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1. 08:08 AM - Re: Static Events On Composite Airplanes (William Hunter)
2. 10:18 AM - Re: Static Events On Composite Airplanes (Robert L. Nuckolls, III)
Message 1
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| Subject: | Re: Static Events On Composite Airplanes |
Thanks Sebastien for the information. Greatly appreciated.
Does anyone else have any information that they can share?
On 3/3/2022 4:24 PM, Sebastien wrote:
> Hello Bill,
>
> I don't have any data, just anecdotalevidence that flying IMC witha
> composite amateur built aircraft is risky. You could look up the
> bonding section in the certification requirements for composite
> aircraft,that would probably give you a good idea of how thorough you
> have to be tomake a composite aircraft safe for IMC flights.
> I have flown several different models of certified fiberglass aircraft
> IFR. These aircraft are designed and built with conductive mesh
> throughout the airframe to dissipate any static electricity build up.
> Despite this, on two different occasions I have had severe problems
> with static while IMC requiringa diversion. In one case it was so bad
> that the student was getting electric shocks through the yoke. The
> other incident took out half the avionics and magnetized the compass.
>
> As for lightning, I think usually the aircraft gets destroyed by
> turbulence induced loss of control before getting close enough to be
> hit by lightning but I know of one incident with a glider in the UK
> which was flying near what they thought was stratus cloud but had an
> embedded CB in it. The composite glider (factory built but with no
> bonding material embedded) basically exploded when it was hit. Very
> high resistance = very high temperature during a lightning strike and
> the entire airframe disintegrated. They found themselves falling in
> free air but both successfully deployed their parachutes and survived.
> The passenger was on his first small aircraft flight.
>
> I think anyone flying IMC regularly in a composite amateur built
> aircraft is going to run into a problem sooner or later. I know of no
> solution, everyone just seems to roll the dice and hope they keep
> getting 7s.
>
> On Thu, Mar 3, 2022 at 8:28 AM William Hunter
> <billhuntersemail@gmail.com> wrote:
>
> Greetings,
>
> I fly a composite airplane that is built using a foam core with
> regular fiberglass BID material bonded to the core for most of the
> construction and flight control surfaces and then in some small
> sections there is some carbon fiber bonded in to certain places of
> the structure where needed for extra support so essentially the
> airplane is mostly core foam and regular fiberglass.
>
> There has been one static event in the community where the pilot
> of this type of airplane who had a full EFIS system was climbing
> through dry snow and his Garmin EFIS screen blacked out and then a
> few minutes later the screen returned however the autopilot was
> still operating as usual so it seems that it was only the EFIS
> screen that was affected during the event and not the rest of the
> system. The data was downloaded and sent to Garmin and they
> determined that it was a static discharge. I have not heard what
> their remedy was for this concern.
>
> So the questions that popped up are the following...
>
> -How does the builder/ pilot mitigate the risk of this type of
> issue from happening in a composite airplane?
>
> -Is this a common concern in airplanes designed like this?
>
> -There are commercially available static wicks that could be
> attached to the structure however if the structure does not have
> any kind of conductive material/ mesh embedded in the fiberglass I
> would not think that the static buildup would get to the static wicks.
>
> -The plans do not call for any type if bonding cable be installed
> to electrically connect the flight controls to the fuselage so the
> question is...should there be bonding straps in this type of airplane?
>
> -What risks does an airplane like this have when flying near
> lightning?
>
> -If the fuselage was not conductive and there is no practical way
> to get it to discharge the static through static wicks then what
> other technique is there to mitigate the risk of static buildup
> damaging/ disabling the electrical components of the airplane?
>
> -And other questions that we are not smart enough to know to ask?
>
> THANKS all and as always I am very grateful for your advice and
> expertise.
>
> Bill
>
>
Message 2
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| Subject: | Re: Static Events On Composite Airplanes |
At 10:23 AM 3/3/2022, you wrote:
>Greetings,
>
>I fly a composite airplane that is built using a
>foam core with regular fiberglass BID material
>bonded to the core for most of the construction
>and flight control surfaces and then in some
>small sections there is some carbon fiber bonded
>in to certain places of the structure where
>needed for extra support so essentially the
>airplane is mostly core foam and regular fiberglass.
