I’ve once seen a text (SA07-22) from Cirrus explaining that the 30 or so built „SRV“ models do not have this wire mesh in the composite and therefore are not able to ever fly IFR. This is also reflected in the EASA TCDS:
OTOH, I know SRV‘s in Europe that were equipped with IFR NAV units and converted/approved for IFR by the authority and are flying IFR.
For IFR certification a composite airframe needs a conductive (usually copper mesh) part in the layup, for lightning protection. Pipistrel are currently navigating this headache with trying to get the Panthers IFR certified.
Edit: I see Peter said the same in the OP :)
Probably – if all panels are interconnected, and the connection is continuous all the way to the static wicks.
I would expect an antenna to still need a metal ground plane.
Peter wrote:
Yes; carbon fibre is static “dissipative”
Is it sufficiently “dissipative” that you don’t need other anti-static measures for the comms?
Yes; carbon fibre is static “dissipative” but the conductivity is far too low to work for lightning.
The method which gives you both is a metal mesh in the composite. It’s not heavy but it is an extra step in the lay-up of the composite layers, and you have to make sure that contact can be made to it in the finished component. Just having a mesh in a fibreglass (or carbon) panel, which doesn’t connect to anything, is no good.
derek wrote:
I asked Elixir how they planned to get IFR certification given the carbon fibre construction and the risk of lightning strikes.
In my experience, carbon fiber is very conductive. Found this out the hard way, long story.
From here
Peter wrote:
and with a “plastic plane” one pretty well has to
I asked Elixir how they planned to get IFR certification given the carbon fibre construction and the risk of lightning strikes. They said there are two routes, embed something into the carbon fibre that provides lightning protection, or have onboard equipment, such as a stormscope, to allow one to stay away from lightning.
The said the first option was not practical for them, as it would add too much weight, so they were planning to go with the second option.
I presume, but don’t know for sure, that Cirrus and Diamond went for the first route.
Gliders have crashed after control linkages got melted by lighting.
But the radio is more likely affected. People flying “plastic” planes are fairly commonly chasing poor radio range issues. Especially homebuilts.
Ted.P wrote:
Without bonding a lightning strike could weld control surface hinges solid.
Never heard of that actually happening – but, if it did, it would surely ruin your whole day ..
