Emergency landing

[CTMI]

Wife and I were flying along at

5250RPM

60 psi oil pressure

218 oil temp

1360-1390 EGT

fuel flow 5.2 gph @ 4.3 PSI

Right cylinders were 10-15 degrees hotter than left, and the EGT on the right was about 120 degrees hotter than the left. 

 

Then in half a second, the rpm dropped to 4500 rpm and the engine was bogging. We were right near an airport and landed immediately. 

On the ground, immediately after landing i had one side mag drop of 100 and the other side dropped around 200 I think* a lot of adrenaline)

i am certain though that when I went full throttle on the ground after landing the engine only went to 4000-4300 and was audibly "bogging" and running really rough.

Then the plane sat for 30-45 minutes while I arranged a hangar for it.

When I started it 30-45 minutes later, it everything has cooled substantially, and the engine ran PERFECT. 90-100 rpm mag drop, and the engine went right up to 4800 rpm and ran smooth as glass. 

I left the plane at that airport and have a mechanic who will drive to it. 

Does anyone have any idea what went wrong? 

I am thinking it was ignition related because of how suddenly the rpm dropped. Also I have the "barrel" type key ignition and it's fairly loose/shotty, I can actually remove the key from it when it's in the ON position. Maybe it's the key??? 

Then again the more I read the more I think it was maybe carb debris?????

I could really use some help.

on a more humorous note, the adrenaline filled landing was probably my best ever. Go figure. 

 

 

[Runtoeat]

I just got done helping trouble shoot a CTLS with similar problems.  There was an emergency landing as a result of the engine not producing full power after takeoff. The ignition switch was the main cause for low rpm.  Because it was worn out and loose, it was rotating by itself to the "start" position.  This was putting the ignition modules in the soft start mode which caused the rpm to drop.  As you know, there are also many accounts of engines intermittently loosing power due to foreign material in the carburetor so this can't be ruled out and might be indicated by  the right side running hotter caused by leaner mixture from the right side carb.  Roughness might be due to this carb imbalance? Although I am not totally sure, I think it might be normal to be able to remove the key from the ignition when it is the "run" position.

[Tip]

Hi Dick, 

How many hours did the LS have on it?

[WmInce]

Good job, Dick.

Interesting.

[FlyingMonkey]

Oil temp 118?  Is that a typo?

[CTMI]

Haha yes sorry I meant 218 

[CT4ME]

'Could be a little something in the carb, partially blocking jet.  There have been many instances described here, especially after hose changes or engine work.... usually found in the bowl and described as "just a tiny fleck"...

[Roger Lee]

Sounds just like carb debris symptoms. Here's all you have to do and be back in the air in 30 minutes.

 

 

[CTMI]

Yep. Gunk in the bowl. Got it out and gained 300 rpm at WOT and it runs drastically smoother. Fixed! 

Thanks Roger! 

This forum is the BEST! 

[Ed Cesnalis]

Were your fuel lines replaced?  There might be more to come.

[Runtoeat]

This appears to be a textbook problem involving carb debris.  Wish they were all this cut and dried.  Glad you're back in the air.

Tip, the CTLS had a ignition switch problem with low 200 hours on it when the problem first occurred last year.  Cleaning the switch seemed to correct the problem.  John is a Forum member and can correct me if the hours aren't correct.  The plane again had a problem this year which occurred after takeoff and a quick 180 turn was needed to get back to the runway under low engine power.  John's mechanic installed a new ignition switch and a shielded power wire to the soft start pins on the modules.  This corrected the problem.