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80kt headwinds and early Mooneys


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80 knot headwind?

On April 14th I was sitting on the ground at Dickson TN as a cold front moved through, bringing thunderstorm cells and lightning and some serious downpours with it. I knew if I waited a few hours, it would be gone and the only thing between me and my home base of KTRL near Dallas would be light rain, IMC, and very strong headwinds.
The forecast was for 40 knot headwinds. I was not looking forward to my 2.5 hour flight turning into 3 hours, but I was willing to accept it as a necessary evil.
I filed my IFR flight plan, got my clearance, and took off into the clouds, climbing to my cruising altitude of 8000 feet in mist and light rain. The ground was sort of visible below, but water streaked the windscreen.

(I should mention here that I can hear you saying "you dork, why not fly at 4000 feet and take a 20 kt reduction in headwind?" My answer is that my M20A doesn't like to fly that low. It produces > 200 degree differences in EGT between cylinders because of the lousy job Lycoming did designing the intakes, and that sets off my EI engine monitor alarm. I never fly that low.)

So upon reaching cruising altitude, trimming everything up, and leaning, I settled in for my 3 hour leg to KSUZ outside of Little Rock. And I started watching my ground speed to see if the 40kt predictions were correct.
But instead of seeing something like 105 kts of groundspeed, I was seeing 90, then 80 knots. Then 70 knots. My GPS was telling me it would be 3 and a half hours flying time. I was getting more and more amazed at the hellacious headwinds.

Then my Bitchin' Betty voice annunciator interrupted me as she spoke into my headset "Check Engine Analyzer". I quickly glanced at the engine analyzer and noticed that the #3 cylinder was running over 200 degrees richer than the rest. I tweaked the mixture control, but it didn't make much difference. "Check Engine Analyzer" she said again.
At this point I looked at the manifold pressure gauge. Wow, 15 inches. The airspeed indicator said 115mph. Ground speed was down to 65mph. Hey wait a minute, I should be seeing a lot higher indicated airspeed and MP at 8000 feet. I quickly concluded there was something wrong with cylinder #3 and that was robbing my engine of power.

This was not an 80 knot headwind. This was an engine problem!

Many of us learned to fly in a Cessna 152. I still remember how the approach to landing power reduction was drilled into my head by my CFI, Bill Riggins, in 1983:
Abeam the numbers, pull carb heat, reduce throttle to 1500 RPM, hold altitude until the airspeed drops inside the white arc, then lower one notch of flaps. Yada yada.
When I started transition training in my M20A, my instructors told me I will rarely ever need carb heat during approach to landing. And indeed, in 12 years of flying, I have never needed carb heat.
But I remembered someone saying, if you're having difficulty in a carbureted Mooney getting the cylinders to have a more balanced mixture, try adding carb heat.

So I did. And I watched the manifold pressure climb. 16, 17, 18, 19, 20. And the airspeed climbed. And the groundspeed climbed. And the #3 cylinder EGT rose.

I looked at the outside air temperature gauge. 56 degrees. Couldn't be carb ice. Could it? I turned off the carb heat and watched the engine power slowly begin to drop. 19", 18", 17". OK, carb heat it is. I flew with carb heat on until I popped out of the clouds. At that point, I tested carb heat and found it wasn't needed anymore, and I continued my flight as usual.

Greg Ellis reminded me of the graph showing severe carb icing possible from 25 degrees to 60 degrees with humidity levels around 75-100%. I was in probably 100% humidity at 56 degrees OAT, so very much in the danger zone. I'm not used to needing carb heat at cruise power settings, but in IMC in that temperature range, it may be worth thinking about this a lot more frequently in flight.

A friend of mine crashed and burned in his Pietenpol in Florida because of carb ice. In Florida. It can happen anywhere if the conditions inside the venturi are suitable for ice formation. In this case it happened fairly slowly, but I suppose it could also be much more abrupt.

