Airframe icing?

[SteveFSX/P3D]

Anyone experienced this? ....pretty sure I fell foul of this last night. Does this sound like airframe rather than prop ice?

I was in the A2A Comanche flying using ASN in horrendous IMC at low temps in Washington. My error was probably letting the ATC keep me in the IMC too long after a couple of missed approaches - and whilst enroute to Spokane as an alternate for the ILS approach. So maybe I was in cloud and mist at -5 for around 80 mins. I should have asked for a higher altitude ... right?

My speed started degrading (my pitot heat was on) but my engine MP/RPM remained high, temps were good on the engine. I was checking my wheels/flaps were up, thinking what's going on here? ...... the air sounded a bit different on the airframe - again making me check wheels flaps. I noticed the stall warning light was giving the odd flicker without noise - despite being above stall speed. A bit later at around 80-90 knots the nose just pitched forward and I dropped straight to the ground.

It was a pretty cool moment, and I only started realising what was going on until after the fireball. :-)

[pirateinparadise]

Haha... I love that last line.

[Ken "Hondo" Gardner]

It's called iceing on the wings, when it happens the wings lose the ability to generate lift. The ice build up creates drag and adds wieght and the aircraft responds to gravity in a big and messy manner. Wing de-icers help prevent ice build-up which starts on the leading edge of wing and tail surfaces.

[SteveFSX/P3D]

Originally posted by KenGardner:

It's called iceing on the wings, when it happens the wings lose the ability to generate lift. The ice build up creates drag and adds wieght and the aircraft responds to gravity in a big and messy manner. Wing de-icers help prevent ice build-up which starts on the leading edge of wing and tail surfaces.

Responding to gravity in a big way describes it exactly Ken. It was like the wings were gone. I'm just surprised I had never done this before in FSX. It must take a lot of idiocy for a long time in FSX :-)

[APUtech]

A2A and a few of the other payware airplanes (and a few freeware ones) do model carburetor and wing icing. The default FSX airplanes don't (at least none of mine ever have), but there was a freeware add-on I d/l'd several years ago that simulated icing on all of the default planes, wing icing (invisible) for jets and turboprops and carburetor/wing icing for non-turbo piston airplanes. I think it's in my vanilla FSX. I'll have to see if I can find it, if anyone is interested. ;-)

APUtech

[SteveFSX/P3D]

Originally posted by APUtech:

A2A and a few of the other payware airplanes (and a few freeware ones) do model carburetor and wing icing. The default FSX airplanes don't (at least none of mine ever have), but there was a freeware add-on I d/l'd several years ago that simulated icing on all of the default planes, wing icing (invisible) for jets and turboprops and carburetor/wing icing for non-turbo piston airplanes. I think it's in my vanilla FSX. I'll have to see if I can find it, if anyone is interested. ;-)

APUtech

Maybe that's why it never happened to me before APU. Most of my time being in Stock and Carenado. I have had the carb icing many times on the Comanche when running without heat. I sat before t/off recently making sure the engine was warmed and cylinder head temp was in green but still got carb ice on the climb. This surprised me as I thought the climb would prevent this but it did not.

[Ken "Hondo" Gardner]

Good old carb iceing I've this happen on both the DC3 & Gruman Goose (stock aircraft). If one looks at the throttle quandrant there are 2 extra levers labeled " Carb Heat " pulling these levers down turns the carb air heaters ON thus heating the air that is ducted into the carbs. Carbs have their own air ducting system

[APUtech]

Originally posted by KenGardner:

Good old carb iceing I've this happen on both the DC3 & Gruman Goose (stock aircraft). If one looks at the throttle quandrant there are 2 extra levers labeled " Carb Heat " pulling these levers down turns the carb air heaters ON thus heating the air that is ducted into the carbs. Carbs have their own air ducting system

Ken, really? Wow, I guess it figures that two of the default airplanes that I've flown the least are subject to icing (ironic ;-) ). Never have I flown either of those airplanes in icing conditions--in fact, I haven't flown either of them in FSX:SE.

