Approach to landing mistake - lesson learned!

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Late this afternoon while on a visual approach to my home airport the plane started to vibrate very unusually. I was descending out of approximately 2000ft, just 2 - 3 minutes from touchdown. As I descended the vibration got worse and I became confused, first thinking that maybe I hit something, that something on the plane came loose, or that something was wrong with the prop / the prop fell out of balance. Then I glanced at the engine monitoring gauge and saw EGTs for a few cylinders dropping off the gauge, and thought "I can't believe I am about to loose my engine right before landing!".

After what seemed like a lifetime of panic, (probably about 10 - 12 seconds from the start of the event to finish), and reacting to the dropping EGTs I pushed the throttle forward, and the engine roared with power, but still with some vibrations. My next check turned out to be the culprit....the mixture was still leaned out!

I was so focused on dealing with the high winds on landing that I completely forgot to do a GUMPS check, and left the mixture way too lean. This starved the engine of fuel at low throttle and RPM, and a few cylinders must have stopped firing, causing the vibration.

Very scary, and I feel like a total idiot. I NEVER forget to do GUMPS, but got so busy focused on the winds I failed to do the landing checklist.

Now I know what it feels like to be in serious distress. It was a very sobering lesson learned, and I'll never miss a landing checklist ever again!
 
Glad it worked out for ya and ended up being a good learning opportunity. I, of course, have never done that, but I've got, um, a buddy :wink2: that's done that a few times... Lets just say that I'm glad I don't have a mixture to worry about anymore...
 
What plane were you in?

A change in behavior due to experience, you have learned and probably won't ever forget again.

Don't let it get to you. And thanks for sharing your experience.

Remind me to tell you how I paniced and declared an emergency because I let the right seat belt get out the door on my first night solo.....
 
Unless you advanced the throttle above the cruise power setting to which the mixture had been leaned, you should not have seen any cylinders drop off like that just because the mixture was still leaned to the cruise setting. In fact, in a normally aspirated engine (especially a carbureted model), the mixture gets richer, not leaner, as you reduce power. Lycoming even says that during a low-power descent, you may have to lean the engine further in order to maintain optimum fuel-air mixture. Further, you'd have to be awfully lean (well below the normal cruise power mixture position) to have a couple of cylinders quit completely. So, if this happened at a reduced power setting, I'd be checking the ignition system, not blaming it on cruise-leaned mixture.
 
IO-540, 260 hp. If I descend 500 fpm from 12,500'+ at my normal 30-40F LOP mixture setting, pull rpm from 2400 back to 2100, pull throttle as needed to maintain my cruise MP and don't touch the mixture...I will get a 1500F EGT warning due to running very lean around 2-3,000'. If I don't richen slightly, the flame will go out soon after during approach. Of course it does not get rough unless you advance the throttle a little.

At cruise altitudes lower than that, running same LOP setting it has not been an issue.
 
Good job ,always good when you can learn,without doing damage to yourself,or the airplane.
 
I was with another pilot a few months ago (I swear - I wasn't flying) at 8000'. He had aggressively leaned the 182T to about 9 GPH at I think ~110 KIAS. Over Lake Erie we were given a descent, so he pulled the power, set up for 500FPM, and waited. The obvious happened. With no descent checklist run, the airspeed got lower and lower and the autopilot pitched higher and higher. At about 72 knots indicated, I look at the pilot and said "er, something's wrong.." and pushed the mixture back in. (not so) Incredibly, we started flying again.

We humans are too distractible. I am sure we all have forgotten our GUMPS many times!
 
ChrisK said:
I was with another pilot a few months ago (I swear - I wasn't flying) at 8000'. He had aggressively leaned the 182T to about 9 GPH at I think ~110 KIAS. Over Lake Erie we were given a descent, so he pulled the power, set up for 500FPM, and waited. The obvious happened. With no descent checklist run, the airspeed got lower and lower and the autopilot pitched higher and higher. At about 72 knots indicated, I look at the pilot and said "er, something's wrong.." and pushed the mixture back in. (not so) Incredibly, we started flying again.

We humans are too distractible. I am sure we all have forgotten our GUMPS many times!
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And if you touch my red knob again - I kill you :D
 
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Ron Levy said:
Unless you advanced the throttle above the cruise power setting to which the mixture had been leaned, you should not have seen any cylinders drop off like that just because the mixture was still leaned to the cruise setting. In fact, in a normally aspirated engine (especially a carbureted model), the mixture gets richer, not leaner, as you reduce power. Lycoming even says that during a low-power descent, you may have to lean the engine further in order to maintain optimum fuel-air mixture. Further, you'd have to be awfully lean (well below the normal cruise power mixture position) to have a couple of cylinders quit completely. So, if this happened at a reduced power setting, I'd be checking the ignition system, not blaming it on cruise-leaned mixture.
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Do you have a pointer to Lycoming doc that talks about this?
 
ChrisK said:
I was with another pilot a few months ago (I swear - I wasn't flying) at 8000'. He had aggressively leaned the 182T to about 9 GPH at I think ~110 KIAS. Over Lake Erie we were given a descent, so he pulled the power, set up for 500FPM, and waited. The obvious happened. With no descent checklist run, the airspeed got lower and lower and the autopilot pitched higher and higher. At about 72 knots indicated, I look at the pilot and said "er, something's wrong.." and pushed the mixture back in. (not so) Incredibly, we started flying again.

We humans are too distractible. I am sure we all have forgotten our GUMPS many times!
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Yeah I've done that.
 
 
Try to work your engine analyzer into your normal scan.

Not sure if it is true here, one of the things that always baffled me, folks install all this fancy stuff in their panel, spend all this money, get a nice analyzer but they'll mount the JPI way on the right side :mad2:

Mine is set up like that right now, I even have a spacer right under my second nav head where it would fit like a glove, that'll be part of my winter polishing and tweaking the plane project.
 
James331 said:
Not sure if it is true here, one of the things that always baffled me, folks install all this fancy stuff in their panel, spend all this money, get a nice analyzer but they'll mount the JPI way on the right side :mad2:
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You mean like the G1000? Not only is the engine analyzer on the right screen, you can only see it when you push two soft keys. It's clearly intended only for leaning.
 
MAKG1 said:
You mean like the G1000? Not only is the engine analyzer on the right screen, you can only see it when you push two soft keys. It's clearly intended only for leaning.
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Which is why I keep it up most of the time ;)
 
MAKG1 said:
But then, you lose the volt/ammeters, oil pressure/temperature, EGT and vacuum.
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Actually, you have EGT in that view as wel as the standard fault indicators on the PFD, and I did not say I pull it up and break the knobs off and stare at it to the exclusion of all other instruments. I favor seeing the CHT numbers much of the time. That's all.
 
 
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