>
>There has been one static event in the community
>where the pilot of this type of airplane who had
>a full EFIS system was climbing through dry snow
>and his Garmin EFIS screen blacked out and then
>a few minutes later the screen returned however
>the autopilot was still operating as usual so it
>seems that it was only the EFIS screen that was
>affected during the event and not the rest of
>the system.=C2 The data was downloaded and sent
>to Garmin and they determined that it was a
>static discharge.=C2 I have not heard what their remedy was for this
concern.
>
>So the questions that popped up are the following...
>
>-How does the builder/ pilot mitigate the risk
>of this type of issue from happening in a composite airplane?
Control of p-static in aircraft is a blend of
science and practice derived from over a century
of observation and attempts at mitigation. Bottom
line is that you can attenuate the effects of
p-static on most aircraft but it's ranges
exceedingly difficult up to impossible to
reduce effects to negligible.
There are file cabinets full of test reports
and studies on p-static management in
type certificated aircraft . . . all metal
ones at that. There are companies that
specialize in identification of optimal
placement of static wicks.
They set the airplane up on insulators and
charge the airframe with tens of thousands
of volts. Then they walk around the airplane
with a hand held probe (a very long one!)
and search out locations on the airframe
most conducive to forming a corona discharge.
Those locations are deemed best locations
for static wicks.
I asked a p-static guy at Piper that given
the high-velocity nature of p-static generation,
how do they know that those explorations at zero
airspeed correspond to the same locations
that exist in flight? "We don't", sez he,
"just a best guess". A guess that costs a
few $thousand$ to make.
Now, ask one of those guys to survey your plastic
airplane and all bets are off. Static-charge
mitigation is absolutely dependent on conductivity
between the generation surface and the ideal
discharge locations.
>-Is this a common concern in airplanes designed like this?
Yup
>-There are commercially available static wicks that could be attached
>to the structure however if the structure does not have any kind
>of conductive material/ mesh embedded in the fiberglass I would
>not think that the static buildup would get to the static wicks.
Exactly right.
>-The plans do not call for any type if bonding cable be installed
>to electrically connect the flight controls to the fuselage so
>the question is...should there be bonding straps in this type of airplane?
There is no foundation in physics that supports
an oft cited value in 'bonding' all the metal
stuff together in a plastic airplane.
>-What risks does an airplane like this have when flying near lightning?
See https://tinyurl.com/hre2hkz
I am aware of no incident where in-flight strike
brought down an OBAM airplane or caused injury to
crew. If anyone runs across such a case, I'd
like to hear about it. I recall a case where
an airplane was struck on the ramp and burned
(a GlasAir I think).
>-If the fuselage was not conductive and there is no practical way to
>get it to discharge the static through static wicks then what other
>technique is there to mitigate the risk of static buildup
>damaging/disabling the electrical components of the airplane?
There was a lot of head-scratching and long
discussions over beers at Lancair 20+ years ago
as they explored ways to make their products
more resistant to the effects of lightning
and p-static. The activity seemed to die off
with no significant advances/changes to the
airplane's design. I may be out of date on
that . . . again, if anyone has more current
info on p-static/lightning issues on OBAM
aircraft, please let me know.
The heavy iron birds EXPECT to receive in-flight
strikes . . . with some regularity. See
https://tinyurl.com/ydh37e4s
Type certification for (1) flight in to known
ice and (2) standing off lightning strike is
an arduous and expensive task and is still only
90% sure. There have been some unhappy outcomes
due to strike on large aircraft.
https://tinyurl.com/bdf47pzk
https://tinyurl.com/245d3wzz
My instructors always advised that a weather
briefing was the best prophylactic for such
risks . . . from wheels up to plop down,
flying should be fun.
Bob . . .
Un impeachable logic: George Carlin asked, "If black boxes
survive crashes, why don't they make the whole airplane
out of that stuff?"
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