The International Cessna^® 170 Association

I just pulled my o-300/c-145 due metal through my screen. It came from wrist pin caps on the piston. I recently pulled number 3 cylinder due a stuck ex valve and found a little ball of aluminum on one side of the piston wrist pin. It was a disintegrating cap. It was fixed and I flew another 20 hours to get low oil pressure. It was caused by aluminum flakes in the screen to the point of clogging it. I found al flakes in 5 of the 12 rocker arms in the oil passage centered on the rocker. On pulling Number 2 cylinder there was a missing cap on the rear side of the wrist pin, the pin had staked its position and the piston around the cap was shiny with some deformation besides the staking. My AI told me, finally, there was a Mandatory SB about wrist pin caps and a brass replacement was required. He has later told me he was wrong after we look at the repaired cylinder with a Aluminum replacement, not brass as he had suggested. I had sent off an oil test on the stuck valve repair only never to hear from them again. Just throw them money for what? A failure

What the heck is going on? You cannot have disintegrating end caps in certified airplane engines. I have 12 possible engine failure makers that cannot be detected until you have an oil change. Then the only way to find the cylinder or cylinders with aluminum BB's inside you have to pull each cylinder, and all cylinders. My AI says this happens within 2 hours, fast when they fail. Are these failures time, engine time related? What is going on? And is there a real fix? This is the screwiest mess I have ever heard of. How is this a mandatory SB and not an AD? And why am I the first to have this? I could find nothing in the search of your articles.

I bought a 170 from the previous owner in CA this past winter. Prior to this the airplane sat for 2 years. I put 77 hours on the airplane in the last 6 months, part of that time flying it up from central CA to Anchorage AK. All was good, no issues then:

I had my mechanic do a routine check of my plugs before embarking on flying my c-170b with 0300-C engine out of alaska. We changed the oil and also checked the screen and found to our chagrin many pieces of shiny metal flakes covering the screen. We found the flakes to be non-ferris. The flakes were very flat like shavings. The mechanic cleaned out the case making sure to pick up any pieces inside, we put it all back together and I flew the airplane hard at 2450 RPM for 10 hours on the tach. We pulled the screen after flying it and there was only one piece of metal on the screen and two pieces in the bread pan the mechanic used to catch some of the oil when he pulled the screen. Through this whole process there has never been any fluctuation in oil pressure as one may assume with metal on the screen. This was actually good news since there were many less pieces then before 3 vs perhaps a hundred. We also took a Lab-1 oil sample. The sample came back normal with all the numbers low compared to other samples I have seen from other owners. Then my friend (also a 170 owner) sent me this thread and now I am really worried. Could I have issues with my wrist pins and a contaminated engine? Should I pull the cylinders and check the wrist pin caps? Lets say I found one or move are not longer there, would I have to pull the accessory case to check for metal there? I flew the airplane the other day, all is good, but am I lulled into a false sens of security by what seems to be a smooth running engine?

anybody else that can add some insight here would be helpful

I'm scared to pull the cylinders because of the Teledyne AD 94 05 05 R1 that will require me to check the cylinder rocker shaft bosses for cracks once the cylindres are off the engine. My mechanic advices me that from experience if I send the cylinders off to the engine shop they will most likely not pass inspection and then I am looking at all new cylinders. The mechanic did not recommend nor did the engine shop advise that we should do anything other than run the engine for another 25 hours and check screen.

Additionally I was advised to read the Lycoming engine tech tip booklet to advise on what do if I found metal flakes in the screen or filter. (the reason I was told to read Lycoming was because they are more conservative with their advice than Continental). In the booklet it says the following under the heading: "Suggestions if metal found in screen or filter": then under examples (which my find I believe falls under): "Example: Several pieces of shiny flake-like, nonmagnetic or several pieces of short hair like pieces of magnetic material - place aircraft in back in service and again check oil screen of filter in 25 hours."

