Fuel icing (avgas)
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Fuel icing (avgas)
There appears to be a huge variation in the susceptability of different aircraft types to this problem.
The Aztec has been widely reported as very like to do it, so pilots flying in low temps add Prist or some other stuff.
However I have never heard of a fuel icing incident on the TB20/21 and they use the same engine (IO-540) crucially with the same fuel distribution spider on top which one would logically think must be the weakest point as the very thin steel fuel pipes (leading to the injectors) are exposed to the full high speed flow of outside air.
Can anybody supply any input on this, and also indicate whether the engine(s) failed smoothly, or failed as if with some cylinders still operating for a while.
The Aztec has been widely reported as very like to do it, so pilots flying in low temps add Prist or some other stuff.
However I have never heard of a fuel icing incident on the TB20/21 and they use the same engine (IO-540) crucially with the same fuel distribution spider on top which one would logically think must be the weakest point as the very thin steel fuel pipes (leading to the injectors) are exposed to the full high speed flow of outside air.
Can anybody supply any input on this, and also indicate whether the engine(s) failed smoothly, or failed as if with some cylinders still operating for a while.
Last edited by IO540; 2nd Dec 2009 at 11:30.
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You need to refer to the POH for each aircraft and also to the SBs issued as to whether or not you can add isopropyl or Prist (be very careful it is toxic).
I am more familiar with the Continental IO-520, TSIO-520 and GTSIO-520 engines installed in Cessna aircraft and on certain models you should add ISOP in accordance with % stated in POH.
My 'rough' rule of thumb in the 70s when flying in Western Europe, as per hangar heating, use it from 1st Oct to end March and that should solve the problem.
This problem arose in the early 70s, mainly in Europe and then further information was forthcoming from other countries such as Canada. Operators were reluctant to write about it as there was no published solution.
Trials were carried out using T310 / 340 aircraft with some tanks having ISOP and others not. When the problem was really bad a change to a tanks with 100L and more than plenty of ISOP cured the problem.
One of the first indications was a reduction in EGT with a rough imbalance on one or more engines. The problem was in the fuel manifold spider on top of the engine in that ice would restrict the flow to certain cylinders so they would run lean of peak. The larger centre avionics panel on a C402 could vibrate in sympathy, 310s didn't as the panel was more rigid. Eventually the flow to several cylinders could be restricted and the engine would cease to function sufficiently, time to go home.
Many pilots found that the only way to solve the problem was by descending to lower (warmer) altitudes, some had no option as they were unable to maintain assigned level.
The engines in later C421B and 421C aircraft had an oil feed pipe routed through the spider so this kept the temperature high enough to prevent this problem. Why other similar engines did have this feature is a question that Cessna / Continental would not answer.
If there are known problems with the IO-540 in the Aztec then perhaps others will respond.
I am more familiar with the Continental IO-520, TSIO-520 and GTSIO-520 engines installed in Cessna aircraft and on certain models you should add ISOP in accordance with % stated in POH.
My 'rough' rule of thumb in the 70s when flying in Western Europe, as per hangar heating, use it from 1st Oct to end March and that should solve the problem.
This problem arose in the early 70s, mainly in Europe and then further information was forthcoming from other countries such as Canada. Operators were reluctant to write about it as there was no published solution.
Trials were carried out using T310 / 340 aircraft with some tanks having ISOP and others not. When the problem was really bad a change to a tanks with 100L and more than plenty of ISOP cured the problem.
One of the first indications was a reduction in EGT with a rough imbalance on one or more engines. The problem was in the fuel manifold spider on top of the engine in that ice would restrict the flow to certain cylinders so they would run lean of peak. The larger centre avionics panel on a C402 could vibrate in sympathy, 310s didn't as the panel was more rigid. Eventually the flow to several cylinders could be restricted and the engine would cease to function sufficiently, time to go home.
Many pilots found that the only way to solve the problem was by descending to lower (warmer) altitudes, some had no option as they were unable to maintain assigned level.
