DHC Beaver down in Hawkesbury
Chemical spot detectors: Stay away from those ubiquitous el-cheapo adhesive-backed cardboard chemical spot detectors that are commonly sold by pilot shops and mail-order outfits for under trade names like “Dead Stop,” “Heads Up” and “Quantum Eye.” They have a very short useful life (about 30 days), and are extremely vulnerable to contamination from aromatic cleaners, solvents and other chemicals routinely used in aircraft maintenance.
These things often remain stuck on the instrument panel for years, providing a dangerous false sense of security. What’s worse, there’s no warning that the detector is outdated or has been contaminated—in some ways, that’s worse than not having a detector at all.
Even when fresh, chemical spot detectors are incapable of detecting low levels of CO. They’ll start turning color at 100ppm, but so slowly and subtly that you’ll never notice it. For all practical purposes, you’ll get no warning until concentrations rise to the 200 to 400 ppm range, by which time you’re likely to be too impaired to notice the color change.
These things often remain stuck on the instrument panel for years, providing a dangerous false sense of security. What’s worse, there’s no warning that the detector is outdated or has been contaminated—in some ways, that’s worse than not having a detector at all.
Even when fresh, chemical spot detectors are incapable of detecting low levels of CO. They’ll start turning color at 100ppm, but so slowly and subtly that you’ll never notice it. For all practical purposes, you’ll get no warning until concentrations rise to the 200 to 400 ppm range, by which time you’re likely to be too impaired to notice the color change.
Question without notice, Wingnuts: Did you have any direct or indirect involvement in the maintenance of the accident aircraft (registered as VH-NOO when the accident occurred) or then or now have any direct or indirect financial interest that would be affected by the cause/s of the accident? I declare that I don't.
For those that have been in a Beaver, what’s the airflow like in there, are they nice and air tight or does the wind blow in around the doors etc being such an old aircraft?
Comparing to say a Cirrus where their only airflow is via the vents on the dash.
Comparing to say a Cirrus where their only airflow is via the vents on the dash.
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Having over 6000 hrs in Beavers on Floats, a few years in hangers in the states maintaining them, an ex chief pilot in Sydney well before Sydney Seaplanes and then obviously been involved in the Cottage Point lunch flights many times, I am at loss to put any credence on the Carbon Monoxide theory. The construction of a Beaver has a very loose cowl fitting which gives an approximate fist size gap around approx 90% of the cowl and the airframe. All Beaver pilots I have flown with taxi with the pilot window down to keep fresh cool air circulating in the cabin. In most cases the pax window is down also. Being the time of day and the time of year I suspect both windows would have been wide open. With the take of direction the aircraft would have been taxied into wind with the occasional turn cross stream so as to avoid taxiing down wind. Down wind Taxi on water destroys propellers. There may have been a 360 turn or two involved so as not to extend the departure point too far east., but in any case there would be a very significant flow of fresh air in the cabin. A few holes in the firewall to allow CO into the cabin in sufficient volume to affect the pilot and passengers to me sounds extremely unlikely. BR
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Not ruling anything out, but I used to fly a machine that, when you hit the "smoker", it would fill the cockpit with smoke.
This was a pretty fair visible indication that whatever was leaving the RHS exhaust stack was heading in abundance into the cockpit.
That said, for anything to find its way in there must be something finding its way out.
This was a pretty fair visible indication that whatever was leaving the RHS exhaust stack was heading in abundance into the cockpit.
That said, for anything to find its way in there must be something finding its way out.
Not ruling anything out, but I used to fly a machine that, when you hit the "smoker", it would fill the cockpit with smoke.
This was a pretty fair visible indication that whatever was leaving the RHS exhaust stack was heading in abundance into the cockpit.
That said, for anything to find its way in there must be something finding its way out.
This was a pretty fair visible indication that whatever was leaving the RHS exhaust stack was heading in abundance into the cockpit.
That said, for anything to find its way in there must be something finding its way out.
As I noted earlier, airflow through cowlings can be counter-intuitive. The APS folk put cotton tufts and a camera under the hood of a Bonanza and discovered that, on a serviceable aircraft in the cruise, the air entered the outboard sides of the cowl openings and lots did a lap of the engine bay then exited forward through the inboard sides of those openings.
That data explained why an engine oil leak results in oil on the windscreen- at least on that aircraft and ones with similar cowl airflow ‘dynamics’.
Think about that: air flow both in and out of the same cowl opening. I say ‘opening’ rather than ‘inlet’, the latter of which is the label resulting from the intuitive belief that all air comes in the ‘front’ (the ‘inlets’) of the engine cowling and flows rear wards then exits somewhere different.
When there are cracks in exhaust plumbing and holes in the engine bay that shouldn’t be there, who knows where gasses may be flowing, absent some tuft/camera data to show what’s really happening?
