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billhuntersemail(at)gmail
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 Posted: Thu Mar 03, 2022 8:24 am Post subject: Static Events On Composite Airplanes |
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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
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cluros(at)gmail.com
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| Posted: Thu Mar 03, 2022 3:24 pm Post subject: Static Events On Composite Airplanes |
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Hello Bill,
I don't have any data, just anecdotal evidence that flying IMC with a 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 to make 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 requiring a 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(at)gmail.com (billhuntersemail(at)gmail.com)> wrote:
| Quote: | 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
|
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billhuntersemail(at)gmail
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| Posted: Fri Mar 04, 2022 8:08 am Post subject: Static Events On Composite Airplanes |
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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:
| Quote: | Hello Bill,
I don't have any data, just anecdotal evidence that flying IMC with a 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 to make 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 requiring a 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(at)gmail.com (billhuntersemail(at)gmail.com)> wrote:
| Quote: | 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
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nuckolls.bob(at)aeroelect
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| Posted: Fri Mar 04, 2022 10:18 am Post subject: Static Events On Composite Airplanes |
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At 10:23 AM 3/3/2022, you wrote:
| Quote: | 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? |
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.
| Quote: | | -Is this a common concern in airplanes designed like this? |
Yup
| Quote: | -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.
| Quote: | -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.
| Quote: | | -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).
| Quote: | -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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Peter(at)sportingaero.com
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| Posted: Sat Mar 05, 2022 12:47 am Post subject: Static Events On Composite Airplanes |
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Dear Bill & Sebastien,
- flying IMC with a composite amateur built aircraft is risky
I really disagree with this statement. I also really disagree that the certification rules are particularly relevant as they are designed to mainly address lightning strike. It is worth looking at the data that is available.
Some years ago I undertook an investigation for the UK homebuilt association into IMC & night flying for homebuilts as UK homebuilts were limited to day VFR. The conclusion was the risk of lightning strike on single engined aircraft in IMC is so small it is not worth worrying about. The risk of lightning strike in VMC was already accepted (and is also very small). From the accident data for 40 years of flying in the UK and 10 years in the US there was only one instance of a single engined aircraft flying in IMC being hit by lightning, a 210 in the eastern US, and that ended with a diversion and safe landing. For whatever reason single engined aircraft are not hit by lightning. I do completely agree that the thunderstorm is much more likely to kill you than being hit by lightning! In the period we looked at around 60 aircraft, flying in IMC, came to grief because of flying into a thunderstorm.
I have no experience of the effects of static discharge. We found no similar instances to yours when we searched the accident/incident reports, but that was 10 years ago and the number of EFIS equipped aircraft has increased considerably in the intervening years. However, EFIS (or solid state instruments) are between 2 and 5 times more reliable than vacuum or electric gyros. It doesn’t matter if the instruments are certified or experimental, apart from the first 50 or so hours.
Flying in IMC in any single engined aircraft is inherently more risky than in VMC, but the level of increased risk is not easy to determine. The impact of electrical phenomenon on single engined aircraft in IMC are very difficult to measure from accident/incident data as there are very few reported incidents.
I work at a Part 145 repair company, we maintain and repair several types of composite light aircraft. In general the outer layer of carbon has aluminium woven into it to improve conductivity – carbon laminates are conductive. There is usually 20mm wide 1mm thick aluminium bonding straps throughout the aircraft. They all use static discharge wicks on the te of the wing tips and empennage. We have a fleet of around 20 aircraft on our books for maintenance, most involved in commercial training, and have not had a similar incident to yours reported. Including such “protection” in a homebuilt would not be something to be undertaken lightly, I am not convinced it would buy very much except a longer build time, lower useful load and corroded wings.
In the UK certified gliders (with little bonding or protection) regularly fly in IMC. I am not aware of any static problems. The incident of the K-21 being blown apart by lightning was when the glider knowingly flew (in VMC) close but not into a CB, it wasn’t a embedded in stratus. The strike was so severe that the moisture within the structure was heated so rapidly that it vapourised and blew the structure apart, the control rods were melted and fused together. Fortunately the pilots wore parachutes and escaped. The amount of energy absorbed by the aircraft meant that it was unlikely to have been survivable no matter how much bonding was used.
