172R Sputtering...Rich Mixture?

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ColeThePilot

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ColeThePilot
Hey guys/gals. Can I get some opinions on something? I primarily fly a 99 172R...the airplane I plan on taking my first passengers up over the next couple of weeks.

I've noticed there's a little sputter that comes from the engine at power settings in the 30-60 percent operating range. Never during high power settings. It's happened in the pattern, during descents, and low/slow flight like you'll see in my attached video.

When I was still a student pilot I told my instructor about this, and he believed it's just a symptom of the engine running excessively rich. What do you guys think?

It happens maybe once every 3 flights or so. I have tried leaning on the ground at 1200 RPM as per the amplified procedures. Still happens though. The best way I can describe it is as an unhappy shudder coming from under the cowling that rattles the seats a bit. I decided to take a GoPro with me to capture it.

Here you go...

http://youtu.be/GYzOILn4nn8

Pay really close attention to the way it sounds!
 
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Maybe, or perhaps the mag timing is a bit off. Could also be a valve problem. It will be different at higher RPM.

Is it difficult to start cold?

Squawk it when in doubt. Never self-censor safety.
 
Don't know what it is but one sure thing, I wouldn't be happy continuing flying with the issue until it was identified and fixed ! And I certainly would not be contemplating taking passengers up

A game of Russian Roulette....not if but when will the motor not recover from the hiccup and quit altogether !
 
I've never had issues starting it. I've raised many concerns about the aircraft at this particular flight school/FBO.

For example...I saw their Cutlass take off with one of it's mains trailing behind the airplane, with the nose wheel and other main retracted. Right away notified them. Nothing was done...and a week later, the airplane made an emergency landing due to a landing gear malfunction.

They seem to write off issues quickly...
 
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Well...okay. The other option is to drive 45 minutes north though across a tolled bridge to an unfamiliar airport.

Nobody else has experienced roughness like this?
 
ColeThePilot said:
Well...okay. The other option is to drive 45 minutes north though across a tolled bridge to an unfamiliar airport.

Nobody else has experienced roughness like this?
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I'm going to be a bit frank here.

If you want someone to tell you it's OK to fly, you shouldn't fly today. It's not wise to shop for safety opinions, especially from random strangers on the Internet.
 
Geez, I'm so new to this community I've somehow managed to make it sound like I was surrendering a go/no go decision to random strangers! Just wanted to get other, more experienced eyes on it. Sorry.
 
ColeThePilot said:
Geez, I'm so new to this community I've somehow managed to make it sound like I was surrendering a go/no go decision to random strangers! Just wanted to get other, more experienced eyes on it. Sorry.
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Hey don't worry about it Sir, I've seen many get flamed here for much less...:D
But fly safe buddy :thumbsup:
 
MAKG1 said:
I'm going to be a bit frank here.

If you want someone to tell you it's OK to fly, you shouldn't fly today. It's not wise to shop for safety opinions, especially from random strangers on the Internet.
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Great answer......:yes:........:thumbsup:
 
Not a flame.

Just a warning. As pilots sometimes we WANT to fly, no matter what. That's a bad situation, though it probably doesn't seem like it. As you gain experience -- even just a little (I'm only at 250 hours, and I've seen this quite a bit) -- you'll see some very strong pressures to launch that have little to do with whether it really is safe enough for the mission at hand.

Ultimately, you're the PIC and you have to decide if it's safe to fly. And with a new certificate, you WANT to show it off. We've all been there.

But, honestly, I don't mince words about safety, nor do I expect people to mince words with me. It's far, far, far better to have hurt feelings than hurt people. And part of that is never, ever, to censor safety issues. Even if it might be a false alarm. It's just not like other interactions.

And if you ask around, you WILL get all possible opinions.
 
ColeThePilot said:
Well...okay. The other option is to drive 45 minutes north though across a tolled bridge to an unfamiliar airport.

Nobody else has experienced roughness like this?
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From this post it sounds like you value convenience over safety. You're not alone, many pilots seem to feel the same way.

Based on your description of the problem, I'd lean more towards the plane having a vacuum leak causing a lean mixture rather than having an excessively rich mixture. The problem is, what are you going to do about it?
 
