 7 or 8 years ago.
They operate a schedule service between Vancouver and Victoria, British Columbia using Sikorsky S-76 A aircraft.
I don't remember all the details, but they were hit in cruise(I think) . The aircraft was grounded for about a year after. The gear boxes all had to be rebuilt becuse of arcing on the gear teeth.
Sorry I can't help you with more details. Maybe if you sent them an e-mail they could probably fill you in.
http://http://www.helijet.com/about/about.php?pageID=51
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MR Nosey, you have got it wrong, HJ had to remove a blade that was purchased somewhere else that had a lightning strike recorded on the logcard, I know because I removed it. Sikorsky asked all operators that any MR blade with history of lightning strike be removed from service, it was after a North Sea incident where a blade failed after a lightning strike.
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It is important to know that FAR/JAR have been very much updated in the last several years to harden helos to lightning strikes. The 139 and 92 have been designed and tested to these new requirements, which are so pervasive that they are not within the realm of retrofit.
H-53 Lightning Strike
We had an brand spanking new MH-53E at Sikorsky sustain an in-flight lightning strike approximately 15 years ago. The lightning struck a main rotor blade, as evidenced by a burn spot (5 inches in diameter) on the skin. A second indication was noted at the current exit point on a tail rotor blade. The tail rotor blade’s composite material was blown apart at the trailing edge leaving a fan of composite hair like material blowing in the wind. Post strike, the helicopter received a thorough engineering inspection and investigation. This investigation revealed that most ferrous parts along the current path were magnetized and required degaussing. Burn spots were also noted along gaps between the cargo door, ramp and the airframe.
For the remainder of its service life this aircraft was known as Lightning Bolt and all subsequent aircraft problems were blamed on this early life event.
For the remainder of its service life this aircraft was known as Lightning Bolt and all subsequent aircraft problems were blamed on this early life event.
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http://www.ntsb.gov/ntsb/query.asp#query_start
give several hits if you query helicopter and text query lightning.
give several hits if you query helicopter and text query lightning.
Lightning Strikes
In sub-tropical areas of the world, there are many occasions where lightning conditions exist hand in hand with a flying task and yet, as far as I am aware, there have been no lightning strikes to helicopters flying in these conditions – and they do, either inadvertently or in a no choice situation. However, on the North Sea for example, as most are aware, lightning strikes are a significant hazard, even in clear air. It may be there is a relationship between humidity/temperature and other meteorological factors that can significantly reduce the possibility of a strike. If this assumption, and that’s all it is, is generally correct, is anyone aware of any research that has taken place regarding this aspect?
Apologies in advance for the laymans language.....
There has been alot of research done, and I think the conclusion is that the strikes tend to happen around the 0°C air band (+/- a bit!) So, this puts helicopters smack in the middle of this region in the North Sea for much of the year. Basically, the charge is developed from friction between slightly wet water crystals rubbing together as they change levels in the cloud and you end up with one set of charged crystals in the region just mentioned, and the opposite charged crystal higher. Normally this continues until the electrical potential is large enough to bridge the gap, unless some other helpful initiator passes by - like an aircraft! Aircraft are themselves highly charged, and are also leaving an ion trail from their exhausts - they may as well tow a line of copper wire!
So, in the North sea the helicopter actually causes the lightning and then attracts it, whereas in the tropics the lightning has occurred 'naturally' at a high level and it is more or less bad luck to be in the way as it passes to earth. Or, the aircraft is on the ground and acts as a handy lightning conductor!
Of course, it's not only helicopters that get struck - turboprops are very succeptible in warm climates as they stagger slowly through the 0°C levels, and FW in general do suffer strikes on their way up and down. The big difference is that helicopters are more vulnerable to the potential damage that results.
Having spent the last 15 years flying in equatorial lattitudes, I can vouch that the lightning is pretty incredible, and I'm very glad that this characteristics is true
There has been alot of research done, and I think the conclusion is that the strikes tend to happen around the 0°C air band (+/- a bit!) So, this puts helicopters smack in the middle of this region in the North Sea for much of the year. Basically, the charge is developed from friction between slightly wet water crystals rubbing together as they change levels in the cloud and you end up with one set of charged crystals in the region just mentioned, and the opposite charged crystal higher. Normally this continues until the electrical potential is large enough to bridge the gap, unless some other helpful initiator passes by - like an aircraft! Aircraft are themselves highly charged, and are also leaving an ion trail from their exhausts - they may as well tow a line of copper wire!
So, in the North sea the helicopter actually causes the lightning and then attracts it, whereas in the tropics the lightning has occurred 'naturally' at a high level and it is more or less bad luck to be in the way as it passes to earth. Or, the aircraft is on the ground and acts as a handy lightning conductor!
Of course, it's not only helicopters that get struck - turboprops are very succeptible in warm climates as they stagger slowly through the 0°C levels, and FW in general do suffer strikes on their way up and down. The big difference is that helicopters are more vulnerable to the potential damage that results.
Having spent the last 15 years flying in equatorial lattitudes, I can vouch that the lightning is pretty incredible, and I'm very glad that this characteristics is true
Last edited by 212man; 10th May 2010 at 12:14. Reason: edited to change 'fiction' to 'friction' though possibly the former is correct!
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Lightning Strikes in Flight?
So, I'm flying in Florida (The lightning capital of the world) and wondering if anyone has information on strikes to helicopters in flight? I've heard details on a Bristow Super Puma ditching in the N. Sea several years ago after a nasty tail rotor gearbox strike but wondered how often it happens?
Anyone with any experiences of links to tech docs?
Thanks
Anyone with any experiences of links to tech docs?
Thanks