[APUtech]

Originally posted by Steve Mak:

Originally posted by APUtech:

A2A and a few of the other payware airplanes (and a few freeware ones) do model carburetor and wing icing. The default FSX airplanes don't (at least none of mine ever have), but there was a freeware add-on I d/l'd several years ago that simulated icing on all of the default planes, wing icing (invisible) for jets and turboprops and carburetor/wing icing for non-turbo piston airplanes. I think it's in my vanilla FSX. I'll have to see if I can find it, if anyone is interested. ;-)

APUtech

Maybe that's why it never happened to me before APU. Most of my time being in Stock and Carenado. I have had the carb icing many times on the Comanche when running without heat. I sat before t/off recently making sure the engine was warmed and cylinder head temp was in green but still got carb ice on the climb. This surprised me as I thought the climb would prevent this but it did not.

Steve, carb icing can occur anytime--even on warm days--when there is a higher level of humidity/moisture in the air. A typical icing scenario is flying through very humid air, clouds during a descent, or in rainy skies. I remember a warm, hazy and overcast day in August when I was flying back from KIPL in my Piper Cherokee, and as I started my descent to Gillespie (KSEE) my engine started "missing." I had set my rpm to 1800 after I had trimmed out, but when I looked at the gauge it read just under 1700 and was still ticking down. I pushed the throttle forward for 2000 and the rpm needle moved upward but stuck at about 1750. I had skipped an item on my descent checklist--carb heat ON.

Activating carb heat allows warm, unfiltered air to enter your airplane's carburetor, so it's not normally activated when you're sitting on the ground--dirt and other debris can get into the carburetor and really foul things up--especially during runup and throttle-up for takeoff.

A constant panel scan during flight is your best friend.

APUtech

[Ken "Hondo" Gardner]

APUtech is right on !!!!

[SteveFSX/P3D]

Originally posted by APUtech:

Originally posted by Steve Mak:

Maybe that's why it never happened to me before APU. Most of my time being in Stock and Carenado. I have had the carb icing many times on the Comanche when running without heat. I sat before t/off recently making sure the engine was warmed and cylinder head temp was in green but still got carb ice on the climb. This surprised me as I thought the climb would prevent this but it did not.

Steve, carb icing can occur anytime--even on warm days--when there is a higher level of humidity/moisture in the air. A typical icing scenario is flying through very humid air, clouds during a descent, or in rainy skies. I remember a warm, hazy and overcast day in August when I was flying back from KIPL in my Piper Cherokee, and as I started my descent to Gillespie (KSEE) my engine started "missing." I had set my rpm to 1800 after I had trimmed out, but when I looked at the gauge it read just under 1700 and was still ticking down. I pushed the throttle forward for 2000 and the rpm needle moved upward but stuck at about 1750. I had skipped an item on my descent checklist--carb heat ON.

Activating carb heat allows warm, unfiltered air to enter your airplane's carburetor, so it's not normally activated when you're sitting on the ground--dirt and other debris can get into the carburetor and really foul things up--especially during runup and throttle-up for takeoff.

A constant panel scan during flight is your best friend.

APUtech

Thanks APU that's really informative. I will keep an eye on the engine output more. I should have realised this as a FSX training book I use supplied flight profiles for the FSX Moonie - with expected speeds, and power settings for each part of the flight - high cruise, level approach, descent. etc. They said the benefit of learning the profiles is that you know when something is wrong quicker. During the lessons It was very easy to see that the flaps and wheels were in the wrong position because you did not get the expected speed listed on the profile. I realise now that I should figure out profiles for the Comanche and get to know them.

Another thing I noticed when in a descent with that Comanche through bad weather (this time carb heat on) I noticed the cylinder head temp gauge was dipping below green on descent because of low engine settings. I could not think of anything to do but lower the wheels to allow a higher setting of the engine MP. Also I don't know if this low cylinder temp was a problem, or what problem it could cause with carb heat on.

