Cylinder 1 very low temp and running rough- Piper Arrow

Jake Simpson

Jake Simpson

Filing Flight Plan
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As I was flying my 1969 Arrow I today, I was doing some light maneuvering at 6000' normal cruise power setting. Upon feeling a slight shake begin coming from the engine, I looked at my CHTs and noticed cylinder 1 was far lower than the other three, which were running normally. The engine ran fine with a noticeable roughness so I landed immediately. Would this be an issue with the ignition system? (Spark plugs/mags) Or maybe even a bad fuel injector for Cyl 1? It seems that that cylinder was just not making power. I have the normally aspirated IO360 200hp
 
Clip4 said:
I vote injector.
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You may be right, but easiest to check air, then spark, before fuel. Air & spark can be checked easily by owner, fuel not so much. Eliminate those two first, then take it in for service.
 
Engines need compression, fuel and spark to run. So we need to look at what, of those things, can happen to just one cylinder.

Compression:
Possible issue with the jug itself.

Fuel:
Injector - possible.
Intake leak - possible, but generally runs hotter, so less likely to me.

Spark:
Ignition wire - possible.
Spark Plug - possible.
But each of these would only cause 1 of 2 plugs to fail, so less likely to me.


Is this thought-train helpful?
 
Have you had any maintenance done very recently?
Was your pre-takeoff mag check normal?
Do you have an engine monitor?
Did you do a mag check after landing?
 
Well guys, the culprit has been found. Exhaust pipe from Cyl 1 completely detached, explains the low EGT (Yes it was EGT, not CHT my bad) and shaking. I checked all the other cylinder pipes and while the left side (cyl 2/4) look fine, cylinder 3 is cracked at the flange. That is definitely going to need to be fixed too. What do y'all recommend, taking it to a weld shop? Or should I just replace the pipes or whole exhaust itself?
 

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Not repairable IMO. Number 3 had already cracked and a repair was attempted at some point.
 
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It's under strain and will likely try and crack again even after welding the crack. We added additional gussets which has worked for hundreds of hours but we've had to revisit the repair.
 
Jake Simpson said:
What do y'all recommend, taking it to a weld shop? Or should I just replace the pipes or whole exhaust itself?
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Talk to an exhaust shop like Dawley, Acorn, AWI, or WagAero and get your options. At the shop level a repair usually involves replacing the entire tube vs simply welding the crack. Have used this route the most when dealing with similar problems.
 
Many exhaust issues are due to “Slip Joints “ that don’t slip.
 
Magman said:
Many exhaust issues are due to “Slip Joints “ that don’t slip.
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If a Power flow system is available for your plane I would consider it.
I have one on a 172 that works well. I do take it off a couple time per year to reapply anti seize to the slip joints. Pretty easy deal on my 172.
AJOR3018.JPG
 
FORANE said:
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It's under strain and will likely try and crack again even after welding the crack. We added additional gussets which has worked for hundreds of hours but we've had to revisit the repair.
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I would definitely get the advice of a good mechanic, but this seems like very good advice to me from this previous post. My experience with airplane maintenance is that when you try to shortcut and save a dollar, you usually have to revisit the problem and wind up spending more money and aggravation in the long run. I just recently put a new exhaust system on my Cherokee because I don’t want to have to deal with this again in the future.

Best of luck with your repair.
 
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Yikes that looks expensive. Sorry. But good you caught it.
 
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