Sydney Seaplanes de Havilland Canada DHC-2 Beaver VH-NOO crash report update

[onetrack]

The ATSB has released an update to the above crash investigation (internal review of the final report) and has determined that carbon monoxide poisoning of the pilot led to the crash.

The Beaver had a cracked exhaust collector ring, coupled with numerous missing bolts in the firewall, leaving holes through which exhaust fumes could enter, according to the investigators.

 

It is a matter of great concern that supposedly highly-trained and qualified LAME's could allow this to happen.

The investigation report certainly sends a very strong warning to ensure your aircraft is fume-proof, and that a good CO detector is fitted.

 

The investigation is expected to be completed in the third quarter of 2020.

 

https://www.atsb.gov.au/publications/investigation_reports/2017/aair/ao-2017-118/

[phantomphixer]

Considering that the accident occurred shortly after takeoff, I have to wonder if CO poisoning has a cumulative effect on the body in a given time frame. The time for exposure would seem quite small from engine start to climb out. Could there have been residual CO in their blood from the outbound flight?

I ask this because it could be food for thought for a lot of us.

[facthunter]

The usual cause is a faulty cabin heater where the exhaust is used for the heat source. How long had it been flying since the last landing? Nev

[skippydiesel]

Onetrack "- The investigation report certainly sends a very strong warning to ensure your aircraft is fume-proof, and that a good CO detector is fitted." - For sure and in case anyone is interests you can pick up a great little unit from Bunnings AeroSpace suitable for boats, caravans, RV's, etc Depends on where you purchase but from about $35-45. Batteries good for about 5 years (then replace) Light & sound warning LED readout. Even keeps a history of max PPM.

 

I agree with Phantomphixwer - exposure time would seem to be a bit short. Unless the pilot & Pax were breathing almost pure exhaust, which seems unlikely.

[onetrack]

Carbon Monoxide is not cumulative in the body. An interesting effect, however, is that being exposed to quite low levels of Carbon Monoxide for an extended time, produces a form of "acclimatisation", which enables the individual to function without CO-caused dysfunction.

But - when the individual is removed from the constant low-level exposure to CO, and then returns to the exposure, it takes a lower level of CO exposure to affect the bodys function.

 

CO poisoning starts at very low levels (6ppm), and the initial signs are headache, dizziness and nausea, coupled with decision-making confusion. If you become severely poisoned with CO, you will suffer from long-term neurological damage.

 

https://www.karger.com/Article/PDF/24630

[Flightrite]

Quell make a 'must have' detector.

[kgwilson]

The startup, warmup and taxi probably took a lot more time than when it left Rose bay earlier. With the engine running and little forward movement exhaust fumes may be able to get into the cabin even without the holes in the firewall so the exhaust smell may be considered normal in that situation so it did not deter the pilot. I guess the problem is that when poisoning can occur at only 6ppm and the gas is colourless and odourless and the exhaust smell is normal before takeoff (I am only surmising here) the pilot and passengers were totally unaware of what could and did happen when all the holes in the swiss cheese lined up. I hope all Lames take a very hard look at their procedures to make sure they do not ever leave unplugged holes anywhere when repairs or modifications are carried out.

[Kenlsa]

I seem to remember a truck full of members attributed this crash to just about everything else but CO. Just goes to show that it is best to keep theories to yourself until firm evidence is produced

Ken

[Flightrite]

Some of us have curious minds and lead the way with questions and theories, others are followers!

The cause of the crash can be put down due to impaired decision making.

[Marty_d]

from Bunnings AeroSpace suitable for boats, caravans, RV's, etc Depends on where you purchase but from about $35-45. Batteries good for about 5 years (then replace)

10 years actually - I bought one for the house a couple of weeks ago.

[Jase T]

Take a moment to reflect on the impact of Co poisioning on the decision making process and how easy it was to end up where they did.

[Jase T]

A second comment here if I may. When was the last time you (or I or any of us) included the CO indicator as part of your scan??? It's stuck there on the panel, but when did you last look at it in flight? Do you even remember what colour means what?? I am as guilty as the next person and think we can all learn a valuable lesson form this!!!

[Flightrite]

A second comment here if I may. When was the last time you (or I or any of us) included the CO indicator as part of your scan??? It's stuck there on the panel, but when did you last look at it in flight? Do you even remember what colour means what?? I am as guilty as the next person and think we can all learn a valuable lesson form this!!!