And as I also noted earlier, if you think that the cabin windows/cockpit doors being wide open reduces the risk of potentially hazardous levels of CO in the cabin, my experience (with a reliable CO detector) is the opposite. But it did depend on a number of factors like wind direction/speed. The CO reading went to zero once all the windows/doors were closed and the aircraft was flying. The short term on-ground exposure to CO in a serviceable aircraft was evidently not deleterious. But who knows what could happen with repeated exposure during repeated short duration ops combined with with defects in the engine bay? The science shows that CO is very ‘sticky’ in the bloodstream.
Who knows what happened in this case. At least somebody’s entertaining the possibility that it’s not all the pilot’s fault.
That data explained why an engine oil leak results in oil on the windscreen- at least on that aircraft and ones with similar cowl airflow ‘dynamics’.
Think about that: air flow both in and out of the same cowl opening. I say ‘opening’ rather than ‘inlet’, the latter of which is the label resulting from the intuitive belief that all air comes in the ‘front’ (the ‘inlets’) of the engine cowling and flows rear wards then exits somewhere different.
When there are cracks in exhaust plumbing and holes in the engine bay that shouldn’t be there, who knows where gasses may be flowing, absent some tuft/camera data to show what’s really happening?
And as I also noted earlier, if you think that the cabin windows/cockpit doors being wide open reduces the risk of potentially hazardous levels of CO in the cabin, my experience (with a reliable CO detector) is the opposite. But it did depend on a number of factors like wind direction/speed. The CO reading went to zero once all the windows/doors were closed and the aircraft was flying. The short term on-ground exposure to CO in a serviceable aircraft was evidently not deleterious. But who knows what could happen with repeated exposure during repeated short duration ops combined with with defects in the engine bay? The science shows that CO is very ‘sticky’ in the bloodstream.
Who knows what happened in this case. At least somebody’s entertaining the possibility that it’s not all the pilot’s fault.
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Question without notice, Wingnuts: Did you have any direct or indirect involvement in the maintenance of the accident aircraft (registered as VH-NOO when the accident occurred) or then or now have any direct or indirect financial interest that would be affected by the cause/s of the accident? I declare that I don't.
[T]here is no correlation between CO exposure and CO blood levels.
Getting pax onto a seaplane and slipping mooring lines requires nifty footwork and if the pilot was affected by exposure from prior flights or burning pizzas then it would have been obvious at that stage. My question to any aviation med people (or even doctors who like carbon monoxide cases) is whether or not symptoms and debilitation are in direct proportion to blood CO content, ie., can you get a 'safe amount' of blood CO beyond which things begin to fall apart ?
Getting pax onto a seaplane and slipping mooring lines requires nifty footwork and if the pilot was affected by exposure from prior flights or burning pizzas then it would have been obvious at that stage. My question to any aviation med people (or even doctors who like carbon monoxide cases) is whether or not symptoms and debilitation are in direct proportion to blood CO content, ie., can you get a 'safe amount' of blood CO beyond which things begin to fall apart ?
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If carbon monoxide is the cause then, If a side window was opened for the camera, that would lower cabin pressure, which would increased air flow from the engine holes.
When I flew a Beaver 50 years ago, I was told not to open cockpit side window in flight if possible. Due to possible carbon monoxide leaks.
When I flew a Beaver 50 years ago, I was told not to open cockpit side window in flight if possible. Due to possible carbon monoxide leaks.
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- pilot exposure about 2hr 20min, resulted in CO ‘elevated level’
- pax x 2 exposure about 40min, resulted in same CO ‘elevated level’
- pax x 3 exposure same 40min, resulted in nil CO
No need for ‘authoritative support’ on this one. Even Blind Freddie can see the dots don’t join up.
You're assuming that the sources, contents and volumes of airflow to which each of the POB were exposed were exactly the same. Blind Freddie wouldn't make that assumption.
Is your insurer getting nervous, Wingnuts?
Is your insurer getting nervous, Wingnuts?
Investigation number:
AO-2017-118
1. "From this, the ATSB considers the levels of CO detected were likely to have adversely affected the pilot’s ability to control the aircraft during the flight."
2. "From the above activities, the ATSB found pre‑existing cracking of the engine exhaust collector-ring, which could lead to exhaust leakage into the engine bay."
3. "Further, the ATSB found a breach in the firewall from missing bolts used to secure magneto access panels in the firewall under the instrument panel in the cabin."
(my bold text)
It seems a pretty much open and shut case?
Evidence of the gas leak provided by Australian Transport Safety Bureau. Credit: Australian Transport Safety Bureau
(From 7news report)
AO-2017-118
1. "From this, the ATSB considers the levels of CO detected were likely to have adversely affected the pilot’s ability to control the aircraft during the flight."