The engines in later C421B and 421C aircraft had an oil feed pipe routed through the spider so this kept the temperature high enough to prevent this problem. Why other similar engines did have this feature is a question that Cessna / Continental would not answer.
If there are known problems with the IO-540 in the Aztec then perhaps others will respond.
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Very interesting...
You seem to have evidence (rough running) that the distribution spider (or more likely the six or so thin and exposed pipes coming out of it) really is a problem.
The spider is mounted on the crankcase, which is pretty hot. It could be that there are different mounting methods in use, with differing thermal conductivity.
A simple cure would be to put fire sleeves over the pipes...
You seem to have evidence (rough running) that the distribution spider (or more likely the six or so thin and exposed pipes coming out of it) really is a problem.
The spider is mounted on the crankcase, which is pretty hot. It could be that there are different mounting methods in use, with differing thermal conductivity.
A simple cure would be to put fire sleeves over the pipes...
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IO540
I suspect you will recall Timothy had exactly this problem over Germany I seem to recall with Iceman.
I also supect the Aztec would be more susceptible given the engines are on the wing and because it is easy to under manage the cowl flaps - which you dont have on the TB20.
As you know the amount of water in the fuel is surely a significant factor and I guess if it was a serious concern testing the fuel for dissolved water would be worth while.
I would imagine in a single with much shorter pipe runs and tightly cowled installations there is a risk but perhaps you know otherwise?
I suspect you will recall Timothy had exactly this problem over Germany I seem to recall with Iceman.
I also supect the Aztec would be more susceptible given the engines are on the wing and because it is easy to under manage the cowl flaps - which you dont have on the TB20.
As you know the amount of water in the fuel is surely a significant factor and I guess if it was a serious concern testing the fuel for dissolved water would be worth while.
I would imagine in a single with much shorter pipe runs and tightly cowled installations there is a risk but perhaps you know otherwise?
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I don't know why the Aztec should be so much more prone to fuel icing than say a TB20. The fuel pipes are much longer, yes, but those pipes are hidden inside the wings, out of the airflow.
Unless some are exposed in the wheel wells?
Unless some are exposed in the wheel wells?
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Fuel icing is more a problem at the tank, plumbing, and up to and in the fuel filter than at the fuel flow divider or injection lines/injectors.
Same reason that in very cold weather, one can't drain accumulated water from the tanks: it's already frozen.
Same reason that in very cold weather, one can't drain accumulated water from the tanks: it's already frozen.
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Fuel icing is more a problem at the tank, plumbing, and up to and in the fuel filter than at the fuel flow divider or injection lines/injectors.
Same reason that in very cold weather, one can't drain accumulated water from the tanks: it's already frozen.
Fuel icing is the freezing of water dissolved in the fuel. As British Airways know only too well, post-BA038
this happens at temperatures well below 0C.My TB20 handbook doesn' give a figure for the temp at which the additive (they give two options) should be used; they just say if flying in cold temps. But it is thought to be about -30C or lower. My coldest flight had -29C for about 2 hours (no additive).
Avgas itself freezes at about -55C but that's irrelevant. The point is that with water dissolved in it, it starts to go solid somewhere around -30C.
The question is where in the fuel system does the fuel temp fall to that level?
"Logically" it should be at the very end, because the fuel pipes are not heated anywhere so the coldest bit should be at the very end. Especially as, at the very end, you have a ~ 2ft length of a very thin (1/8" OD) steel pipe which is fully exposed to the air intake airflow.
But it could be happening further back. The flow velocity in the thin pipe will be high so the fuel will spend very little time in that pipe.
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fire sleeves are not the answer as these could then cover a leak or weep. They would also alter and possibly restrict the cooling air to the cylinders. Approval ? Major - minor Mod?
The engine manufacturer overcame the problem by routing the oil feed pipe through the spider.
Check the POH and use ISOP if approved.
