Doing the first annual now... wowza!!

[Mr Bill]

1968 M20G, airworthiness date on FAA site 7/29/68.  Retractable step, fixed cowl flaps, "drooped" wing outer sections.

Bill

[Hank]

Having only flown one other plane (a piper warrior, which is much less prone to carb ice), I'm still struck by how dramatic the rpm drop is in the M20C with carb heat on at run up.   I assume we have a more effective heating system given our carb's high propensity to make ice?  It still makes me a little uneasy when I turn it on for descent/landing, lest the rich mixture fouls the plugs, or I forget to turn off for a go-around.  My MSC prebuy mechanic suggested only pulling it on half way, but I think I'll wait until I have a carb temp gauge until I try this.

Carburetor Temp gauges are great.

I never add it for descent, because I don't reduce power. I do walk throttle and mixture to keep cruise MP & EGT until slowing for pattern entry.

[treebobboy]

Bluehighwayflyer,   N6832N,  certificate issued 4/17/68, SN 680111, dorsal fin--yes, fixed cowl flaps, single piece front windshield, flush screws on the windshield, protruding screws on all other windows.

[HRM]

1968 M20G....Retractable step.....

Bill

 

Is that automatic (vacuum) or pilot-powered?

[DXB]

Thanks for the information.  Obviously, then, these changes were phased in over time.  There used to be a '68 C model in our community hangar back in the 80s that was equipped just like your '68 G model except that it had a fixed step.  We had a '65 C in the same hangar so comparisons were easy.  Obviously MAC phased these changes in over time.  But '68 was a key pivotal year.  Is there anyone here with a '69 model or later with a retractable step? 

 

Good stuff.  Thank you again for correction.

 

Jim

My '68C is serial #2 for the year, with an airworthiness certificate in Nov '67- it has the fixed step, so I guess there is disparity among the models that year.

[gsxrpilot]

Having only flown one other plane (a piper warrior, which is much less prone to carb ice), I'm still struck by how dramatic the rpm drop is in the M20C with carb heat on at run up.   I assume we have a more effective heating system given our carb's high propensity to make ice?  It still makes me a little uneasy when I turn it on for descent/landing, lest the rich mixture fouls the plugs, or I forget to turn off for a go-around.  My MSC prebuy mechanic suggested only pulling it on half way, but I think I'll wait until I have a carb temp gauge until I try this.   

I just crossed 125 hours in my C and have never experienced carb ice. I've got an inlet temp gauge but have just about quit looking at it. I check that the carb heat works during each run-up. I don't ever think about carb ice when making a descent. Sometimes I leave the power in and come down with trim, pushing the VNE line, other times I cut the power and come down at idle power. It's only been 125 hours, but I've never had ice in the carb.

[Andy95W]

I just crossed 125 hours in my C and have never experienced carb ice. I've got an inlet temp gauge but have just about quit looking at it. I check that the carb heat works during each run-up. I don't ever think about carb ice when making a descent. Sometimes I leave the power in and come down with trim, pushing the VNE line, other times I cut the power and come down at idle power. It's only been 125 hours, but I've never had ice in the carb.

Agreed. Lycomings in general tend not to pick up carburetor ice because the carburetor is bolted to the hot oil sump.

The only time I definitely picked up carb ice was at 10,000 feet in and out of the tops of clouds. OAT just above freezing, so no wing ice, just carburetor.

[Hank]

I just crossed 125 hours in my C and have never experienced carb ice. I've got an inlet temp gauge but have just about quit looking at it. I check that the carb heat works during each run-up. I don't ever think about carb ice when making a descent. Sometimes I leave the power in and come down with trim, pushing the VNE line, other times I cut the power and come down at idle power. It's only been 125 hours, but I've never had ice in the carb.

Yep, I'm right at 600 hours in my C (wow! Already?), and have never had any carb ice. Flew 6-1/2 winters in WV / KY / OH and never had any ice of any kind. Flew through some light snow a few times, and over an awful lot of white ground. Even living in the Ohio River Valley, no carb ice issues, only use carb heat right after engine start (not during runup) and when entering clouds with Carb Temp in the orange stripe.

Im not sure how much of that is due to prudent ADM, how much to good design, and how much due to always making power-on descents.

[DXB]

Huh- interesting. This reduces my pucker factor a bit.

My '68C is serial #2 for the year, with an airworthiness certificate in Nov '67- it has the fixed step, so I guess there is disparity among the models that year.

  

I just crossed 125 hours in my C and have never experienced carb ice. I've got an inlet temp gauge but have just about quit looking at it. I check that the carb heat works during each run-up. I don't ever think about carb ice when making a descent. Sometimes I leave the power in and come down with trim, pushing the VNE line, other times I cut the power and come down at idle power. It's only been 125 hours, but I've never had ice in the carb.

