posted on Jan, 25 2015 @ 06:55 AM
a reply to: Arbitrageur
It probably pays to read the stated source you quoted yourself first carefully and then apply it in
context. Something you didn't do here.
The accident you quote took place almost exactly 20 years ago, long before composite airliners took to the air. A few years before that I knew someone
who was involved in the design work for what became the MD Explorer. This helicopter was fitted with a composite boom that has an embedded copper mesh
for lightening and static dissipation. And since at least then all composite components have had mitigation methods built into them. I have personally
inspected both composite and alloy components after lightening strikes so I have a good working knowledge of what to expect.
If you bothered to read the report you cite closely you will see that the particular rotor blades fitted by that operator did not have an embedded
mesh for a start, but a titanium strip. Also ironically they were chosen because of a much higher damage tolerance than the earlier CFRP type used on
earlier Puma family members. Further it was later found after this accident that the lightening strike data and survival standards used which stated
that a composite component must survive 98% of known strikes was woefully inadequate for the North Sea area which saw up to 30% of strikes exceeding
the damage tolerance limits. The strike that hit this particular aircraft is estimated to have exceeded the design limits by at least 300%, not a
fault of the materials or design per se but of the design standards used. In fact what failed was the inadequate titanium strip and the bonding lead.
And on top of that if you had read further you would have seen that the accident took place in mid January 1995 and before the end of that year the
manufacturer had designed a new blade that countered the deficiencies of the previous design and had made it available to operators, quite a decent
effort in aviation terms actually. I am not aware of any incidents like this regarding this model since then. The lightening strike protection
standards have also been increased since then and in fact as far back as 1982 there had been initial recommendations to do so, which was around the
time that this particular helicopter model was being designed and brought to market with this rotor blade design.
In short there are not composite helicopters or airliners being brought down by lightening on a regular basis because the designs account for this,
and just like those built of aluminium alloys have been adjusted as new data is found.
edit on 25-1-2015 by thebozeian because: (no reason given)