AR-1 accident final report from NTSB N11TG

[Abid]

This report is a very sobering reminder of every detail we need to pay attention to in aircraft. Tony Mattioli had a fatal accident in an AR-1 gyroplane (N11TG) here in Florida in 2021. Tony was a super guy and very good and capable airplane IFR and gyroplane Sport Pilot. He loved flying his AR-1 powered with a Rotax 914.
The NTSB final report points out that in the end he went down because his Rotax 914 engine quit because of water contamination in the right carb bowl. That is definitely what happened though somethings do not make sense still but certainly the engine was not running when he hit the trees and then the ground. The engine ran fine on the gas in the tank once the carb bowl was cleaned up. There was no water found in the fuel tank.
I am at a loss on how after 1.5 hours there was water in only one carb bowl when the fuel from the tank comes in one way and gets tee'd to each carb and why water would come in after 1.5 hours of flight and not right at the beginning of the flight as water should settle to the bottom where fuel pick up and fuel sample quick drain is. I know ethanol can keep water dissolved/mixed in the fuel but why would it separate 1.5 hours later???

 

[DavePA11]

Did it slowly accumulate?

 

[BEN S]

"However, with minimal places to make a forced landing in a heavily wooded state forest, it’s possible the pilot was unable to locate an area to make a forced landing safely."

I wasn't there, don't know the gentleman (rip) and am totally armchairing this one but for those of us "raised" on Mac-Attacks and Two-Strokes the mantra "Don't fly over anything you can't land on" sure was drummed into my very core.
I wonder if there wasn't a better flight profile to follow like fire trails or dirt roads or something....
Very sad.
As for the water in the Carb, is it possible carb icing that melted after the accident? I KNOW it can happen on two strokes in humid Florida....

 

[StanFoster]

Ben...You nailed it! I have watched gyro videos over solid wooded areas
..over stretches of water, over miles of urban areas with wires like spider webs...and that engine better keep running. My gyro instructor drilled into my head not to fly over anything I could not glide out of if my engine ever quit. I had 1 forced landing in an ultralight, 17 in a gyro...and 2 in a helicopter. I thanked myself in the mirror each time for that instruction.

 

[Steve_UK]

the NTSB report also shows flight path and accident location maps - not far from state road 100

 

[Abid]

"However, with minimal places to make a forced landing in a heavily wooded state forest, it’s possible the pilot was unable to locate an area to make a forced landing safely."

I wasn't there, don't know the gentleman (rip) and am totally armchairing this one but for those of us "raised" on Mac-Attacks and Two-Strokes the mantra "Don't fly over anything you can't land on" sure was drummed into my very core.
I wonder if there wasn't a better flight profile to follow like fire trails or dirt roads or something....
Very sad.
As for the water in the Carb, is it possible carb icing that melted after the accident? I KNOW it can happen on two strokes in humid Florida....

I think he would have flown much higher over this area but it was a marginal VFR day. There was a road nearby that I think he might have been trying to make it to but did not have the altitude. Also did not make sense why he went from 58 knots to 76 knots. 55 knots is best glide speed.
I have thought about carb ice. It is very likely he did d fly through some clouds on that day in that area. But 914 is a turbo charged engine with turbo generally throwing hot air into the intake. It reduces chances of carb ice a lot. But maybe.

 

[Abid]

the NTSB report also shows flight path and accident location maps - not far from state road 100

Exactly. I think he had to reduce the altitude he would normally fly at in such a location by a lot because of low clouds due to marginal VFR day. I have flown a cross country before over green swamp here when I followed him, and he had no problem going to 2500 feet and keeping some landing area within glide. He may have misjudged the weather that day in the area.

 

[Abid]

Did it slowly accumulate?

