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Avgas quality concerns ... helicopters

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Avgas quality concerns ... helicopters

Old 30th Sep 2018, 01:47
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Avgas quality concerns ... helicopters

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Old 30th Sep 2018, 02:42
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Folks,
The reported lack of interest, let alone action, mirrors the Avgas crisis of 1999.
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Old 30th Sep 2018, 04:35
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From memory, Mobil's response at the time was much more proactive than Viva's has been to date.
https://www.wsws.org/en/articles/2000/01/air-j25.html
Can someone explain why they are only saying helicopters are affected?
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Old 30th Sep 2018, 04:49
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CASA response, as quoted in the ABC article:
"We are doing a lot of research in terms of fuel which is an area normally outside of our expertise and jurisdiction to better understand the fuel supply and manufacturing processes," said Peter Gibson from the Civil Aviation Safety Authority (CASA)."If [pilots] do have a rough-running engine in flight they need to be very careful with the handling of that aircraft and get it on the ground as soon as possible."
I totally fail to understand why CASA states that a critical input to aviation safety, fuel, is "an area normally outside of our expertise and jurisdiction". Especially since CASA micro manages virtually every other aspect of aviation safety.

To put that another way, CASA specifies in detail how and how much fuel a pilot must load and carry and manage consumption, yet there is no concern given to the possibility that the fuel itself is substandard???? This defies belief. There is a chain of responsibility leading from the refinery to the aircraft engine combustion chamber, yet CASA only wishes to micromanage part of the chain (complete with draconian penalties for non compliance) but gives the fuel companies a free pass. Why aren't fuel companies and their staff facing criminal penalties right now? It's only fair.
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Old 30th Sep 2018, 05:06
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an area normally outside of our expertise and jurisdiction
Of course it is, we see proof regularly. See how you get on if caught running your non STC'ed engine on mogas. Does CASA actually know anything? Can I fly my lighty if the temp exceeds 40°C yet? CAO 20.9
3.1 The pilot in command of an aircraft shall ensure that the aircraft is not flown unless the aviation fuel, aircraft engine lubricating oil, aircraft engine power augmentation fluid and aircraft hydraulic system fluid used in connection with the servicing or operation of the aircraft complies with the specification and grade required or approved for the purpose by CASA.

Note 1 In respect of aircraft engine power augmentation fluid and aircraft hydraulic system fluid the specification and grade specified for a particular purpose in a manual or manuals promulgated by the aircraft or aircraft engine manufacturer may be considered as having been approved by CASA.
Note 2 The pilot in command may assume that:

(a) aviation fuel; and
(b) aircraft engine lubricating oil; and
(c) aircraft engine power augmentation fluid; and
(d) aircraft hydraulic system fluid in the aircraft, other than that which he has caused to be delivered into the aircraft, complies with the required specification and grade.
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Old 30th Sep 2018, 05:13
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. I totally fail to understand why CASA states that a critical input to aviation safety, fuel, is "an area normally outside of our expertise and jurisdiction". Especially since CASA micro manages virtually every other aspect of aviation safety.
Ah yes but if they entered into fuel regulation they will have to start dealing with very well financed and politically influential Multi National Oil companies who will have the means and the finance to fight CASA at every turn. It will begin with every court case imagineable followed by backroom political pressue. Just have a look at what happens in other industries, when regulators try to regulate Multi Nationals companies.
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Old 30th Sep 2018, 05:19
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It appears at this time to be accelerated wear of piston cylinders. And only on mustering machines.
A CE in the NW tells me that they have been having issues for 12 months or so.
Indications are of high internal temps and erosion, which leads me to suspect something other than just fuel.

YPJT- There has been no issues with fixed wing aircraft operating in the same areas.

FWIW
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Old 30th Sep 2018, 05:39
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I would expect that a change made to an aviation fuel that has an adverse effect on any aircraft, is part of CAsA's responsibility.

By changing the lead content in the fuel it seems to have had an impact on the safety of helicopters used for mustering operations - I say CAsA has a responsibility to restore the safety.

I further say that to make a statement, to put it down as soon as possible is not a very good safety response from the regulator. But rather than direct the fuel back to the previous lead content until further testing is carried out, CAsA would simply suspend all mustering operations (possibly fixed wing also) until replacement engines that can operate with the new fuel are designed, tested and fitted with silly restrictions such as happened with Jabiru engines.
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Old 30th Sep 2018, 06:13
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In the previous avgas drama the recalled fuel was off loaded onto the sport/racing car enthusiast, so one of them told me. After blown engines a group got together for a class action, but the lawyers told them you don't have a hope in hell aka big, big multi national, at the time the worlds biggest.

Edited to add: https://www.casa.gov.au/file/203356/...NVBXwlewbDwqf3

Last edited by megan; 30th Sep 2018 at 06:43.
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Old 30th Sep 2018, 07:23
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Somewhat mirrors something the FAA put out recently in relation to a Falcon biz jet that suffered an all engine flame out due to the fuel not meeting standards.