Are you looking to get support to go against your flight school? Your safety is your responsibility.good luck ,fly safe.
 
I've flown 3 different aircraft so far, all the same Alarus CH2000. All 3 have a different feel, and sound slightly different. If any of them did what your plane did in flight, and sounded like that, I would immediately head back to the airport and not fly that plane until it was repaired.

My FBO grounded a plane I pre flighted one time because I reported a bald spot on one of the mains. CFI took one look and said no way, so we took another plane. The following weekend, that plane had 2 new tires.

Fly safe.
 
ColeThePilot said:
Geez, I'm so new to this community I've somehow managed to make it sound like I was surrendering a go/no go decision to random strangers! Just wanted to get other, more experienced eyes on it. Sorry.
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Then maybe you should show the video to the mechanics at your FBO. They've got more experienced eyes and can actually do something about it. And maybe show it to your prospective passengers so they can make their own risk assessment before they go up with you in that airplane. Being the PIC doesn't relieve you of the responsibility of informing them about the questionable airworthiness of the aircraft that they will be in. They'll respect your decisions more in the future if they know their safety is your first concern.
 
ColeThePilot said:
I've never had issues starting it. I've raised many concerns about the aircraft at this particular flight school/FBO.

For example...I saw their Cutlass take off with one of it's mains trailing behind the airplane, with the nose wheel and other main retracted. Right away notified them. Nothing was done...and a week later, the airplane made an emergency landing due to a landing gear malfunction.

They seem to write off issues quickly...
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As a renter, I've seen planes with problems (mainly minor), but some FBOs can get jaded, that's for sure. (The advantage of training in this environment is you get used to things going wrong and learn to sort out minor glitches from potentially major problems.) It's hard to know early on in flying what is potentially a real problem and what is not. As suggested above, I would show the video and ask the FBO why they think it's not a problem (sound difference is noticeable). I would NOT show passengers the video & say as PIC "Gee I have my doubts,you really want to fly?" BTW what you've noticed would have gotten my attention too. Do they have another plane you can rent?

Curious about what the pilot making the emergency landing did… He couldn't raise one of the mains and returned to airport with them all down or what?
 
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To bring this back out of the stratosphere of speculation, it's not uncommon for a Lycoming O-360 to sputter a bit when pulled back to flight idle in the pattern, especially on a hot day.

Ours does it occasionally. Leaning a smidge makes it all better.
 
45 minutes and a toll fee or your life... Hmmmm that's a tough question..
 
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Hey you guys, I don't value convenience over safety at all. That's a really unfair statement. Flight safety is extremely important to me. I've written emails, and had a couple of one on one meetings with the FBO manager about things even as little as aircraft documents and registration. I mark up the airplane logbooks, and trust me, I've made quite a bit of fuss.

The other thing that's important to me is my reputation in my local aviation community though. I don't want to be that >100 hour guy who was constantly undermining CFIs and IA mechanics. I was expecting one of two responses by coming here first this time. Either a "get that checked out" OR a "oh yeah, that's been reported in s/n xxxxxx and up, it can be caused by *insert mechanic slang here*. I guess making it seem like I was deferring my judgement was my bad.

WhiskeyPapa said:
Do they have another plane you can rent?

Curious about what the pilot making the emergency landing did… He couldn't raise one of the mains and returned to airport with them all down or what?
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They were able to grab it by reaching back with the tow bar and locking it into place mid-flight from what I heard.

They do have a 172N available, but it has some STC oddities, and I just prefer the R.
 
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jesse said:
I'm curious. What exactly is marking up the airplane logbooks?
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I'd wager he's talking about the hobbs time/discrepancy sheets most FBOs make up and have in the airplanes.



Can't see what you're doing or not doing with the mixture and throttle, but I don't like how that engine sounds. Does the plane have a JPI, it would. Be nice to see if there are any fluctuations in EGT, CHT, and fuel flow.

I'd want a explanation from the A&P as to WHAT causes that sound.

Next time you go up, tell that A&P to saddle up and take him up and show him. I've found that provides a better response.
 
