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Guest SrPilot

Cowl scoop and carb inlet query

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Guest SrPilot

As a curious type, I wonder whether anyone has installed some type of FOD protection for the cowl scoop and carb air inlet on the A22LS. I attach 3 photos - one the cowl scoop, one the inlet for the carb air, and one of the type of wire that several of us used in wing root inlets on CJ6s to keep rocks, screws, and birds out of our inlets. Best I can tell, this particular inlet on the A22LS is generally unprotected for various objects intruding into the carbs. I know of one plane of a different type that sucked what appeared to be a screw through its inlet. The object ended up in a cylinder and ruined it. A cylinder replacement was required.

 

So, as I wonder, can anyone tell me if you know of anyone protecting that inlet with screen wire or some such installation? I expect to do something unless I get some good info on why it would be a bad idea to try to keep FOD at bay. (In case it's not used in Australia, FOD in USAF parlance means Foreign Object Damage).

 

Thanks for any info!

 

1787743177_Cowlscoop.jpg.5dfa495a0de26918c442c1b1f1d130cb.jpg

 

524465035_Carbinlet.jpg.1ad8c6d4cfa3199bb6183313d3b2b421.jpg

 

high-quality-concrete-wire-mesh-panels-hog.jpg.d16d747a5a6fb94bc0c295e715e8bae2.jpg

 

 

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My inlets on the savannah go into a airbox that has a filter in it so no need for a FOD...but that looks like it goes straight into the crab...I would think that isnt good at all.....I would have some sort of FOD for sure

 

 

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Hi SrPilot - all the air, whether cold or hot, goes through the cone air filters inside the carb heat box, so no need for any wire mesh or other stuff.

 

 

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You would be crazy not to protect from FOD...$24,000 engine v $24 FORD screen / filter...

 

 

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A mesh like that unless large area is going to affect airflow. Isn't there any foam or paper filter somewhere? Nev

 

 

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A mesh like that unless large area is going to affect airflow. Isn't there any foam or paper filter somewhere? Nev

See my post above

 

 

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Settle down people.

 

It should have the standard tapered K & N filters in the airbox attached to each carb. The airbox wraps around these.

 

The pic down the inlet hole shows the round disc which is attached to a cable.

 

In the lower position, fresh cold air comes in via the scoop.

 

In the raised position the inlet to hot muffler air is exposed and the cold air shut off.

 

 

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Settle down people.It should have the standard tapered K & N filters in the airbox attached to each carb. The airbox wraps around these.

 

The pic down the inlet hole shows the round disc which is attached to a cable.

 

In the lower position, fresh cold air comes in via the scoop.

 

In the raised position the inlet to hot muffler air is exposed and the cold air shut off.

See my post above

 

 

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I put similar screens over my inlets. I didn't want any foreign objects going in there ether.

 

Haven't tried them yet though.

 

 

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Guest SrPilot
Hi SrPilot - all the air, whether cold or hot, goes through the cone air filters inside the carb heat box, so no need for any wire mesh or other stuff.

Thanks. A U.S. operator sent me a similar message today. He says there is a filter between the air box and each carb. Okay, I understand. Better to ask a question and get answers from experienced people than to tear down a new air box to see if I can find a filter (then not be able to put the puppy back together). 101_thank_you.gif.0bf9113ab8c9fe9c7ebb42709fda3359.gif

 

Now that we have settled the "no screws will get in the carb (or the engine) because of the filters at the carb intakes," let me ask another question. I'll do it based on my experience of ingesting a bird while instructing in a C150.

 

Suppose a nice sized bird flies right into the cowl inlet and stuffs it. The filters will catch any feathers before they enter the carbs, but what is the source for air into the carbs? The inlet is blocked by the bird. The filters are downstream just before the carb. Another pilot informed me today that this could not happen because the cowl would create an airflow that would direct the bird away from the inlet. Hummm. First, I reminded the pilot that I was not flying an F16. I doubt that an A22LS creates enough airflow to redirect birds that much, but let's suppose a sparrow is redirected over the top of the cabin. Great. Unfortunately, the goose flying in its wake isn't. And talking about stuffing an inlet, imagine a goose in that inlet. I doubt that the airflow across the cowl of a Foxbat would be sufficient to redirect the trajectory of the soon-to-be stuffed goose.

 

geese-flying.jpg.cdc9a534915a2cd09ecff4ae6a0518a9.jpg

 

 

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If I am ever unlucky enough to have a bird fly straight into the carby inlet scoop I think I will take it as a sign that I need some forced landing practice :) I do stuff the thing with a rag while in the hangar but that is to stop red backs and other creepy crawlies setting up house in there. I do wonder if one day I will forget to take it out before flight but as the cowl comes off during every daily it's fairly unlikely (also the rag is a remnant of some of my more flamboyant pyjamas so hard to miss )

 

On a similar theme, a good trick is to put the oil reservoir cap into the slot formed by the upper engine mounts near the firewall while checking the oil. This prevents the cap being left off as the cowl won't go back on with it there.