[Ken "Hondo" Gardner]

Check the cowl flaps they control air flow into the engine compartment

[APUtech]

Thanks APU that's really informative. I will keep an eye on the engine output more. I should have realised this as a FSX training book I use supplied flight profiles for the FSX Moonie - with expected speeds, and power settings for each part of the flight - high cruise, level approach, descent. etc. They said the benefit of learning the profiles is that you know when something is wrong quicker. During the lessons It was very easy to see that the flaps and wheels were in the wrong position because you did not get the expected speed listed on the profile. I realise now that I should figure out profiles for the Comanche and get to know them.

Another thing I noticed when in a descent with that Comanche through bad weather (this time carb heat on) I noticed the cylinder head temp gauge was dipping below green on descent because of low engine settings. I could not think of anything to do but lower the wheels to allow a higher setting of the engine MP. Also I don't know if this low cylinder temp was a problem, or what problem it could cause with carb heat on.

*************************************************************************************************************

Steve, when your cylinder temps were low what were your mixture and prop settings? I ask about mixture because if you're running rich of peak and there's extra fuel in your cylinders, this aids in cooling the engine. Sometimes you can run your engine(s) lean of peak and that can/will increase your CHT (cylinder head temperature) and keep it in the green if the temp(s) start to drop out of the green. I own 4 A2A airplanes and they all behave very, very close to their real-world counterparts, so try experimenting with your in-flight settings: Prop, MP, Mixture, and like Ken Gardner mentioned, Cowl Flaps.

Speaking of cowl flaps, if the OAT is around freezing and below during the descent phase of my flight, I check the CHT and adjust the Cowl Flaps (closing to about 10% or so for example), MP, and RPM until I'm indicating about halfway into the green arc of the CHT gauge, unless doing so affects other systems negatively, in which case I make adjustments to get nominal indications on the critical gauges.

If I'm on the ground and taxiing to the runup area on a warm, humid, or hot day, or waiting in a long queue behind other airplanes, I'll have the cowl flaps wide open, and keep them there until I've leveled out and settled into cruise configuratiion, whereupon I either close them completely or leave them narrowly open depending on the engine temps and OAT. I do prefer them closed whenever practicable because in some airplanes that I've flown they can add drag and reduce airspeed--at least in my cases--by as much 5 knots. True, 5 knots isn't all that much, but if you're renting an airplane those 5 knots mean more time in the air which translates to a higher bill when you return the aircraft to the FBO/flight club, in addition to more fuel that you've burned. I make it a habit of topping off the tanks after I've tied down so that the flight club doesn't have to; the price that they charge you can be as much as a $1.20/gal more than what you pay to have the fuel truck tank you up.

Steve, I'm really jazzed that you're taking such an in-depth interest in aircraft systems and the various phases of flight. It will only add more realism and immersion to your experience and give you a 20/20 view of just how awesome simming can be when you apply all of the real-world information available to you.

Happy flying,

APUtech

[SteveFSX/P3D]

Originally posted by APUtech:

Thanks APU that's really informative. I will keep an eye on the engine output more. I should have realised this as a FSX training book I use supplied flight profiles for the FSX Moonie - with expected speeds, and power settings for each part of the flight - high cruise, level approach, descent. etc. They said the benefit of learning the profiles is that you know when something is wrong quicker. During the lessons It was very easy to see that the flaps and wheels were in the wrong position because you did not get the expected speed listed on the profile. I realise now that I should figure out profiles for the Comanche and get to know them.

Another thing I noticed when in a descent with that Comanche through bad weather (this time carb heat on) I noticed the cylinder head temp gauge was dipping below green on descent because of low engine settings. I could not think of anything to do but lower the wheels to allow a higher setting of the engine MP. Also I don't know if this low cylinder temp was a problem, or what problem it could cause with carb heat on.