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Well, an uneven running engine means there IS a problem
From your description the FBO owner will express sadness on TV when you and 3 passengers make a smoking hole in the side of some building and will infer it was your mistake

As far as 45 minutes to a strange airport
1. it is only strange until you fly it the first time - the regulars there will think you are a bit touched if you tell them their airport is strange
2. The airport where I keep my plane is 45 minutes away and has been for nearly 50 years and I manage to get there 2 to 5 times a week (leaving in 30 minutes)
 
sounds like classic intake gaskets need replacing. just did mine yesterday. they are chronic issue these days. :mad2:
 
ColeThePilot said:
The other thing that's important to me is my reputation in my local aviation community though. I don't want to be that >100 hour guy who was constantly undermining CFIs and IA mechanics.
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In a word, don't.

Do you really want a reputation of "that schmuck will fly anything?"

Safety culture means you have everyone's back. Which means speaking up. If the organization doesn't support that, you don't really want to be part of it, as something will eventually happen.

This is fairly well understood in the wider community. Occasionally, you run across exceptions, and the rumor mill is not kind to them. Killing customers is kinda bad for business.
 
The first time it happened was when I was a student still. I returned to the airport immediately, and alerted a couple of the instructors there.

The response I got was "That happened once before a long time ago on that airplane, but it cleared itself up."

They went out and performed a run up themselves just to see if they could recreate it on the ground. They couldn't, so they said they'd just relay it to the mechanic and have him take a look at it. The next time I went in, my CFI told me the mechanic cleaned up the plugs. There was a fair amount of gunk deposited on them, likely caused by students not leaning for ground operations.

It then happened once or twice while actually flying with my CFI. I'd look at him, he'd notice, and lean us out a bit more, then we'd continue the flight as if nothing happened.

I remember back on the 172P I solod in, it was almost routine for us to sit in the run up area at 2000 RPM leaned out, because a mag was running very rough. After 2 minutes, another check would prove the engine was running smoothly again. I wouldn't taxi back to the ramp and say flight safety was compromised when this happened. I had to put a fair amount of trust in my CFI because...well, what other choice did I have? I don't have the luxury of leaning on him any longer as a licensed pilot, so I felt like getting opinions around a virtual internet watercooler wouldn't be too harmful. That school up north does look nice though...and it's cheaper. :)

& Yes, that's the book I was referring to. We call it a tach book where hobbs/tach time are logged, and there are areas for comments.
 
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if an fbo refuses or is not able to be on top of sqwaks I wouldn't rent from them. Same way they are trusting you and expect 100% of your care for their 50kish airplanes you are trusting them with your own life. cutting corners is a no no even in trivial stuff. it just shows how much they care about the important stuff. so no I wouldnt fly that airplane until it gets fixed.
 
cirrusmx said:
if an fbo refuses or is not able to be on top of sqwaks I wouldn't rent from them.
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I understand the position… BUT you ain't gonna do much renting if you live by it. You actually learn a great deal renting abused planes (what really is a threat and what isn't).

What do all the other engine instruments say when you have the problem? And what say the forum engine gurus on this one?
 
I haven't noticed any changes in the engine readings. If there are any changes, they only last for roughly 1 second. My eyes go straight to the cowling and my surroundings, since there's somewhat of a vibration associated with the roughness. But I've never seen anything not be in the green in that airplane. If I notice it again, I'll be a bit more assertive with them. You guys are right. I love to fly because of the sense of pride it builds, not some kind of rush. We'll see what happens.
 
MAKG1 said:
In a word, don't.

Do you really want a reputation of "that schmuck will fly anything?"

Safety culture means you have everyone's back. Which means speaking up. If the organization doesn't support that, you don't really want to be part of it, as something will eventually happen.

This is fairly well understood in the wider community. Occasionally, you run across exceptions, and the rumor mill is not kind to them. Killing customers is kinda bad for business.
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Great comment.

The rental 172 I regularly fly gets a lot of hours put on it. So, it often has little things going wrong, and has little problems

I write them all up. Even missing screws in the sheet metal or small cracks in the exterior plastic. (I do ignore wear items on the interior.)

I want the club management to know that somebody is watching.
 
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