It doesn't need to be particularly cold the incident in the C402B was at FL090.
The engine manufacturer overcame the problem by routing the oil feed pipe through the spider.
Check the POH and use ISOP if approved.
It doesn't need to be particularly cold the incident in the C402B was at FL090.
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fire sleeves are not the answer as these could then cover a leak or weep
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Fuel icing is the freezing of water dissolved in the fuel. As British Airways know only too well, post-BA038 this happens at temperatures well below 0C.
Fuel icing at the injectors is seldom a problem, though injectors, like spark plugs, can ice up.
Avgas doesn't suspecnd moisture like kerosine does.
You're making a ridiculous comparison when you attempt to equate any aircraft burning kerosine with any aircraft burning avgas, but more so when you attempt to equate a light piston aircraft with a large transport category airplane. The fuel systems are entirely different, as are the storage, capacity, anti-ice capabilities, and operating altitudes and subsequent temperatures attained by the fuel.
British Airways BA038 experienced ice suspended in the fuel, as turbine fuel tends to suspend moisture very well, and the most common source of fuel icing in turbine equipment is on the fuel filter. In the case of BA038, ample icing caused blockage of the fuel heaters exchangers as well, which ultimately caused the loss of power. Certain turbine engines are also very susceptible to icing of the fuel control unit, which can cause power rollbacks, runaway power, or frozen power, as well as disable certain safety features of the engine such as overspeed protection.
In a small piston engine, the fuel system is very different, and ice isn't typically suspended in the fuel. It tends to fall out in suspension, and while filter clogging does occur, icing beyond the filter into the fuel flow divider and nozzles is not at all common.
Products such as HEAT and PRIST use alcohol and other chemicals to "absorb" water as well as serve a two fold purpose to prevent ice, and to prevent microbial formation in the tanks. They can also be damaging to fuel bladders, fuel lines, gaskets, etc...and must be used very carefully and in strict accordance with the manufacturer recommendations.
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SNS3Guppy says icing beyond the filter into the fuel flow divider and nozzles is not at all common.
Oh yes it is!
Common enough for Cessna to include instructions for its use in the GAMA format POH of T310, 340A, 402C, 404, 414A and 421C aircraft. If you have ever experienced it and realised that you didn't add ISOP it concentrates the mind, well maybe not yours but it did mine!
Oh yes it is!
Common enough for Cessna to include instructions for its use in the GAMA format POH of T310, 340A, 402C, 404, 414A and 421C aircraft. If you have ever experienced it and realised that you didn't add ISOP it concentrates the mind, well maybe not yours but it did mine!
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Common enough for Cessna to include instructions for its use in the GAMA format POH of T310, 340A, 402C, 404, 414A and 421C aircraft.
Where in the flight manual are you finding an emergency procedure or abnormal procedure for ice clogging the fuel flow divider or injector nozzles? You're not? Didn't think so, as it's not there.
Where in the flight manual are you finding a requirement for flight in cold weather, or flight into known icing conditions, to use a fuel additive? You're not finding that requirement? Didn't think so, as it's not a requirement.
Now, Cessna does provide direction on concentration of additives in certain cases, if you intend to use them. The use is not mandatory, nor is icing at the injector nozzles a big problem.
In turbine equipment, suspended ice and moisture in the fuel is a problem, but then turbine fuel suspends moisture very well. Avgas does not.
The icing potential in your piston airplane is certainly there if you allow moisture in the fuel by not draining the tanks. The best way to eliminate this is by preheating the entire aircraft; best done by the use of a heated hangar overnight. This enables you to drain moisture before it freezes in the tanks. You can also wait at least a half hour after fueling to allow moisture to settle, if it's there, and drain the tank during that time and after that time.
The use of anti-icing additives is also an option, though not often used, with avgas.