 

 

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Talk of bird strikes: never had one but probably most likely around us would be an eagle and if so it might be better described as a mid air collision ! If it came through the windscreen that would probably be the proverbial "that". The Foxbat does have those forward bracing struts to give some protection (notably absent in the A32).

 

 

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Thanks. A U.S. operator sent me a similar message today. He says there is a filter between the air box and each carb. Okay, I understand. Better to ask a question and get answers from experienced people than to tear down a new air box to see if I can find a filter (then not be able to put the puppy back together). 101_thank_you.gif.0bf9113ab8c9fe9c7ebb42709fda3359.gif

Now that we have settled the "no screws will get in the carb (or the engine) because of the filters at the carb intakes," let me ask another question. I'll do it based on my experience of ingesting a bird while instructing in a C150.

 

Suppose a nice sized bird flies right into the cowl inlet and stuffs it. The filters will catch any feathers before they enter the carbs, but what is the source for air into the carbs? The inlet is blocked by the bird. The filters are downstream just before the carb. Another pilot informed me today that this could not happen because the cowl would create an airflow that would direct the bird away from the inlet. Hummm. First, I reminded the pilot that I was not flying an F16. I doubt that an A22LS creates enough airflow to redirect birds that much, but let's suppose a sparrow is redirected over the top of the cabin. Great. Unfortunately, the goose flying in its wake isn't. And talking about stuffing an inlet, imagine a goose in that inlet. I doubt that the airflow across the cowl of a Foxbat would be sufficient to redirect the trajectory of the soon-to-be stuffed goose.

If your unlucky enough to injest a goose into the scoop pull the carb heat on and you will draw air from under the cowl in the heated area around the muffler

 

 

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Guest SrPilot
Talk of bird strikes: never had one but probably most likely around us would be an eagle and if so it might be better described as a mid air collision ! If it came through the windscreen that would probably be the proverbial "that". The Foxbat does have those forward bracing struts to give some protection (notably absent in the A32).

I have been curious about a "heavy" strike - eagle, buzzard, goose - into the windshield. The Lexan is rather thin and the center area is flat, not curved. A 100 mph collision with a feathered shot put might not do the windscreen any good. With a destroyed windshield, the plane would have quite different aerodynamics. Would it be flyable considering the severe disruption of airflow over the windshield, or would the horizontal stabilizer be in such turbulent air that it would be a problem? I was cleaning my windshield last week and noticed the windshield flexes when pressing lightly with a towel while removing the Plexus cleaner. I cannot remember a windscreen flexing with me before but this one probably is the first one that I've had with a large flat surface in the middle, and I am sure it is my first venture into weight saving by way of thin material. I split a GlaStar windshield once and replaced what I believe was a 1/4 inch screen with a 3/8 inch. The difference in weight was there, but I wasn't working with a 1320 pound maximum legal gross weight.

 

It's not that I'm worried about such things; I am just a naturally curious type and never like to get somewhere or into something that I haven't thought about beforehand. Besides, I really started noticing geese after seeing them up close and personal while flying an RV-3A and became even more attentive after seeing the movie The Edge. For a clip showing the goose-strike aftermath in the movie, start at 9:00 on this clip.

 

 

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The Edge. For a clip showing the goose-strike aftermath in the movie, start at 9:00 on this clip.

These guys are pvssies, if you want to crash a Beaver, do it for REAL!!!

 

(You've all probably seen this..., the movie is 'Mother Lode')

 

 

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You can get attacked by an eagle when flying a Drifter and I have had Ducks flying alongside. Don't think any of these windscreens will help you much if the bird is coming the other way and is not wary. They usually dive, which can be helpful if you are not too low. Nev

 

 

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Good on you, Sr for being cautious and proactive! Too many planes have a thin layer of fragile acrylic in front of the crew. In my experience, if well-secured, even thin lexan will resist tearing and absorb enormous impacts.

 

Once upon a time, while riding at high speed I was hit in the face by a fair-sized rock thrown up by a fast-approaching van. The impact speed would have been well in excess of 160km/hr. The curved lexan helmet visor bent in about 30mm and gave my nose a big whack, but there was no damage.

 

 

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You can get attacked by an eagle when flying a Drifter and I have had Ducks flying alongside. Don't think any of these windscreens will help you much if the bird is coming the other way and is not wary. They usually dive, which can be helpful if you are not too low. Nev

The majority of birds seem to have the cognitive ability to calculate a divergence distance to vehicles travelling at up to about 100 - 110 kph ( watch the crows, Magpies, Mynahs etc. on country roads.) Parrots do not.... Budgerigars have difficulty in counting their feet, galahs rarely know they HAVE feet, and sulphur-cresteds are hell-bent on destroying something - anything - anyway.

