North Sea helicopters cause lightning to strike.

[G-CPTN]

BBC News - How North Sea helicopters cause lightning to strike (http://www.bbc.co.uk/news/uk-scotland-north-east-orkney-shetland-31206363)

[HeliComparator]

We have known this for at least 15 years. Although knowing it doesn't necessarily help.

The met office system works - on the basis that if you don't go flying you won't get struck! It would be interesting to know how much lost flying time was caused by the system, vs how many aircraft would normally have been struck. I suspect the false alarm rate is very high, ie lots of days of non- or restricted flying and hassle to save maybe 1 strike per year. Unless they can make it more reliable I'm not sure it's worth it.

[mtoroshanga]

As usual so called experts are doing there thing
From personal experiance I can say that lighting damage on Super pumas was because of faulty construction by manufacture resulting in an insulating resin between the conducting terminal on the tail rotor blade W hen this problem was resolved there was no problem. The other result of a lightning strike is damage to main rotor head bearings which could be detected by IHUMS or mag plug debris

[helimutt]

try flying in the tropics or far east. lightning is a regular occurence but how many helicopters have been struck out there? Freezing level isnt something a helicopter could achieve out there :E

[HeliComparator]

As usual so called experts are doing there thing
From personal experiance I can say that lighting damage on Super pumas was because of faulty construction by manufacture resulting in an insulating resin between the conducting terminal on the tail rotor blade W hen this problem was resolved there was no problem. The other result of a lightning strike is damage to main rotor head bearings which could be detected by IHUMS or mag plug debris


Not really. Even with everything correctly bonded there is a lot of damage arising from the current flow - arcing over gears and bearings in the head, gearbox etc, plus possible avionics damage. I think there have been instances of poor bonding on the rotors but this has not caused catastrophic damage, but perhaps increased blade damage (whilst still allowing continued flight). The original Super Puma's tail rotors were certified to a lesser maximum current integral which, in the case of G-TIGK was exceeded by nature, resulting in unexpectedly wet feet.


Every lightning strike IS a problem, not because it terminates the flight but because of the cost of replacing all the damaged and magnetised bits. I think it averaged £0.5 million per strike when we looked at it many years ago. However, one could say it is just part of the operating costs and continue to "get on with it" rather than stopping flying on many days, so that the one strike that year is avoided.

[ericferret]

I saw a nice photograph circa 1996 of Helikopter Services chief engineer at Bergen with his head through a hole in a Super Puma main rotor blade post lightning strike.

Was not the loss of Bristow S76 G-BVJX that crashed out of Norwich about 2002 put down to undetected damage to a main rotor blade caused by a lightning strike?

http://www.aaib.gov.uk/publications/formal_reports/1_2005_g_bjvx.cfm

[AnFI]

eric - that 76 had a manufacturing defect which compounded by the lightening caused the fatality. but still not immediate failure, many flights later.

Anyone know of any immediate loss due lightening?

[HeliComparator]

Just G-TIGK I mentioned earlier. Tail rotor blown off but it made a sucessful ditching with no casualties.

[AnFI]

so not too dangerous then

[ericferret]

The blade manufacturing defect was estimated to produce a fatigue failure in the spar after 100,000 hours. This was based on the blade tang touching the spar for which there was no evidence in this case. As the blade was lifed at 37,000 it would never have been a factor without the strike. So I would say that the loss of the blade was due to a lightning strike compounded by a manufacturing defect. Which ever way you cut it the end result was the same.

What this and other incidents seem to point to is that aircraft design is basically sound but manufacturing and maintenance do not always achieve what the designer intended.

On the subject of false alarms the system went down last week giving a false indication and a number of aircraft were idle for no reason.

[ironchefflay]

The last Strike i saw, prob cost a lot more than £0.5m in manpower alone. (S92)

Then add 3 main blades 4 tail, new Complete MRH,MGB, IGB, TGB, Drive shafts, rework to the main lifting frames due to arching through the MGB bolt holes. Amongst a lot of other stuff. Prob 6 months or more in lost revenue.

Insurance bill for??????? multiple millions. and since theres always the possibility that if you get struck it could be that bad every time, im not surprised the flying gets cancelled.

[vfr440]

Confirm. In a VERY small way I was involved with the recovery of a B407 which was struck. Cost (insurers) a fortune :(. The arcing through the dynamic components almost the cost of new replacements; they didn't ring the Lutine Bell, but it was close :( - VFR

[HeliComparator]

so not too dangerous then

No, potentially very dangerous (only saved by a very competent crew) but after that accident (18 years ago) the tail rotor lightning strike tolerance was increased by at least 3-fold and Super Pumas were retrofitted with beefed up tail rotor blades, newer types certified to the higher current integral standard.