"Take heed of thine airspeed, lest the ground rise up and smite thee. And take heed of thine dewpoint, lest the carb ice up and smite thee!"

nyc02fa025_1.jpg?la=en

 

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Thanks for the report.

I'm an advocate of following the POH with respect to carb heat, but yours is a perfect example where carb ice happened even at higher power settings.

Anyone who says, "I've NEVER had carb ice in my Mooney", always needs to add the word, "YET".  It happens.

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Dave,

Nicely detailed write-up!

Please update your avatar with you plane model and your home area...

It will help others following your guidance...

I had my bout of carb ice in one April in my M20C at max gross weight.  Would loved to have had an engine monitor with a carb temp display...  (three friends going to SnF a decade ago...). High MP oscillating between full carb heat on and off... Stuck VFR low, under some clouds... trying to get to a better area with less clouds....

Best regards,

-a-

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after that long, loosing MP, and power, and speed,  and heat,,,

you are lucky,,  really lucky that your engine still had enough heat in it to heat your carb and melt that ice..

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Once upon a time I actually had 120 kt headwinds in my C model Mooney. A 27 kt ground speed isn't fun.
A UPS pilot flying the same route the same time had over 200 kt headwinds.


Wow, if I ever have 120 headwind I will make a 180 and see if I can break the ground speed record for a C. I would definitely not continue to my destination with that headwind


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17 hours ago, Dave N1960 said:

 

--- My answer is that my M20A doesn't like to fly that low. It produces > 200 degree differences in EGT between cylinders because of the lousy job Lycoming did designing the intakes, and that sets off my EI engine monitor alarm. I never fly that low.

 

nyc02fa025_1.jpg?la=en

 

Great post Dave.

Just the other day I mentioned your smooth wooden wing Mooney to some of my friends here.

 

When I went through PPT, carb icing was frequently mentioned and the graph was on the sheet we filled in with other pertinent data like W&B, Flight plane etc…

Nowadays I fly behind fuel injected engine and don’t have to warry about that.

 

I don’t quite understand your comment about EGT differences at lower altitudes; I’d like to hear mere. How I understand it, actual EGT’s are not important but the GAMI spread is. I don’t have experience with carbureted engine in a Mooney, though. How different is M20A from C?

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 @Dave N1960  Nice illustration of dangerous carb ice cropping up even in the relatively resistant carb configuration for the Mooney.  I also share @Igor_Us confusion regarding a higher EGT on one cylinder being indicative of a problem and a need to fly higher altitudes.  The absolute EGT values don't mean much per my understanding. If one cylinder runs leaner, it should manifest simultaneously as both high CHT and EGT initially when running an overall rich mixture. If that's what is happening when pulling back the throttle to cruise at lower altitudes, I suspect you have a big induction leak on that cylinder.  Per my modest understanding, the ability to leave throttle plate open at higher altitudes prevents negative pressure sucking in outside air to lean the mixture. 

Anyway it's really cool to see an A model still getting regular use. 

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  • 2 months later...

I'll address a few of the things you guys have asked about.

It is true that absolute EGT doesn't mean anything, but my engine monitor checks for the differential between CHTs and EGTs, and will warn me if the spread between any 2 cylinders' EGT is over 200 degrees. This happens all the time at lower altitudes. My M20A manual suggests flying at 9,000 to 13,000 ft as "the most efficient altitude range for fuel economy and speed", and indeed I rarely fly below 7,500 at all if I'm going anywhere more than an hour away, just because I like to lean the engine and reduce drag. At that altitude, the induction system seems to do a better job of fuel distribution between the cylinders, so I don't get bitched at by my engine monitor. I always fly full throttle, with the prop backed off to just around 2,500 RPM. At 8,500 MSL I can get a fuel flow of around 10-10.5gph at 143-145kts TAS.