Most recreational pilots don’t fly in hard IMC for very long – even in the UK where we seem to have more low stratus than many other countries. The usual operational profile is to climb through the clag to VMC on top. Clearly commercial flight training spends much more time in the soup, but certainly here homebuilts cannot be used for commercial training. The conclusion we came to was that no additional requirements from the bonding perspective were required for homebuilt aircraft to fly in IMC, except to impose a limitation not to fly near areas of forecast or actual thunderstorms – although that is not policeable but it keeps the certification authorities happy!
Peter
From: owner-aeroelectric-list-server(at)matronics.com <owner-aeroelectric-list-server(at)matronics.com> On Behalf Of Sebastien
Sent: 03 March 2022 23:24
To: aeroelectric-l. <aeroelectric-list(at)matronics.com>
Subject: Re: Static Events On Composite Airplanes
Hello Bill,
I don't have any data, just anecdotal evidence that flying IMC with a 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 to make 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 requiring a 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(at)gmail.com (billhuntersemail(at)gmail.com)> wrote:
| Quote: |
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
|
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Peter(at)sportingaero.com
Guest
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| Posted: Sat Mar 05, 2022 1:16 am Post subject: Static Events On Composite Airplanes |
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Perhaps I should add that we looked at some kind of “IMC lite” clearance and quickly came to the conclusion that it was not possible. The aircraft is either clear for IMC or it is not. That doesn’t mean the pilot should press on regardless. Known icing capability in homebuilts is very unusual. With regard to the aircraft climbing through snow, I would question the pilot’s sanity! Flying in visible moisture in an aircraft with no icing protection does not seem sensible to me…
I guess the question is how much are you prepared to spend to be able to penetrate all conceivable weather conditions. Sounds like the pilot concerned found the edge of his system’s envelope and was lucky to be able to report his findings… Not my idea of fun!
Peter
From: owner-aeroelectric-list-server(at)matronics.com <owner-aeroelectric-list-server(at)matronics.com> On Behalf Of William Hunter
Sent: 04 March 2022 16:08
To: aeroelectric-list(at)matronics.com
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:
| Quote: |
Hello Bill,
I don't have any data, just anecdotal evidence that flying IMC with a 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 to make 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 requiring a 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(at)gmail.com (billhuntersemail(at)gmail.com)> wrote:
| Quote: |
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
|
|
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donjohnston
Joined: 13 Dec 2009
Posts: 231
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| Posted: Sat Mar 05, 2022 6:16 am Post subject: Re: Static Events On Composite Airplanes |
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My pilot side Grand Rapids HXr attitude and magnetic heading went wonky while flying through light rain in between layers. Showed a continuous steep descending left turn. That got my attention!
A/P automatically switched to the co-pilot side EFIS/AHRS. Once on the ground I rebooted it and performed fine.
GRT said it was probably a static discharge on the magnetometer that caused the problem. When I asked why a confused magnetometer would cause an indicated attitude change, I got some very weird reasoning. But I didn't design and build the box so okay. As to what I should do to prevent the issue, they suggested static wicks. Even though it's a composite airplane with no underlying conductive mesh? "Absolutely." My response was "What else ya got?"
They offered to sell me their Adaptive AHRS to replace my older Dual AHRS for almost nothing.
I think they discovered a flaw in their Dual AHRS and this was a way of fixing it without losing face.
I never did get around to installing the Adaptive AHRS and never had another event.
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Last edited by donjohnston on Sat Mar 05, 2022 8:48 am; edited 1 time in total |
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Ceengland
Joined: 11 Oct 2020
Posts: 379
Location: MS
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| Posted: Sat Mar 05, 2022 7:55 am Post subject: Static Events On Composite Airplanes |
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On 3/5/2022 8:16 AM, donjohnston wrote:
| Quote: | | Quote: | --> AeroElectric-List message posted by: "donjohnston" <don(at)velocity-xl.com> (don(at)velocity-xl.com)
My pilot side Grand Rapids HXr attitude and magnetic heading went wonky while flying through light rain in between layers. Showed a continuous steep descending left turn. That got my attention!
A/P automatically switched to the co-pilot side EFIS/AHRS. Once on the ground I rebooted it and performed fine.