That's very true for those that have them. I have a hard wired alarm able unit fitted with test function, I would not fly without at least a portable one.

[jackc]

A second comment here if I may. When was the last time you (or I or any of us) included the CO indicator as part of your scan??? It's stuck there on the panel, but when did you last look at it in flight? Do you even remember what colour means what?? I am as guilty as the next person and think we can all learn a valuable lesson form this!!!

A major wake up call for me.......need to get myself a good quality detector.

[Old Koreelah]

My made-in-Canada CO detector cost bugger-all. It’s powered by a 9v battery, so always sampling. Although it’s a decade old and probably due for replacement, it gets tested each flight: during warmup with cowls shut, enough nasty stuff leaks into the cockpit to register 150+ppm (and my firewall has no obvious holes, unlike the crash Beaver).

Once the aircraft starts to taxi, with cowls partly open, the reading drops to zero.

[tuffnut]

Strange days indeed.... I have spent many thousands of hours behind radial engines and experienced all sorts of exhaust problems along the way. Radials are natorious for exhaust cracks, holes, falling off, crook clamps etc etc. It is often very hard to find cracks and faults with these systems due to the visual difficulties seeing in all the nooks and crannies. (so don't be too hard on the LAMES). I have seen these exhaust systems develop really big cracks in 10 or so hours in a place a pilot would normally never see. Another issue is the lack of LAME experience with radials these days. Radial engine exhausts are full of 'slip joints' which if tightenend too tight crack the exhausts very quickly. I never heard of or experienced an incapacitation from this cause even in the time when great numbers of Beavers were accumulating many thousands of hours in super spreading. Intrinsically radials blow air, exhaust gases and oil all over the place and Beavers leak like a sieve. If enough gas could come through those couple of 1/4 bolt holes to cause that crash in the time available, then I must be addicted!! Because these old aircraft are air sieves, I never had a detector either and if I had it wouldn't have worked. Keep looking boys, there are other simpler explanations!

TN

[Thruster88]

Beavers effectively have two fire walls, the first is bolted to the back of the engine. The crack was right at the cylinder head and would not have opened up pre impact. The cooling airflow would carry any leak overboard. In the pic the exhaust has been removed from the cylinder the guy is working on. The second fire wall containing the magneto access covers is on the far left.

 

 

Hopefully the ATSB will provide all the methodology of the tests they conducted on the exemplar aircraft

[Old Koreelah]

...If enough gas could come through those couple of 1/4 bolt holes to cause that crash in the time available, then I must be addicted!...

In effect, we all are addicted to CO: because our red blood cells prefer CO to O2, it only take a low, but persistent concentration of Monoxide to displace the Oxygen till your lights go out.

[facthunter]

I'm pretty sceptical on this one. There's a (sort of) double firewall on this type of installation. Nev

[Flightrite]

I accept the CO was a contributing factor but we will never know the full reason/story. Pilots are only human, we do f**k up sometimes!

[Blueadventures]

A major wake up call for me.......need to get myself a good quality detector.

Hi Jack This is one I have fitted, it calibrates and gives reading and manual tells you what the effect / exposure time will have on us. $99 US from Aircraft Spruce. Was $150 AU when I got it. Only other type I would use that's cheaper is the long life Co detector card at about $26 AUD but I could not source any so got the dearer one.

 

[Jase T]

I accept the CO was a contributing factor but we will never know the full reason/story. Pilots are only human, we do f**k up sometimes!

Speak for self....

 

I do it often!!!!

[onetrack]

The ATSB seems to have been very thorough and very careful to ensure that the carbon monoxide toxicity tests and results were accurate, and reviewed by the appropriate health specialists.

 

The autopsy results rarely lie, and carbon monoxide is an insidious and silent gas that has incapacitated and killed many people in many different environments.

[facthunter]

No harm in having a CO meter but most incidents involve faulty cabin heaters. where the potential for lots of CO is greater. I understand being a smoker can compound the effect. Were the other occupants tested? Nev

[Flightrite]

No harm in having a CO meter but most incidents involve faulty cabin heaters. where the potential for lots of CO is greater. I understand being a smoker can compound the effect. Were the other occupants tested? Nev

 

Yr dead right there had a 'Janitrol' heater near knock 8 of us out in a 'Nevago' (PA31). We all felt lathargic and had headaches?