If you've developed moisture in your fuel and it doesn't settle out and get drained or frozen on the bottom of the tank, it's going to be a problem with blockage of the fuel drain ports in the tank (where fuel drains into the fuel system on the way to the engine), at the selector valve, or at the gascolator/fuel filter. The fuel filter generally does not admit moisture and certainly doesn't pass ice...which means that the ice has no means in most cases of becoming an issue at the fuel flow divider or fuel nozzles. If the ice has formed in the system somewhere, it seldom has any opportunity to pass beyond the filter, to the engine fuel system.
Ice, therefore, is a much bigger problem to the airframe fuel system, than the engine fuel system.
If you have ever experienced it and realised that you didn't add ISOP it concentrates the mind, well maybe not yours but it did mine!
Where anti-icing additive is useful is in equipment left out overnight, or allowed to cold soak, or flown for extended periods in very cold climates...in times when there is never an opportunity to heat the airplane and drain water. The hope in adding the prist, heat, or other chemical is to absorb water and allow it to pass through filters and be burned, rather than icing in the tank and causing blockage of drain ports, fuel lines, selector valves, or the filter.
Icing beyond the filter is seldom, if ever, an issue.
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Sorry, just had my attention called to this.
I fly to very cold places in my Aztec, as some of you may know. My experience is that if you are going to expose the Aztec to -15C for more than 4 hours or -20C for more than 3 hours you must use 1% IPA to prevent engine failure.
IPA can be bought of eBay for approximately the same price as Avgas, so there is no huge problem with expense.
The flight that Peter was referring to was from Stockholm to Biggin. We had already been to Svalbard, and I had religiously used IPA, but I thought, wrongly as it turned out, that Bromma/Biggin in April would be OK.
One engine failed over northern Jutland and I made an immediate emergency landing on the grounds that if one engine had failed the other would follow suit. Luckily we were only 8 miles from a major airfield (I forget which now) so I did s-bends, and one orbit, down the ILS from F100. The failed engine picked up at the freezing level, which was about 3000' from memory.
The issue is ice crystals in the fuel filters. I have no idea why the Aztec is peculiarly susceptible, presumably the location of the filters or pipes that lead to them.
If you are a member of PPL/IR you can read an article I wrote on the subject. If you are not a member, it is worth joining for many such articles!
I fly to very cold places in my Aztec, as some of you may know. My experience is that if you are going to expose the Aztec to -15C for more than 4 hours or -20C for more than 3 hours you must use 1% IPA to prevent engine failure.
IPA can be bought of eBay for approximately the same price as Avgas, so there is no huge problem with expense.
The flight that Peter was referring to was from Stockholm to Biggin. We had already been to Svalbard, and I had religiously used IPA, but I thought, wrongly as it turned out, that Bromma/Biggin in April would be OK.
One engine failed over northern Jutland and I made an immediate emergency landing on the grounds that if one engine had failed the other would follow suit. Luckily we were only 8 miles from a major airfield (I forget which now) so I did s-bends, and one orbit, down the ILS from F100. The failed engine picked up at the freezing level, which was about 3000' from memory.
The issue is ice crystals in the fuel filters. I have no idea why the Aztec is peculiarly susceptible, presumably the location of the filters or pipes that lead to them.
If you are a member of PPL/IR you can read an article I wrote on the subject. If you are not a member, it is worth joining for many such articles!
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Guppy you seem to take pleasure in denegrating the experience of others and quote:
Where in the flight manual are you finding an emergency procedure or abnormal procedure for ice clogging the fuel flow divider or injector nozzles? You're not? Didn't think so, as it's not there. AND ON and ON.
Guppy. The problems encountered by others are quite clearly stated in following manuals.
C414A POH D1584-13 Section 8 pages 8-9,8-10 and 8-11
1980 model NO oil heated fuel manifold.
C4121C POH D1618-13 Section 8 pages 8-14,8-15,8-15
1985 model WITH oil heated fuel manifold.
As it is in other Cessna POHs.
Whilst Section 8 Airplane handling, servicing and maintenance is NOT mandatory and everything doesn't warrant inclusion in the Emergency Procedures Section 3.