I believe the M20A and the M20C are probably nearly indistinguishable in terms of Lycoming carbureted performance and icing possibilities. I'm about a couple knots faster than an M20C just because of the smooth wings, lack of rivets, and minor things like that. I have outrun a 201 in a balls-to-the-wall race around Lake Powell.

This is really a cautionary tale about flying in clouds with rain and 100% humidity with a carbureted engine. I believe the way the carb is mounted directly to the O-360 transfers enough heat to prevent carb icing in almost any other situation, including the many landings I've done in Florida with high humidity. But I spent a lot of time in the clouds, in the rain, and misinterpreted the signals the engine was sending me, because I had never seen that kind of insidiously slow power loss.

MPG is right, I was indeed super lucky to have noticed it before the carb iced up totally, the engine quit, and would have quit producing enough heat to the carb heat box to melt it quickly before I reached the ground. I always had the mantra in mind in the event of a sudden engine failure "Carb heat on, fuel pump on, switch tanks", but if this slow icing had gone to the point of engine stoppage, even that would not have saved me.

 

 

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On ‎4‎/‎23‎/‎2018 at 3:47 AM, Igor_U said:

Nowadays I fly behind fuel injected engine and don’t have to warry about that.

Not necessarily true.

I have had my fuel injection servo ice up and almost make the engine quit.

This was in my M20F with the ram air on. I later found a tiny little note that said to close the ram air in icing conditions. The fact was I wasn't getting any airframe ice, but the servo still iced up. It didn't affect the MP but the mixture kept getting leaner until the mixture knob was all the way in and it was too lean. I was right over Kingman AZ and told ATC that I needed to land there. They asked if I was having an emergency and I said "Yes I am". All turned out fine. When I got down to about 5000 the engine started running right again, but I was below MEA so I couldn't continue at that altitude, so we spent the night in Kingman.

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7 hours ago, N201MKTurbo said:

Not necessarily true.

I have had my fuel injection servo ice up and almost make the engine quit.

This was in my M20F with the ram air on. I later found a tiny little note that said to close the ram air in icing conditions. The fact was I wasn't getting any airframe ice, but the servo still iced up. It didn't affect the MP but the mixture kept getting leaner until the mixture knob was all the way in and it was too lean. I was right over Kingman AZ and told ATC that I needed to land there. They asked if I was having an emergency and I said "Yes I am". All turned out fine. When I got down to about 5000 the engine started running right again, but I was below MEA so I couldn't continue at that altitude, so we spent the night in Kingman.

Yours is not the first time I’ve heard of a Mooney icing up with the RAM air open.  I client of mine almost went swimming in Lake Erie.

Clarence

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  • 2 weeks later...
On ‎6‎/‎30‎/‎2018 at 1:00 PM, N201MKTurbo said:

Not necessarily true.

I have had my fuel injection servo ice up and almost make the engine quit.

This was in my M20F with the ram air on. I later found a tiny little note that said to close the ram air in icing conditions. The fact was I wasn't getting any airframe ice, but the servo still iced up. It didn't affect the MP but the mixture kept getting leaner until the mixture knob was all the way in and it was too lean. I was right over Kingman AZ and told ATC that I needed to land there. They asked if I was having an emergency and I said "Yes I am". All turned out fine. When I got down to about 5000 the engine started running right again, but I was below MEA so I couldn't continue at that altitude, so we spent the night in Kingman.

How can you have a carb ice if you don't have a carburetor?

;)

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Not to start the argument but discussion was about carb ice and I said I don't have to worry about it in my F Model. Your response was:

On ‎6‎/‎30‎/‎2018 at 1:00 PM, N201MKTurbo said:

Not necessarily true...

I believe my statement is 100% true. :D

 

I understand about possibilities of servo icing and engine stoppage, though. POH clearly warns about that. In cruse always have RAM open in clear air and try always closing it if penetrating lone cloud. I have yet to experience engine stumble due to that and I am sure it wasn't a good experience for you. Thank you.

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