 

I suspect eagles have sufficient nouse ( and more than sufficient eyesight) to avoid collisions, though in the case of a Drifter, they may simply be irritated at the noise and keen to chase the damn thing out of their area before a headache sets in. If I were an eagle, I would...

 

Ducks flying alongside a Drifter? Bloody lethargic Ducks, in my opinion. Are you SURE none of them were black and lithping in a tharcathic manner? Dethpicable....

 

 

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The energy of a decent bird-strike:

 

Many years ago, 'progressing' homewards to Canberra from a weekend's gliding at Narromine, along the Lachlan Valley Highway just north of Boorowa. Mate's rather non-standard Volvo 122S, with some tasty bits of kit on it - including a brand-new, imported-from-Sweden, windscreen ( the Australian ones were too soft and pitted badly). Anybody who knows the 122 series Volvo, knows the windscreen is little more than a slit-trench firing hole.

 

For reasons which are complex, we had decided (mutually) to distance ourselves from a Police Pursuit Charger helmed by with an officer who seemed keen to sell us a ticket to some official function. Neither of us had much money in our wallets ( as one doesn't after a weekend's gliding) and credit cards were yet to come. As it happened, both of us were doing a bit of club car racing on the side, and travelling at somewhat exaggerated velocities was not an unknown experience.

 

Not to put too definitive a point on it, we were travelling at slightly in excess of the typical cruising speed of, let's say, a J230 with more fuel than daylight left to reach the target destination. About 5km north of Boorowa, a bloody sulphur-crested flew off a post on the side of the road and we hit it with the windscreen dead square in front of the driver.

 

The laminated screen was cracked beyond comprehension - from top to bottom and side to side. The bang when it hit was mega. It did NOT collapse, and by the time we actually got to Boorowa, we'd regained some composure.

 

Seriously: if you hit a bird, even just the size of a large-ish parrot, square-on with an acrylic or Lexan screen on most of our class of aircraft, it is very likely to come through any fairly flat screen, pulling the fastenings out with it, unless it is some sort of bonded-in, structural component. Lexan is far more impact-tolerant than acrylic, but neither is as good as not being in a bird-strike situation in the first place..

 

 

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Agree with that . Don't count on it doing much at all and the force would probably tale a wing or strut off some of our aircraft if a direct hit from something like a wedgetail, a species which appears to be on the increase. Good for the environment but not for us. The faster aircraft are more at risk. Double the speed and 4 times the force. Nev

 

 

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I hit a small duck at an unspecified location and speed in car... But well below cruising speed of a jab and below an older foxbat... It smashed the headlight in under the bonnet, bent the bonnet, bent the front bumper and bent the front metal guard.... $1400 damage .....and a lot of broken glass, plastic and bent metal... It looked like i hit a small kangaroo... A bird as big as a medium duck at 75 knots plus is possibly going to push a windscreen out of location on most LSA type aircraft and do substantial damage....

 

I have hit kangaroos at much lower speeds and done far far less damage.

 

It highlighted to me the extreme damage done at a bit higher speeds , even by small fluffy objects

 

relatives out Tamworth way reckon below 120 kmh most birds will be avoided, at 120 kmh plus most get hit....

 

 

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The majority of birds seem to have the cognitive ability to calculate a divergence distance to vehicles travelling at up to about 100 - 110 kph ( watch the crows, Magpies, Mynahs etc. on country roads.) Parrots do not.... Budgerigars have difficulty in counting their feet, galahs rarely know they HAVE feet, and sulphur-cresteds are hell-bent on destroying something - anything - anyway.

I suspect eagles have sufficient nouse ( and more than sufficient eyesight) to avoid collisions, though in the case of a Drifter, they may simply be irritated at the noise and keen to chase the damn thing out of their area before a headache sets in. If I were an eagle, I would...

 

Ducks flying alongside a Drifter? Bloody lethargic Ducks, in my opinion. Are you SURE none of them were black and lithping in a tharcathic manner? Dethpicable....

Loved the post Oscar. Almost wet myself. Yellow-tailed black cockatoos are even more destructive than sulphur-crested, I always think of them as the outlaw biker gang of the bird world.

 

Talking of bird's cognitive ability, one managed to land a sh*t fair in the centre of my visor while doing in the region of 160km/h heading down to Port Arthur on the VFR many years ago. I have no idea of the breed, height or angle of deflection, but I bet the bugger was chuckling to himself and boasting to his mates afterwards.

 

 

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