Fuel standards are not developed by the regulators.
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Old 30th Sep 2018, 09:34
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Originally Posted by YPJT View Post
From memory, Mobil's response at the time was much more proactive than Viva's has been to date.
https://www.wsws.org/en/articles/2000/01/air-j25.html
Can someone explain why they are only saying helicopters are affected?
YPJT,
Interesting web site to pull up that information from 1990/2000. However, the article is accurate.
My original comment about CASA involvement was based on CASA's reluctance to get involved, over a period of several years, in what, as I recall, turned out to be a quite long standing problem of EDA contamination.
It was left up to AOPA to recruit the late Prof. David Trimm, from UNSW, as an independent expert on the fuels. He very smartly got to the core of the problem.
As always, CASA is not renowned for "taking on" anybody who has the resources for a legal defense.
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Old 30th Sep 2018, 13:13
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YPJT- There has been no issues with fixed wing aircraft operating in the same areas.
indulge my ignorance but aren't they essentially the same engines?
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Old 30th Sep 2018, 13:28
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YPJT - yes and very much no.

Choppers don't have the same airflow for cooling.
A fixed wing is cooled during landing, a chopper the opposite - mustering is not high power but not high cooling either.
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Old 30th Sep 2018, 18:23
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Originally Posted by YPJT View Post

indulge my ignorance but aren't they essentially the same engines?
To a large degree, yes.
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Old 30th Sep 2018, 20:41
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Originally Posted by YPJT

indulge my ignorance but aren't they essentially the same engines?
I,m just guessing here but aren't helicopters run pretty hard particularly when mustering. The lead in the fuel is to prevent detonation which is most likely to occur in hot conditions and at high power conditions. Reducing the lead content reduces the octane rating. With helicopters it might have been a tad too far.
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Old 30th Sep 2018, 22:43
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Originally Posted by rutan around View Post
I,m just guessing here but aren't helicopters run pretty hard particularly when mustering. The lead in the fuel is to prevent detonation which is most likely to occur in hot conditions and at high power conditions. Reducing the lead content reduces the octane rating. With helicopters it might have been a tad too far.
You have nailed the issue.
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Old 1st Oct 2018, 00:05
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While I don't fly helicopters nor do mustering I have been told that during mustering mostly it is not high power used. Lots of manoeuvring yes, but cows don't run very fast.

Detonation I would expect would cause damage to the pistons (holes), what seems to be reported is accelerated wear of the cylinders. I assume this wear is the sidewalls and/or piston rings possibly valves, guides and seats could be included.

So I think it is something other than detonation.

Is the issue similar across carburettor and fuel injected engines?

AWB 85-024 Issue 1 - points to exhaust and guide as the area of damage and wear.
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Old 1st Oct 2018, 00:29
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The other difference, is that in a fixed wing, if the engine coughs and stops momentarily, the windmilling propellor turns the engine over and allows it to fire again.

In an Uptycopter, there is a freewheel unit that does not allow the rotor to drive the engine, so if it coughs and stops, you are on the way down with probably no time to try a restart. You need altitude to establish an autorotation, left hand off the collective, crank the starter switch, with no spare hand to manipulate the throttle, unless you can get the cyclic between your knees. Very unforgiving of fuel contamination, starvation, or poor quality.
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Old 1st Oct 2018, 03:33
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AWB 85-024 Issue 1 - points to exhaust and guide as the area of damage and wear.
This sounds like too much heat to me and lends strength to the idea that the fuel doesn't have enough lead in it. An often misunderstood area of spark ignition combustion is how lead works to prevent / reduce knocking. People think it slows the burn rate down. Actually it slows down the start of burning after the ignition spark.(Ignition lag) Once the burn gets going it burns at the same rate as unleaded fuel.(Think of starting a damp campfire and a dry one. The damp one is slow to start but once going properly it burns the same as the dry one) This reluctance to start burning delays the start of auto ignition we call knocking.

If an engine is timed for fuel with a particular amount of lead and then a new fuel with less lead is used, then the timing will be wrong. The quicker ignition of the low lead fuel will have the same effect as advancing the timing. Advancing the timing means peak cylinder pressure occurs earlier and transfers excessive heat and pressure to the cylinder,piston and valves. If it goes on long enough it will do internal damage.

Some engines are more forgiving than others when it comes to timing range but a hard working one with barely adequate cooling probably not so much.ignition lag. [ig′nish·ən ‚lag] (mechanical engineering) In the internal combustion engine, the time interval between the passage of the spark and the inflammation of the air-fuel mixture. Also known as ignition delay.
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Old 1st Oct 2018, 04:32
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rutan - I was taught that lead also assisted in heat removal by the unburnt fuel air mixture out of the cylinder.

It appears that for some reason the exhaust valve and its guide area are now getting and remaining hotter than they use to, given that it is not just Lyco' but also PMA cylinders and even TCM's. I can only conclude that it is pilot error in operation of engines. ( I have my AWI interview next week).
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