I am not sure. Generally ethanol has the ability to keep water molecules completely mixed in gasoline so it will go right through most filters and burn in the engine. It should not separate. When it does, it’s called phase separation. That usually means bad gas and/or old gas. That should not happen.
It should not in theory accumulate slowly because Rotax carbs suck gasoline from the bottom of the carb bowl.
I wonder if you put ethanol gas that has some water in your fuel tank just before flight and then don’t wait long enough to allow water to settle to the bottom before sampling fuel if that can create a false sense that your fuel has no water. Usually when I put gas in just before flight, I will wait 10 minutes before sampling fuel without moving the aircraft.
Here is a paper/memo by a chemical fuel engineering department about phase separation.
It is interesting that on this day it is highly likely that Tony did go through and was very close to low clouds/fog that developed in the area after he took off from his airport about an hour flight away. That was predicted in the weather briefing, but I am not sure Tony got the whole weather brief. He should have for a flight farther away from the airport and of 2+ hours intended. I know flight schools at our airport cancelled student cross country flights into central Florida due to MVFR concerns that day.

Excerpt:
"Phase separation, however, generally only occurs when liquid water (as opposed to water vapor) is introduced to the fuel system. If tank vents are left open, either in the engine being operated, or at a fuel distribution station, water can enter the fuel system in the form of rain (or spillage, etc.) or through the air in the form of moisture. Also, since conventional gasoline absorbs very little water, there is often a layer of water present at the bottom of a filling station tank normally used to store conventional gasoline (water is more dense than gasoline, and will therefore sink to the bottom). Before an oxygenated gasoline is added to such a storage tank for the first time (particularly ethanol-blended fuels), this water must be purged from the tank to prevent the water from removing any ethanol from the fuel. Since the solubility of water in both gasoline and air decreases with a decrease in temperature, water can enter a fuel system through condensation when the atmospheric temperature changes."

https://www.epa.gov/sites/default/files/2015-09/documents/waterphs.pdf

 

[j4flyer]

I would like to know if both carbs feed from independent lines or if they use a pass through type of fueling where one carb fills the other carb. I could see how it could happen in either situation. In the first a slug of water could be sucked up separately while in the second a gascolator situation could happen. Still, very strange. Abid in your discussions with Rotax would it be possible to ask if they encountered this before ? Thanks.

 

[Abid]

I would like to know if both carbs feed from independent lines or if they use a pass through type of fueling where one carb fills the other carb. I could see how it could happen in either situation. In the first a slug of water could be sucked up separately while in the second a gascolator situation could happen. Still, very strange. Abid in your discussions with Rotax would it be possible to ask if they encountered this before ? Thanks.

This is a Rotax engine and fuel pumps supply a distribution and pressure regulation block that tee's fuel into both carbs and regulates the pressure and send the excess fuel back to the tank via a return line. It is not the case that fuel goes through one carb and then into the other.
I am going to talk to Kodiak tech support if they have seen anything like this. I certainly have not and I worked at Searey as a contract certification engineer where they used a lot of 914s. Never heard this there as well from any 500+ customers flying Seareys.
It sounds to me that Tony had gotten some bad gas (phase separation) that had suspended water in it when he sumped the fuel probably right after putting it in. Generally, you have to wait to allow such water to settle down to sump and get a correct picture of water in fuel. Still strange that it took 1.5 hours after takeoff for it to do its thing. I would have expected within 15 to 20 minutes unless temperature dropped during flight making phase separation more.

 

[Greg Vos]

"However, with minimal places to make a forced landing in a heavily wooded state forest, it’s possible the pilot was unable to locate an area to make a forced landing safely."

I wasn't there, don't know the gentleman (rip) and am totally armchairing this one but for those of us "raised" on Mac-Attacks and Two-Strokes the mantra "Don't fly over anything you can't land on" sure was drummed into my very core.
I wonder if there wasn't a better flight profile to follow like fire trails or dirt roads or something....
Very sad.
As for the water in the Carb, is it possible carb icing that melted after the accident? I KNOW it can happen on two strokes in humid Florida....

I would like to know if both carbs feed from independent lines or if they use a pass through type of fueling where one carb fills the other carb. I could see how it could happen in either situation. In the first a slug of water could be sucked up separately while in the second a gascolator situation could happen. Still, very strange. Abid in your discussions with Rotax would it be possible to ask if they encountered this before ? Thanks.