*************************************************************************************************************

Steve, when your cylinder temps were low what were your mixture and prop settings? I ask about mixture because if you're running rich of peak and there's extra fuel in your cylinders, this aids in cooling the engine. Sometimes you can run your engine(s) lean of peak and that can/will increase your CHT (cylinder head temperature) and keep it in the green if the temp(s) start to drop out of the green. I own 4 A2A airplanes and they all behave very, very close to their real-world counterparts, so try experimenting with your in-flight settings: Prop, MP, Mixture, and like Ken Gardner mentioned, Cowl Flaps.

Speaking of cowl flaps, if the OAT is around freezing and below during the descent phase of my flight, I check the CHT and adjust the Cowl Flaps (closing to about 10% or so for example), MP, and RPM until I'm indicating about halfway into the green arc of the CHT gauge, unless doing so affects other systems negatively, in which case I make adjustments to get nominal indications on the critical gauges.

If I'm on the ground and taxiing to the runup area on a warm, humid, or hot day, or waiting in a long queue behind other airplanes, I'll have the cowl flaps wide open, and keep them there until I've leveled out and settled into cruise configuratiion, whereupon I either close them completely or leave them narrowly open depending on the engine temps and OAT. I do prefer them closed whenever practicable because in some airplanes that I've flown they can add drag and reduce airspeed--at least in my cases--by as much 5 knots. True, 5 knots isn't all that much, but if you're renting an airplane those 5 knots mean more time in the air which translates to a higher bill when you return the aircraft to the FBO/flight club, in addition to more fuel that you've burned. I make it a habit of topping off the tanks after I've tied down so that the flight club doesn't have to; the price that they charge you can be as much as a $1.20/gal more than what you pay to have the fuel truck tank you up.

Steve, I'm really jazzed that you're taking such an in-depth interest in aircraft systems and the various phases of flight. It will only add more realism and immersion to your experience and give you a 20/20 view of just how awesome simming can be when you apply all of the real-world information available to you.

Happy flying,

APUtech

Thanks APU. The likes of yourself, Ken, and a few others on here take time to explain things, and fill in the dots from real world flying. Sometimes we sim flyers know the description of something, know where the item is, but don't really know how or when to use it properly. It's easy to ignore the detail when your life is not on the line. That's both the best bit about sim-flying and it's biggest weakness.

I realise that it's much better to learn in a smaller GA aircraft done with a lot of detail. I know there are people buying PMDG airliners who can't a fly a VOR radial in a Cessna. I know I was one of them :-)

I did not realise that connection between the CHT and the mixture when descending. I can guarantee I was running with a rich mixture on descent. I have got into the habit of leaning properly with engine noise when in climb and cruise, but just gradually increasing the mixture through guess-work when in a descent. I suppose it did not matter much with stock aircraft, but now in these detailed aircraft you find out things are connected in dangerous and meaningful ways.

In the Comanche I was descending from cruise altitude using 15-17mp / 17Rpm ... and mixture probably too rich due to advancing the control too early. Not got a clue about a proper descent profile for the Comanche, as the manual just supplies cruise profiles from what I can see. Would a higher MP and lower RPM be a better heat producing combination?

I have been using cowl flaps in some Moonie lessons, but as far as I can see they don't have them on the Comanche. In fairness I have never seen this engine heating that much - so maybe they are not needed? ..... or they are open on my aircraft and that explains the cool temps :-)

[Nightmare1964]

Ice on the wings significanly increases the stall speed of an aircraft. If you suspect icing on the wings, keep your speed well above the listed stall speed, about 1.3 above would be a safe thing. If your plane has a de-icing system, then would be a good time to use it.

Oh and checklists are your friends, isn't that right APUtech? Don't you hate skipping or missing an item, then finding out the hard way, the importance of performing that task....

[Morag]

I caught the edges of my Twin Otter windows looking a bit frosty yesterday flying from Land's End to Plymouth

http://steamcommunity.com/sharedfiles/filedetails/?id=863035500

so I thought I'd leave the heater off and see what happened, it got bad

http://steamcommunity.com/sharedfiles/filedetails/?id=863035538

really bad

http://steamcommunity.com/sharedfiles/filedetails/?id=863035582

it didn't add to my IFR hours tho