  

Agreed. Lycomings in general tend not to pick up carburetor ice because the carburetor is bolted to the hot oil sump.

The only time I definitely picked up carb ice was at 10,000 feet in and out of the tops of clouds. OAT just above freezing, so no wing ice, just carburetor.

  

Yep, I'm right at 600 hours in my C (wow! Already?), and have never had any carb ice. Flew 6-1/2 winters in WV / KY / OH and never had any ice of any kind. Flew through some light snow a few times, and over an awful lot of white ground. Even living in the Ohio River Valley, no carb ice issues, only use carb heat right after engine start (not during runup) and when entering clouds with Carb Temp in the orange stripe.

Im not sure how much of that is due to prudent ADM, how much to good design, and how much due to always making power-on descents.

[drapo]

Yep, I'm right at 600 hours in my C (wow! Already?), and have never had any carb ice. Flew 6-1/2 winters in WV / KY / OH and never had any ice of any kind. Flew through some light snow a few times, and over an awful lot of white ground. Even living in the Ohio River Valley, no carb ice issues, only use carb heat right after engine start (not during runup) and when entering clouds with Carb Temp in the orange stripe.

Im not sure how much of that is due to prudent ADM, how much to good design, and how much due to always making power-on descents.

 

Don't make the mistake of mixing ice, or colder temperatures, and carburetor ice!

 

You can get carb ice at temperatures in the 50's or 60's on a beautiful summer day...

 

Here's a chart to freshen up your carb icing skills.

 

[DaV8or]

1968 M20G, airworthiness date on FAA site 7/29/68.  Retractable step, fixed cowl flaps, "drooped" wing outer sections.

Bill

 

Interesting. I have always been told that only the 66-67 Fs had twisted wings and that in '68 they went back to the straight wing. I guess the Gs did too. Do you have a low serial number?

[Hank]

Drapo--

 

I can't quote you above, but I'm aware that carb ice and airframe icing are different; just wanted to say that I've not experienced either despite living in the humid river valley, with the airport literally on the riverbank. Carb ice is definitely humidity related, and happens much more often in summer than in winter. We had one incident involving carb ice at the field that I know of, losing the plane I trained in diving for the field, getting too fast to land, and stalling into the trees off the end of the runway. Minor cuts, a broken arm and a totaled Skyhawk . . . the pilot is flying again, but I don't think his wife will ever ride with him again.

 

Whoever added the "optional Carb Temp gage" to my plane did all subsequent owners a tremendous favor! It's really nice to know when to worry and when not to. On those occasions, just move the little lever until the needle is out of the striped caution area. I've done so maybe a half-dozen times, the most recent immediately below the cloud layer [limited horizon, dragging the tail through the clouds] with OAT at 31º over Greenville, SC and the carb temp gage was well into the orange stripe. Temps fell quickly that night as I headed north. A little carb heat and some pitot heat, vector away from GSP and request for lower cured all.

 

Fly safe out there, ya'll!

[drapo]

Hank,

Sorry, might have misread your post, but just wanted to make sure. We had a guy up here who stopped flying his Cessna for two years and spent all kind of money having his ignition and fuel system checked after he experienced a loss of power at altitude on a beautiful summer day.

When people told him he had a carb icing experience, he just didn't believe them, because he said he added carb heat and nothing happened. Ended up his carb heat wasn't working properly...

[Mooneymite]

I'm not sure why people are so resistant to using Carb heat. For those of us without a Carb temp gauge, the POH is pretty specific about using it.

It costs nothing! Re-lean the mixture and keep on flying. Un-filtered air is no big deal except for ground ops and dusty conditions.

The NTSB keeps track of the number of accidents attributed to carburetor icing and probable Carb icing. It happens with surprising regularity, but the prevention is free. Totally free!

Yes, you can add a Carb temp probe....or just use the Carb heat when called for by the POH. I would feel better about a Carb temp probe if it illuminated a warning light, but constantly keeping an eye on it is beyond my brain's attention span.

I operate off of turf, so I generally turn off Carb heat with my final gear check on short final. This prevents dust ingestion after landing and sets me up for a full power go-around if needed. It is my personal technique; I do not recommend it for others, but just suggest it as an option.

[Andy95W]

Don't make the mistake of mixing ice, or colder temperatures, and carburetor ice!

You can get carb ice at temperatures in the 50's or 60's on a beautiful summer day...

Here's a chart to freshen up your carb icing skills.

But the chart still doesn't take into account the difference between our Lycoming engines (carb bolted to the hot oil sump) and the Continental (carb dangling out in the cold air).