GRT said it was probably a static discharge on the magnetometer that caused the problem. When I asked why a confused magnetometer would cause an indicated attitude change, I got some very weird reasoning. But I didn't design and build the box so okay. As to what I should do to prevent the issue, they suggested static wicks. Even though it's a composite airplane with now underlying conductive mesh? "Absolutely." My response was "What else ya got?"
They offered to sell me their Adaptive AHRS to replace my older Dual AHRS for almost nothing.
I think they discovered a flaw in their Dual AHRS and this was a way of fixing it without losing face.
I never did get around to installing the Adaptive AHRS and never had another event.
|
Even though it's a composite airplane with now underlying conductive mesh? "Absolutely." My response was "What else ya got?"
Well, aluminum airframes use static wicks; why not composite with conductive mesh? The wicks are there to bleed off the built-up charge.
Charlie
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billhuntersemail(at)gmail
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| Posted: Sat Mar 05, 2022 7:59 am Post subject: Static Events On Composite Airplanes |
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Good information...THANKS All for your relies!!!
On 3/4/2022 11:18 AM, Robert L. Nuckolls, III wrote:
| Quote: | At 10:23 AM 3/3/2022, you wrote:
| Quote: | 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? |
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.
| Quote: | | -Is this a common concern in airplanes designed like this? |
Yup
| Quote: | -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.
| Quote: | -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.
| Quote: | | -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).
| Quote: | -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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donjohnston
Joined: 13 Dec 2009
Posts: 231
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| Posted: Sat Mar 05, 2022 8:51 am Post subject: Re: Static Events On Composite Airplanes |
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| Ceengland wrote: | Even though it's a composite airplane with now underlying conductive mesh? "Absolutely." My response was "What else ya got?"
[/i]Well, aluminum airframes use static wicks; why not composite with conductive mesh? The wicks are there to bleed off the built-up charge.
Charlie
|
Should have been: no underlying conductive mesh.
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Ceengland
Joined: 11 Oct 2020
Posts: 379
Location: MS
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| Posted: Sat Mar 05, 2022 9:48 am Post subject: Static Events On Composite Airplanes |
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|
On Sat, Mar 5, 2022 at 10:55 AM donjohnston <don(at)velocity-xl.com (don(at)velocity-xl.com)> wrote:
| Quote: | --> AeroElectric-List message posted by: "donjohnston" <don(at)velocity-xl.com (don(at)velocity-xl.com)>
Ceengland wrote:
> Even though it's a composite airplane with now underlying conductive mesh? "Absolutely." My response was "What else ya got?"
>
> [/i]Well, aluminum airframes use static wicks; why not composite with conductive mesh? The wicks are there to bleed off the built-up charge.
>
> Charlie
>
Should have been: no underlying conductive mesh.
|
Still might well help, though you might need more of them. For instance, remember the old silk rag/glass rod science demo? Neither are conductive, but both can build up (opposite) charges. Anything you can do to bleed off the charge would be a good thing, don't you think?
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cluros(at)gmail.com
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| Posted: Sat Mar 05, 2022 5:32 pm Post subject: Static Events On Composite Airplanes |
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|
Hello Peter,
Like I said, I have no data. I included the anecdotes specifically because
I'm not sure that "We found no similar instances to yours when we searched
the accident/incident reports" is data either. An incident which takes out
half of the aircraft avionics and requires a diversion to a nearby VMC
airport would not show up in any accident database that I am aware of. No
one was injured and the aircraft did not suffer any damage after the
initial event. Both my incidents were in uncontrolled airspace so
definitely no report there. A friend of mine lost all avionics except for a
radio and the turn co-ordinator in an IMC static event over the rocky
mountains and required a great deal of help from controllers to safely get
the aircraft on the ground. Again, no database that I know of contains this
incident and it only happened 15 years ago.
Instrument failures happen for many reasons and when training IFR I go to
great lengths to make sure my students are as prepared as possible for them
but we rarely simulate losing most of the instrument panel. The closest we
get to that scenario is an alternator failure that eventually leaves us on
backup battery power for the approach.
These days I regularly see newly built amateur built that are IFR capable.