Cessna do state " It is wise to follow a planned schedule of lubrication and preventative maintenance based on CLIMATIC AND FLYING CONDITIONS ENCOUNTERED IN YOUR LOCALITY" my caps. As you state ALL of your flying has been based in a mountain area where it is cold and freezing. Others who read the forum do live in other parts of the world and fly in different climatic conditions.
Cessna wouldn't have added it to the POH if there wasn't a problem. TCM wouldn't have incorporated the heated manifold on the 421C if there wasn't customer feedback.
Where in the flight manual are you finding a requirement for flight in cold weather, or flight into known icing conditions, to use a fuel additive? You're not finding that requirement? Didn't think so, as it's not a requirement.
Now, Cessna does provide direction on concentration of additives in certain cases, if you intend to use them. The use is not mandatory, nor is icing at the injector nozzles a big problem.
Guppy, READ THE MANUAL who mentioned flight in cold and known icing?
The manual states: One exception to this can be encountered conditions of High Humidity on the ground followed by flight to high altitude where low temperatures will exist.
It is the combination of Humidity and Cold.
If you have never experienced the incident then it has not been a problem for YOU but IT HAS been a problem for others and IT COULD be a problem for your students if they then fly where they may encounter the combination of Humidity and Cold. Before their next check ride they MAY encounter the problem.
The owners of the T310 flying at night from UK to Belgium DID have a problem with both engines but fortunately descended over The Channel. Their feedback started the ball rolling and OTHERS have encountered the problem that is why Cessna responded quickly, carried out the testing and incorporated the recommended advice in the POH.
Guppy
If you have just uplifted fuel prior to departure then you cannot drain the sumps and there is the possibility of an unknown amount of water in the system, Now how are you going to get rid of that as it can exacerbate the problem?
You are obviously a highly experienced instructor and 'check airman' whatever that is on the type with mega millions of hours, however I would have thought that, rather than denigrate what others say, a more professional and reasoned approach would have been for you to read the POH with an 'Open Mind', review ALL of the POH with your students and point out that, in your decades of worldwide experience on Cessna 400 series aircraft, you have NEVER experienced such a problem but, as stated in the manual others may have. If you choose not to carryout a complete review of the POH with your students then that a decision for you to make, perhaps you're too busy flying.
You've been there, done that and got the tea shirt, I've been there, done the testing and like many others got icing.
Guppy come down off your mountain, appreciate and understand that there are others throughout the world that may have had experiences that you may not yet had, and you may never encounter.
Where in the flight manual are you finding an emergency procedure or abnormal procedure for ice clogging the fuel flow divider or injector nozzles? You're not? Didn't think so, as it's not there. AND ON and ON.
Guppy. The problems encountered by others are quite clearly stated in following manuals.
C414A POH D1584-13 Section 8 pages 8-9,8-10 and 8-11
1980 model NO oil heated fuel manifold.
C4121C POH D1618-13 Section 8 pages 8-14,8-15,8-15
1985 model WITH oil heated fuel manifold.
As it is in other Cessna POHs.
Whilst Section 8 Airplane handling, servicing and maintenance is NOT mandatory and everything doesn't warrant inclusion in the Emergency Procedures Section 3.
Cessna do state " It is wise to follow a planned schedule of lubrication and preventative maintenance based on CLIMATIC AND FLYING CONDITIONS ENCOUNTERED IN YOUR LOCALITY" my caps. As you state ALL of your flying has been based in a mountain area where it is cold and freezing. Others who read the forum do live in other parts of the world and fly in different climatic conditions.
Cessna wouldn't have added it to the POH if there wasn't a problem. TCM wouldn't have incorporated the heated manifold on the 421C if there wasn't customer feedback.
Where in the flight manual are you finding a requirement for flight in cold weather, or flight into known icing conditions, to use a fuel additive? You're not finding that requirement? Didn't think so, as it's not a requirement.