Both are fed from a fuel pressure regulator (914) from there it goes to the carbs …I’m no sure about this report IMO
I find it’s strange that water was then only in one carb bowl? And if the set of pots being fed from the non contaminated carb were producing full power they would have pulled it through ( kept the engine going) till it cleared …

 

[Abid]

Both are fed from a fuel pressure regulator (914) from there it goes to the carbs …I’m no sure about this report IMO
I find it’s strange that water was then only in one carb bowl? And if the set of pots being fed from the non contaminated carb were producing full power they would have pulled it through ( kept the engine going) till it cleared …

Exactly what I thought also. Is it possible though that with enough water in one carb and a smaller amount of water in the other, one side ran very rough but didn't quit but the other completely quit and that could have shut down the whole engine? This way in one bowl the water got injested and used up but the other completely it remained to be found later as it had literally quit.
What also does not make sense is if Tony was trying to make that road, why would he go from max glide speed to 76 knots. That would kill his glide. Maybe the engine was still running but running rough or hesitently so he tried to speed up to get closer?

 

[Brent Smith]

Exactly what I thought also. Is it possible though that with enough water in one carb and a smaller amount of water in the other, one side ran very rough but didn't quit but the other completely quit and that could have shut down the whole engine? This way in one bowl the water got injested and used up but the other completely it remained to be found later as it had literally quit.
What also does not make sense is if Tony was trying to make that road, why would he go from max glide speed to 76 knots. That would kill his glide. Maybe the engine was still running but running rough or hesitently so he tried to speed up to get closer?

Is it possible there's a simpler answer for why there was water in only one float bowl? Might it have resulted from spraying the engine with water while washing the aircraft, hitting the carb just 'right' on one side but not the other?

 

[Abid]

Is it possible there's a simpler answer for why there was water in only one float bowl? Might it have resulted from spraying the engine with water while washing the aircraft, hitting the carb just 'right' on one side but not the other?

Unlikely. The carbs are sealed in 914 and are pressurized and usually are 4 to 5 psi of pressure for the Turbo

 

[Vance]

This report is a very sobering reminder of every detail we need to pay attention to in aircraft. Tony Mattioli had a fatal accident in an AR-1 gyroplane (N11TG) here in Florida in 2021. Tony was a super guy and very good and capable airplane IFR and gyroplane Sport Pilot. He loved flying his AR-1 powered with a Rotax 914.
The NTSB final report points out that in the end he went down because his Rotax 914 engine quit because of water contamination in the right carb bowl. That is definitely what happened though somethings do not make sense still but certainly the engine was not running when he hit the trees and then the ground. The engine ran fine on the gas in the tank once the carb bowl was cleaned up. There was no water found in the fuel tank.
I am at a loss on how after 1.5 hours there was water in only one carb bowl when the fuel from the tank comes in one way and gets tee'd to each carb and why water would come in after 1.5 hours of flight and not right at the beginning of the flight as water should settle to the bottom where fuel pick up and fuel sample quick drain is. I know ethanol can keep water dissolved/mixed in the fuel but why would it separate 1.5 hours later???

Do you know if he was running automobile fuel with alcohol or 100LL from the airport Abid?

If it was 100 LL I would expect the water to separate out.

I have had very little experience with a 914 in an American Ranger.

In two different 914 powered Cavalons flying around Santa Maria at low power settings on a less than sixty degrees F day with humidity over eighty percent I have had what I suspect was carburetor ice.

Mostly it would just run rough on approach.

The only time it stopped altogether was practicing engine at idle landings.

It would not start until it had sat for a while and then it would start and run rough for a bit and then run fine.

I did not inspect the float bowls every time and when I did there was corrosion in the right float bowl on both aircraft and nothing I could recognize as water.

Neither was equipped with carburetor heat and I cannot be certain it was carburetor ice.

In a Cavalon the turbocharger is below the carburetor on the left side of the aircraft and after performing stop and goes for .8 hours the carburetor on the left side would be hot to the touch and the carburetor on the right side of the aircraft would have condensation on it.

I have experienced vapor lock on hot days in a 914 powered Cavalon burning automobile gas and this was very different and always on a cool summer day and burning 100LL.

 

[Abid]

Do you know if he was running automobile fuel with alcohol or 100LL from the airport Abid?

If it was 100 LL I would expect the water to separate out.

I have had very little experience with a 914 in an American Ranger.

In two different 914 powered Cavalons flying around Santa Maria at low power settings on a less than sixty degrees F day with humidity over eighty percent I have had what I suspect was carburetor ice.

Mostly it would just run rough on approach.