Many of these are built by pilots who have no IMC experience. Sometimes the
builder has given some thought to fault tolerance, other times not. I have
yet to see one where the builder gave any thought to static problems, so I
share my anecdotes and my caution to encourage builders to think about the
possibilities. All flying is risky to some degree so I suppose my statement
isn't very useful. I'm just trying to point out the increase in risk.
On Sat, Mar 5, 2022 at 1:01 AM Peter Pengilly <Peter(at)sportingaero.com>
wrote:
[quote] Dear Bill & Sebastien,
- flying IMC with a composite amateur built aircraft is risky
I really disagree with this statement. I also really disagree that the
certification rules are particularly relevant as they are designed to
mainly address lightning strike. It is worth looking at the data that is
available.
Some years ago I undertook an investigation for the UK homebuilt
association into IMC & night flying for homebuilts as UK homebuilts were
limited to day VFR. The conclusion was the risk of lightning strike on
single engined aircraft in IMC is so small it is not worth worrying about
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cluros(at)gmail.com
Guest
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| Posted: Sat Mar 05, 2022 5:38 pm Post subject: Static Events On Composite Airplanes |
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|
I have a student right now who is very much only interested in "IMC lite".
He just wants to get his instrument rating so that he can punch through a
layer on departure and be on his sunny way to a VMC destination. He's quite
bitter about having to learn how to operate down to 200' and 1/2 mile
visibility just to be able to do what he wants to do. But an instrument
rating is an instrument rating and it's the same rating to punch through a
cloud as it is to fly in a rainy cloud in the dark. Throw in some
instrument failures and it's not so much fun anymore. Best for pilots to
know the risks.
On Sat, Mar 5, 2022 at 1:19 AM Peter Pengilly <Peter(at)sportingaero.com>
wrote:
[quote] Perhaps I should add that we looked at some kind of “IMC lite” clearance
and quickly came to the conclusion that it was not possible. The aircraft
is either clear for IMC or it is not. That doesn’t mean the pilot should
press on regardless. Known icing capability in homebuilts is very unusual
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donjohnston
Joined: 13 Dec 2009
Posts: 231
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| Posted: Sun Mar 06, 2022 2:26 pm Post subject: Re: Static Events On Composite Airplanes |
|
|
| Ceengland wrote: | On Sat, Mar 5, 2022 at 10:55 AM donjohnston <don> wrote:
| Quote: | --> AeroElectric-List message posted by: "donjohnston" <don>
Ceengland wrote:
> Even though it's a composite airplane with now underlying conductive mesh? "Absolutely." My response was "What else ya got?"
>
> [/i]Well, aluminum airframes use static wicks; why not composite with conductive mesh? The wicks are there to bleed off the built-up charge.
>
> Charlie
>
Should have been: no underlying conductive mesh.
|
Still might well help, though you might need more of them. For instance, remember the old silk rag/glass rod science demo? Neither are conductive, but both can build up (opposite) charges. Anything you can do to bleed off the charge would be a good thing, don't you think? |
No, I don't.
It's one thing to build up a static charge on a non-conductive surface. Discharging it is an entirely different matter.
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Peter(at)sportingaero.com
Guest
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| Posted: Mon Mar 07, 2022 3:01 pm Post subject: Static Events On Composite Airplanes |
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|
Hello Sebastien,
All I can offer is that we searched the accident databases to find out what had been reported. If instances such as yours don’t get reported then nothing will get done until there is a nasty accident. Any decent safety management system seeks to collect “near-miss” data as a predictor of where accidents might happen, it is disappointing GA doesn’t do that.
Many homebuilders don’t understand how their aircraft could fail and put far too much trust in the promises of electronics salesmen. The UK CAA forced us to assess each individual aircraft applying for an IMC clearance to look at the power architecture of the instrument system. Several have had to make changes to increase the robustness/resilience or to look at what loads must be shed if the alternator fails. We have no requirements for static build-up protection.