Now, Cessna does provide direction on concentration of additives in certain cases, if you intend to use them. The use is not mandatory, nor is icing at the injector nozzles a big problem.
Guppy, READ THE MANUAL who mentioned flight in cold and known icing?
The manual states: One exception to this can be encountered conditions of High Humidity on the ground followed by flight to high altitude where low temperatures will exist.
It is the combination of Humidity and Cold.
If you have never experienced the incident then it has not been a problem for YOU but IT HAS been a problem for others and IT COULD be a problem for your students if they then fly where they may encounter the combination of Humidity and Cold. Before their next check ride they MAY encounter the problem.
The owners of the T310 flying at night from UK to Belgium DID have a problem with both engines but fortunately descended over The Channel. Their feedback started the ball rolling and OTHERS have encountered the problem that is why Cessna responded quickly, carried out the testing and incorporated the recommended advice in the POH.
Guppy
If you have just uplifted fuel prior to departure then you cannot drain the sumps and there is the possibility of an unknown amount of water in the system, Now how are you going to get rid of that as it can exacerbate the problem?
You are obviously a highly experienced instructor and 'check airman' whatever that is on the type with mega millions of hours, however I would have thought that, rather than denigrate what others say, a more professional and reasoned approach would have been for you to read the POH with an 'Open Mind', review ALL of the POH with your students and point out that, in your decades of worldwide experience on Cessna 400 series aircraft, you have NEVER experienced such a problem but, as stated in the manual others may have. If you choose not to carryout a complete review of the POH with your students then that a decision for you to make, perhaps you're too busy flying.
You've been there, done that and got the tea shirt, I've been there, done the testing and like many others got icing.
Guppy come down off your mountain, appreciate and understand that there are others throughout the world that may have had experiences that you may not yet had, and you may never encounter.
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Interesting. I didn't see you include anything from the manual which confirms your statement.
Quote it, then.
Actually, no. I stated that all my experience has been in mountainous locations...not necessarily all of it in freezing conditions. I spent several hundred hours this spring in the aircraft you identified providing instruction and acting as check airman in the desert in very hot climates, as well as in the winter in cold climates. All mountainous terrain, of course, but a variety of climactic conditions. Of course, whereas we're talking about ice, climactic conditions other than cold, freezing weather are really irrelevant...which is why I specified...cold, freezing conditions. Go figure.
You're perhaps aware that pursuing a "schedule of lubrication and preventative maintenance" has nothing to do with icing at the fuel flow divider or at the fuel nozzles.
Very well. Quote the flight manual, then. As far as what Cessna *would* or would not have done, supposition does nothing to address the issue.
Filters, yes. Why? Because they're intended to stop debris which might plug injectors (or carb jets, in the case of carbureted equipment). This includes ice; ice forming in the fuel system that makes it as far as the filter, usually goes no further. It may plug the filter and stop the engine, but by the time frozen moisture reaches the filter, it's usually unable to proceed to the engine. Hence my previous explanation(s) that most fuel system ice in aircraft using avgas is found in the tanks, lines, potentially at the selector, and finally at the gascolator/filter...but rarely if ever beyond that in the engine fuel system.
Which is precisely why one should wait a half hour after fueling to sump and sample the fuel...per authority and manufacturer recommendations.
Guppy. The problems encountered by others are quite clearly stated in following manuals.
Cessna do state " It is wise to follow a planned schedule of lubrication and preventative maintenance based on CLIMATIC AND FLYING CONDITIONS ENCOUNTERED IN YOUR LOCALITY" my caps. As you state ALL of your flying has been based in a mountain area where it is cold and freezing. Others who read the forum do live in other parts of the world and fly in different climatic conditions.
You're perhaps aware that pursuing a "schedule of lubrication and preventative maintenance" has nothing to do with icing at the fuel flow divider or at the fuel nozzles.
Cessna wouldn't have added it to the POH if there wasn't a problem. TCM wouldn't have incorporated the heated manifold on the 421C if there wasn't customer feedback.