The only time it stopped altogether was practicing engine at idle landings.

It would not start until it had sat for a while and then it would start and run rough for a bit and then run fine.

I did not inspect the float bowls every time and when I did there was corrosion in the right float bowl on both aircraft and nothing I could recognize as water.

Neither was equipped with carburetor heat and I cannot be certain it was carburetor ice.

In a Cavalon the turbocharger is below the carburetor on the left side of the aircraft and after performing stop and goes for .8 hours the carburetor on the left side would be hot to the touch and the carburetor on the right side of the aircraft would have condensation on it.

I have experienced vapor lock on hot days in a 914 powered Cavalon burning automobile gas and this was very different and always on a cool summer day and burning 100LL.

If I remember right he had told me that he used gas from a local gas station in Deland. Maybe a seven eleven gas station or something. He also owned a Tecnam and used the same gas in it.

I think I have experienced what you did in the Cavalon in another 914. I suspect that is vapor lock not carb ice. Cavalon engine cowling did not facilitate cooling specially if you went to low power setting for a while.

The fact that you had a hot carb and a cooler one is interesting though.

 

[Vance]

For me the takeaway from this accident is when flying over terrain with limited landing options; fly higher or change my route and fly best glide speed when the engine goes quiet.

I regularly practice simulated engine outs and have found I cannot stretch the glide.

When things become challenging I don’t always make the best decisions.

In my opinion based on my experience; there is a lot of luck involved in an engine out landing in a gyroplane without damage to the aircraft or the pilot.

 

[Greg Vos]

Do you know if he was running automobile fuel with alcohol or 100LL from the airport Abid?

If it was 100 LL I would expect the water to separate out.

I have had very little experience with a 914 in an American Ranger.

In two different 914 powered Cavalons flying around Santa Maria at low power settings on a less than sixty degrees F day with humidity over eighty percent I have had what I suspect was carburetor ice.

Mostly it would just run rough on approach.

The only time it stopped altogether was practicing engine at idle landings.

It would not start until it had sat for a while and then it would start and run rough for a bit and then run fine.

I did not inspect the float bowls every time and when I did there was corrosion in the right float bowl on both aircraft and nothing I could recognize as water.

Neither was equipped with carburetor heat and I cannot be certain it was carburetor ice.

In a Cavalon the turbocharger is below the carburetor on the left side of the aircraft and after performing stop and goes for .8 hours the carburetor on the left side would be hot to the touch and the carburetor on the right side of the aircraft would have condensation on it.

I have experienced vapor lock on hot days in a 914 powered Cavalon burning automobile gas and this was very different and always on a cool summer day and burning 100LL.

As far as I understand …and with respect what do I know….you cannot get carb icing with a turbo ..if you can I better get to ground school, ?Rotax 9 series are notoriously known for very rough running between 2000 and 3000 rpm ,all to do with fuel air ratio

 

[Abid]

For me the takeaway from this accident is when flying over terrain with limited landing options; fly higher or change my route and fly best glide speed when the engine goes quiet.

I regularly practice simulated engine outs and have found I cannot stretch the glide.

When things become challenging I don’t always make the best decisions.

In my opinion based on my experience; there is a lot of luck involved in an engine out landing in a gyroplane without damage to the aircraft or the pilot.

True. As we see it was not the engine, it was fuel contamination here that caused the issue. So even with reliable aircraft engines you can have issues where in a car we can pull over but in an aircraft it is a different story. Still you cannot always have a perfect landing spot all the time in glide distance. There is always a risk that we accept as pilots. Getting good fresh fuel is crucial.

 

[WaspAir]

As far as I understand …and with respect what do I know….you cannot get carb icing with a turbo ..if you can I better get to ground school,

If you have significant boost going on, it often keeps the carb hot enough that the risk is truly minimal. However, if your wastegate operates such that you're not getting meaningful boost in your current flight condition, it is still possible to get ice. That's why I have carb heat, and air filter & carb temp guages, in my turbocharged Bell (Lycoming TVO 435). I am essentially never in the yellow zones at my current high field elevation because the boost up here is always enough to warm it up nicely.

The worst ice I ever faced was while warming up a normally aspirated R22 Alpha at sea level in New Jersey on a cool very humid day (on the ground, fortunately).