Peter
From: owner-aeroelectric-list-server(at)matronics.com <owner-aeroelectric-list-server(at)matronics.com> On Behalf Of Sebastien
Sent: 06 March 2022 01:31
To: aeroelectric-l. <aeroelectric-list(at)matronics.com>
Subject: Re: Static Events On Composite Airplanes
Hello Peter,
Like I said, I have no data. I included the anecdotes specifically because I'm not sure that "We found no similar instances to yours when we searched the accident/incident reports" is data either. An incident which takes out half of the aircraft avionics and requires a diversion to a nearby VMC airport would not show up in any accident database that I am aware of. No one was injured and the aircraft did not suffer any damage after the initial event. Both my incidents were in uncontrolled airspace so definitely no report there. A friend of mine lost all avionics except for a radio and the turn co-ordinator in an IMC static event over the rocky mountains and required a great deal of help from controllers to safely get the aircraft on the ground. Again, no database that I know of contains this incident and it only happened 15 years ago.
Instrument failures happen for many reasons and when training IFR I go to great lengths to make sure my students are as prepared as possible for them but we rarely simulate losing most of the instrument panel. The closest we get to that scenario is an alternator failure that eventually leaves us on backup battery power for the approach.
These days I regularly see newly built amateur built that are IFR capable. Many of these are built by pilots who have no IMC experience. Sometimes the builder has given some thought to fault tolerance, other times not. I have yet to see one where the builder gave any thought to static problems, so I share my anecdotes and my caution to encourage builders to think about the possibilities. All flying is risky to some degree so I suppose my statement isn't very useful. I'm just trying to point out the increase in risk.
On Sat, Mar 5, 2022 at 1:01 AM Peter Pengilly <Peter(at)sportingaero.com (Peter(at)sportingaero.com)> wrote:
| Quote: |
Dear Bill & Sebastien,
- flying IMC with a composite amateur built aircraft is risky
I really disagree with this statement. I also really disagree that the certification rules are particularly relevant as they are designed to mainly address lightning strike. It is worth looking at the data that is available.
Some years ago I undertook an investigation for the UK homebuilt association into IMC & night flying for homebuilts as UK homebuilts were limited to day VFR. The conclusion was the risk of lightning strike on single engined aircraft in IMC is so small it is not worth worrying about. The risk of lightning strike in VMC was already accepted (and is also very small). From the accident data for 40 years of flying in the UK and 10 years in the US there was only one instance of a single engined aircraft flying in IMC being hit by lightning, a 210 in the eastern US, and that ended with a diversion and safe landing. For whatever reason single engined aircraft are not hit by lightning. I do completely agree that the thunderstorm is much more likely to kill you than being hit by lightning! In the period we looked at around 60 aircraft, flying in IMC, came to grief because of flying into a thunderstorm.
I have no experience of the effects of static discharge. We found no similar instances to yours when we searched the accident/incident reports, but that was 10 years ago and the number of EFIS equipped aircraft has increased considerably in the intervening years. However, EFIS (or solid state instruments) are between 2 and 5 times more reliable than vacuum or electric gyros. It doesn’t matter if the instruments are certified or experimental, apart from the first 50 or so hours.
Flying in IMC in any single engined aircraft is inherently more risky than in VMC, but the level of increased risk is not easy to determine. The impact of electrical phenomenon on single engined aircraft in IMC are very difficult to measure from accident/incident data as there are very few reported incidents.
I work at a Part 145 repair company, we maintain and repair several types of composite light aircraft. In general the outer layer of carbon has aluminium woven into it to improve conductivity – carbon laminates are conductive. There is usually 20mm wide 1mm thick aluminium bonding straps throughout the aircraft. They all use static discharge wicks on the te of the wing tips and empennage. We have a fleet of around 20 aircraft on our books for maintenance, most involved in commercial training, and have not had a similar incident to yours reported. Including such “protection” in a homebuilt would not be something to be undertaken lightly, I am not convinced it would buy very much except a longer build time, lower useful load and corroded wings.
In the UK certified gliders (with little bonding or protection) regularly fly in IMC. I am not aware of any static problems. The incident of the K-21 being blown apart by lightning was when the glider knowingly flew (in VMC) close but not into a CB, it wasn’t a embedded in stratus. The strike was so severe that the moisture within the structure was heated so rapidly that it vapourised and blew the structure apart, the control rods were melted and fused together. Fortunately the pilots wore parachutes and escaped. The amount of energy absorbed by the aircraft meant that it was unlikely to have been survivable no matter how much bonding was used.