2. "From the above activities, the ATSB found pre‑existing cracking of the engine exhaust collector-ring, which could lead to exhaust leakage into the engine bay."
3. "Further, the ATSB found a breach in the firewall from missing bolts used to secure magneto access panels in the firewall under the instrument panel in the cabin."
(my bold text)
It seems a pretty much open and shut case?
Evidence of the gas leak provided by Australian Transport Safety Bureau. Credit: Australian Transport Safety Bureau
(From 7news report)
Investigation number:
AO-2017-118
1. "From this, the ATSB considers the levels of CO detected were likely to have adversely affected the pilot’s ability to control the aircraft during the flight."
2. "From the above activities, the ATSB found pre‑existing cracking of the engine exhaust collector-ring, which could lead to exhaust leakage into the engine bay."
3. "Further, the ATSB found a breach in the firewall from missing bolts used to secure magneto access panels in the firewall under the instrument panel in the cabin."
(my bold text)
It seems a pretty much open and shut case?
Evidence of the gas leak provided by Australian Transport Safety Bureau. Credit: Australian Transport Safety Bureau
(From 7news report)
AO-2017-118
1. "From this, the ATSB considers the levels of CO detected were likely to have adversely affected the pilot’s ability to control the aircraft during the flight."
2. "From the above activities, the ATSB found pre‑existing cracking of the engine exhaust collector-ring, which could lead to exhaust leakage into the engine bay."
3. "Further, the ATSB found a breach in the firewall from missing bolts used to secure magneto access panels in the firewall under the instrument panel in the cabin."
(my bold text)
It seems a pretty much open and shut case?
Evidence of the gas leak provided by Australian Transport Safety Bureau. Credit: Australian Transport Safety Bureau
(From 7news report)
Far from an open and shut case I would have thought?
Originally Posted by The ATSB
In addition, three out of eight bolts used to secure the magneto access panels in the firewall under the instrument panel in the cabin were also found to be missing. Any breach in the firewall can allow gases to enter the cabin from the engine bay.
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[QUOTE=FlexibleResponse;10851324]Investigation number:
AO-2017-118
1. "From this, the ATSB considers the levels of CO detected were likely to have adversely affected the pilot’s ability to control the aircraft during the flight."
2. "From the above activities, the ATSB found pre‑existing cracking of the engine exhaust collector-ring, which could lead to exhaust leakage into the engine bay."
3. "Further, the ATSB found a breach in the firewall from missing bolts used to secure magneto access panels in the firewall under the instrument panel in the cabin."
(my bold text)
It seems a pretty much open and shut case?"
Open and shut case? Your faith in investigative agencies is somewhat stronger than mine. A claim made by a report is not koran.
1. The pilot’s ability to takeoff and manoeuvre at low altitude is not consistent with being ‘adversely affected’.
- The sudden, nose dive is not consistent with elevated levels of CO. Relaxation, unconsciousness are usual.
2. The initial post crash exhaust examination did not detect a preexisting crack. That became apparent 2 years later when the CO theory was put forward.
3. The 3 hole breach in the firewall, also not noted in initial inspection, is insignificant. Besides, flow through holes would be forward from cabin into engine bay due to the low pressure induced by airflow over engine bay cowling.
What appears to have happened here is that a cause of crash has been latched onto and then reverse engineered the evidence to support. Normally, the evidence is gathered and then a deduction is made.
AO-2017-118
1. "From this, the ATSB considers the levels of CO detected were likely to have adversely affected the pilot’s ability to control the aircraft during the flight."
2. "From the above activities, the ATSB found pre‑existing cracking of the engine exhaust collector-ring, which could lead to exhaust leakage into the engine bay."
3. "Further, the ATSB found a breach in the firewall from missing bolts used to secure magneto access panels in the firewall under the instrument panel in the cabin."
(my bold text)
It seems a pretty much open and shut case?"
Open and shut case? Your faith in investigative agencies is somewhat stronger than mine. A claim made by a report is not koran.
1. The pilot’s ability to takeoff and manoeuvre at low altitude is not consistent with being ‘adversely affected’.
- The sudden, nose dive is not consistent with elevated levels of CO. Relaxation, unconsciousness are usual.
2. The initial post crash exhaust examination did not detect a preexisting crack. That became apparent 2 years later when the CO theory was put forward.
3. The 3 hole breach in the firewall, also not noted in initial inspection, is insignificant. Besides, flow through holes would be forward from cabin into engine bay due to the low pressure induced by airflow over engine bay cowling.
What appears to have happened here is that a cause of crash has been latched onto and then reverse engineered the evidence to support. Normally, the evidence is gathered and then a deduction is made.
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