The issue is ice crystals in the fuel filters.
Guppy
If you have just uplifted fuel prior to departure then you cannot drain the sumps and there is the possibility of an unknown amount of water in the system, Now how are you going to get rid of that as it can exacerbate the problem?
If you have just uplifted fuel prior to departure then you cannot drain the sumps and there is the possibility of an unknown amount of water in the system, Now how are you going to get rid of that as it can exacerbate the problem?
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Very well. Quote the flight manual, then. As far as what Cessna *would* or would not have done, supposition does nothing to address the issue.
You are again confusing the cause of the problem
It is the combination of Humidity and Cold.
with cold and icing.
Just take care if you ever fly in the Benelux between October and March, meanwhile safe flying.
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My experience is that if you are going to expose the Aztec to -15C for more than 4 hours or -20C for more than 3 hours you must use 1% IPA to prevent engine failure.
The issue is ice crystals in the fuel filters.
If it is the fuel filter, the way it is mounted could play a part. My fuel filter (TB20) is right underneath the fuel selector (it is all one item) and is in the belly. It is mounted against a metal surface which at a guess is 2mm thick and whose other side is the cockpit, which will be heated to say +20C. There will thus be a significant heat transfer from the cockpit into the fuel selector assembly.
Whether this will be significant to the icing issue would depend on how fast the fuel carries the heat away. Any liquid is pretty damn efficient at doing that, and at say 10GPH (typical fuel flow at high altitude) the flow velocity is about 0.4m/sec (6mm ID tube) which is a LOT.
OTOH if the Aztec (whose fuel system I know nothing about) had its fuel filter(s) mounted against a non-heated part of the hull, that could make all the difference.
The only way to settle this would be a complex temperature collection measurement in flight, which is fiddly (multiple PT100 sensors etc) and awfully hard to do legally...
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You are again confusing the cause of the problem
It is the combination of Humidity and Cold.
with cold and icing.
It is the combination of Humidity and Cold.
with cold and icing.
What I have missed is someone showing where the flight manual dictates that fuel flow divider and fuel filter icing is a big problem, as some here have suggested.
Several have contested the assertion that the lions share of icing in avgas powered airplanes takes place in the tank, lines, selector, and gascolator...not in the engine fuel system. Let them, therefore, show. Specific models of aircraft have been called out, and I reviewed the flight manuals for those aircaft before posting...and would like those who suggest Cessna shows a requirement for anti-icing fluid to post the quote, show the page, do something other than allude to preventative maintenance and lubrication. This requirement won't be found in aircraft limitations, because it isn't one. It won't be found in procedures, because there aren't procedures developed for iced fuel flow dividers or injectors, and it's not even an abnormal procedure.
Perhaps the best the posters can do is allude to an authorization by the manufacturer allowing the use of certain fuel additives, and specifying the minimum and maximum concentrations at which those additives are allowed.
This overlooks, then, the important issue of where the fuel contamination is to be found, it's effects, and the need to ensure it's removal...to say nothing of the mechanism or import of fuel additives themselves.
To overlook these things is to miss a big part of the picture needed to operate safetly, and if one operates while overlooking the important aspects of fuel icing, then one does so dangerously, and in ignorance.
What "Cessna would do" or "Cessna wouldn't do" isn't really the direction one should lean when addressing an operational issue. Only what IS.
For those citing their AFM's and POH's, then...why not site what IS...and show the text to which you refer?
Join Date: Jan 2004
Location: UK
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Guppy from your postings one can surmise that you assume that if, in your mega millions of hours flying around the world, you have never experienced the event that it has never happened to others. It is written in the manuals and one day an insurance guy may just come knocking on your door and deny a claim as you failed to adhere the manufacturer's data published in the POH. It's all in there to be read and taken into consideration.
Safe flying but make sure you have enough payload remaining for your ego.
Safe flying but make sure you have enough payload remaining for your ego.