Most recreational pilots don’t fly in hard IMC for very long – even in the UK where we seem to have more low stratus than many other countries. The usual operational profile is to climb through the clag to VMC on top. Clearly commercial flight training spends much more time in the soup, but certainly here homebuilts cannot be used for commercial training. The conclusion we came to was that no additional requirements from the bonding perspective were required for homebuilt aircraft to fly in IMC, except to impose a limitation not to fly near areas of forecast or actual thunderstorms – although that is not policeable but it keeps the certification authorities happy!
Peter
From: owner-aeroelectric-list-server(at)matronics.com (owner-aeroelectric-list-server(at)matronics.com) <owner-aeroelectric-list-server(at)matronics.com (owner-aeroelectric-list-server(at)matronics.com)> On Behalf Of Sebastien
Sent: 03 March 2022 23:24
To: aeroelectric-l. <aeroelectric-list(at)matronics.com (aeroelectric-list(at)matronics.com)>
Subject: Re: Static Events On Composite Airplanes
Hello Bill,
I don't have any data, just anecdotal evidence that flying IMC with a 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 to make 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 requiring a 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(at)gmail.com (billhuntersemail(at)gmail.com)> wrote:
| Quote: |
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
|
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cluros(at)gmail.com
Guest
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| Posted: Mon Mar 07, 2022 4:33 pm Post subject: Static Events On Composite Airplanes |
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In Canada we have a similar process. Each aircraft is approved for IFR on a
case by case basis. A couple times I have had to go to great lengths to
educate the Airworthiness Inspector on their own regulations in order to
get an aircraft passed. There is no load analysis or power architecture
analysis though. Maybe a good thing considering the inspectors in question
but it's certainly an area rife for improvement.
One builder had spent a massive amount of time creating layers of backup
systems for his electrically dependent engine and his IFR avionics. After a
couple hundred hours on the aircraft he finally got his VFR restriction
removed and hired me to get his instrument rating. Early on in perfect VMC
at 6500' flying over an airport with 3 runways I asked him to turn the
master off to test his backups, he refused ... he'd never tested it in the
air or on the ground lol. We corrected both before taking the aircraft IMC.
A beautiful aircraft.
On Mon, Mar 7, 2022 at 3:07 PM Peter Pengilly <Peter(at)sportingaero.com>
wrote:
[quote] Hello Sebastien,
All I can offer is that we searched the accident databases to find out
what had been reported. If instances such as yours don’t get reported then
nothing will get done until there is a nasty accident. Any decent safety
management system seeks to collect “near-miss” data as a predictor of where
accidents might happen, it is disappointing GA doesn’t do that.
Many homebuilders don’t understand how their aircraft could fail and put
far too much trust in the promises of electronics salesmen. The UK CAA
forced us to assess each individual aircraft applying for an IMC clearance
to look at the power architecture of the instrument system. Several have
had to make changes to increase the robustness/resilience or to look at
what loads must be shed if the alternator fails. We have no requirements
for static build-up protection.
Peter
*From:* owner-aeroelectric-list-server(at)matronics.com <
owner-aeroelectric-list-server(at)matronics.com> *On Behalf Of *Sebastien
*Sent:* 06 March 2022 01:31
*To:* aeroelectric-l. <aeroelectric-list(at)matronics.com>
*Subject:* Re: Static Events On Composite Airplanes
Hello Peter,
Like I said, I have no data. I included the anecdotes specifically because
I'm not sure that "We found no similar instances to yours when we searched
the accident/incident reports" is data either. An incident which takes out
half of the aircraft avionics and requires a diversion to a nearby VMC
airport would not show up in any accident database that I am aware of. No
one was injured and the aircraft did not suffer any damage after the
initial event. Both my incidents were in uncontrolled airspace so
definitely no report there. A friend of mine lost all avionics except for a
radio and the turn co-ordinator in an IMC static event over the rocky
mountains and required a great deal of help from controllers to safely get
the aircraft on the ground. Again, no database that I know of contains this
incident and it only happened 15 years ago.
Instrument failures happen for many reasons and when training IFR I go to
great lengths to make sure my students are as prepared as possible for them
but we rarely simulate losing most of the instrument panel. The closest we
get to that scenario is an alternator failure that eventually leaves us on
backup battery power for the approach.
These days I regularly see newly built amateur built that are IFR capable
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