I'm not sure why people are so resistant to using Carb heat. For those of us without a Carb temp gauge, the POH is pretty specific about using it.

It costs nothing! Re-lean the mixture and keep on flying. Un-filtered air is no big deal except for ground ops and dusty conditions.

The NTSB keeps track of the number of accidents attributed to carburetor icing and probable Carb icing. It happens with surprising regularity, but the prevention is free. Totally free!

Yes, you can add a Carb temp probe....or just use the Carb heat when called for by the POH. I would feel better about a Carb temp probe if it illuminated a warning light, but constantly keeping an eye on it is beyond my brain's attention span.

I operate off of turf, so I generally turn off Carb heat with my final gear check on short final. This prevents dust ingestion after landing and sets me up for a full power go-around if needed. It is my personal technique; I do not recommend it for others, but just suggest it as an option.

+1. Describes exactly how I fly. And I always use flaps for take-off.

[DXB]

I'm not sure why people are so resistant to using Carb heat. For those of us without a Carb temp gauge, the POH is pretty specific about using it.

It costs nothing! Re-lean the mixture and keep on flying. Un-filtered air is no big deal except for ground ops and dusty conditions.

The NTSB keeps track of the number of accidents attributed to carburetor icing and probable Carb icing. It happens with surprising regularity, but the prevention is free. Totally free!

Yes, you can add a Carb temp probe....or just use the Carb heat when called for by the POH. I would feel better about a Carb temp probe if it illuminated a warning light, but constantly keeping an eye on it is beyond my brain's attention span.

I operate off of turf, so I generally turn off Carb heat with my final gear check on short final. This prevents dust ingestion after landing and sets me up for a full power go-around if needed. It is my personal technique; I do not recommend it for others, but just suggest it as an option.

Nice discussion to hear for a newbie, and interesting idea to turn carb heat off when rechecking GUMPS on short final, after having it full on during descent.  My first practice go arounds in a Mooney recently went fine with turning it off, but in a real world late decision to go around when something goes bad near touchdown, having to deal with only throttle and regaining control could make a big difference.  Probably a dumb question, but is there any risk of plug fouling from having carb heat on at descent power settings with rich mixture, or does that really only happen near idle (as I've already experienced during taxi x2)?   Continuously enriching mixture with decreasing altitude seems like too much to me, so I imagine folks generally run pretty rich during descent, which is exacerbated if you use carb heat?

[DXB]

But the chart still doesn't take into account the difference between our Lycoming engines (carb bolted to the hot oil sump) and the Continental (carb dangling out in the cold air).

+1. Describes exactly how I fly. And I always use flaps for take-off.

I also wonder if the cowl closure mods on the guppy mouth planes that so many including myself have can alter temps around the carb enough to influence ice risk in either direction.   Doubt it would be enough to alter the carb heat usage recs, but just curious.   

[Andy95W]

Probably a dumb question, but is there any risk of plug fouling from having carb heat on at descent power settings with rich mixture, or does that really only happen near idle (as I've already experienced during taxi x2)?   Continuously enriching mixture with decreasing altitude seems like too much to me, so I imagine folks generally run pretty rich during descent, which is exacerbated if you use carb heat?

I lean aggressively any time I am at low power settings, like in the descent or while taxiing. Below 60% power you won't hurt anything. There are some discussions about the "Red Box" and leaning by Mike Busch you would probably find interesting.

On final, I go to full rich and carb heat off, just in case of a go-around.

[Hank]

[quotdescendinge=DXB" post="198098" timestamp="1424367774]Nice discussion to hear for a newbie, and interesting idea to turn carb heat off when rechecking GUMPS on short final, after having it full on during descent.  My first practice go arounds in a Mooney recently went fine with turning it off, but in a real world late decision to go around when something goes bad near touchdown, having to deal with only throttle and regaining control could make a big difference.  Probably a dumb question, but is there any risk of plug fouling from having carb heat on at descent power settings with rich mixture, or does that really only happen near idle (as I've already experienced during taxi x2)?   Continuously enriching mixture with decreasing altitude seems like too much to me, so I imagine folks generally run pretty rich during descent, which is exacerbated if you use carb heat?

[DXB]

I lean aggressively any time I am at low power settings, like in the descent or while taxiing. Below 60% power you won't hurt anything. There are some discussions about the "Red Box" and leaning by Mike Busch you would probably find interesting.

On final, I go to full rich and carb heat off, just in case of a go-around.

Thanks the Mike Busch discussion of red box/red fin was indeed illuminating- very lean at <60% power indeed seems minimal risk.     Brings some ROP/LOP questions to mind but I'll spare everyone and do some more reading.

[ryoder]

Great point about carb heat off on final. I might start doing that too once the runway is made.