I don't know this a roller coaster. Maybe I can just jump to the future and put an electric motor on the darn thing

res3d wrote:I'm scared to pull the cylinders because of the Teledyne AD 94 05 05 R1 that will require me to check the cylinder rocker shaft bosses for cracks once the cylindres are off the engine. My mechanic advices me that from experience if I send the cylinders off to the engine shop they will most likely not pass inspection and then I am looking at all new cylinders. The mechanic did not recommend nor did the engine shop advise that we should do anything other than run the engine for another 25 hours and check screen.

Well the AD can be complied with by your mechanic. The cylinders do not have to go to a cylinder shop.

Your logic doesn't make sense. You are afraid to pull cylinders because they might be found to be bad and you would rather not know and just keep running them. And this fear is keeping you from performing an inspection for a symptom (metal) which you think may not be normal.

I'm not advocating pulling cylinders at the first sign of metal. I'm just saying I would fear it to the point of engine failure.

From ThomasRS: Things have developed. The engine has set for too long, around 15 years. It has recently run well, due preserving but it was past the TBO of 12 years even though only 600 hours. Of course we have torn it down and it was looking good for a smooth overhaul. Shop man said I would have been the first to pull all cylinders when I found a disentegrating pin cap on #3 and flew 20 hours before the additional pin cap on #2 disentegrated as well. Shop said wrist pin stiffness even though lubricated did in the wrist pin cap. I totally agree that replacing the caps should be done on any cylinder removal. Fatigue and rubbing due pin to piston stiffness are what helps pin cap failure along. I recommend if you see those pretty aluminum flakes, just pull all cylinders and do not wait. Caps can disintegrate in less than 1 hour of flight. Any filter will ultimately bypass when clogged with aluminum, and that happens quick.

Now however the engine is scrap regardless. Before I bought the aircraft there was a logbook entry, pulled #4 and #6 due low compression(a lie). Less than 200 hours of flight later we realized engine time had been fudged so we zero timed it. They had pulled #2 and #4, not #4 and #6 because of a rod failure or swallowed valve. At the OH we found a locked harmonic balancer on the crank rear and a cracked piston on #1. Now 400 hours later, on inspection of the case an alert shop man who heard of the stiff balancer looked directly at the rear bearing support on the case and found a barely visible crack totally through the support and all the way to an existing hole for oil splash. He looked there first due the locked harmonic balancer causes the rear bearing support to fail. He sees this every time. It was missed on the zero time but was always there for the additional 400 hours of flight, waiting to come apart.
I am presently looking for an new o300 or C-145. The joy of aircraft. Any recommendations for a new engine source?

I hear ya on all this, but I am getting some experienced people on the ground here including an experienced long standing engine shop that would love to rebuild my engine, saying that should not pull the cylinders and that I should run the engine and check the screen every 25 hours. the last check I did of the screen there was only one piece (flake), the oil analysis came back normal, granted there is something going on, most likely the wrist pin caps, and that is the consensus amongst the mechanics I am talking to, but they are all reluctant to start pulling things apart.

ThomasRS,
I have a C-145 engine for sale for$2500 FOB Sacramento, CA. If you're interested, call me at 916-635-5566 ---PM --- blueldr@gmail.com.

As the old saying goes " When the fan stops , the pilot will sweat'' . If on the ground and you find what you do not want to find you can push it in the hangar and go have a cold beer. OR 2 . Knowledge is golden.

My 172 with a 0-300D has had the cylinder AD complied with about 285 hours before I bought it. The yellow tags were with the log books. I can't remember which brand cylinders it has, but they have a different valve angle on the intsake than the specs I looked up. When we had the cylinder off we took it to my shop and checked all the sizes and specs. I did a light touch up hone on it and honed both valve guides to the correct size. I have the equipment to hone guides and measure them down to .0001--- That is right, not too many zeros. The same with bore sizes. Back to the intake valve seat angle. As close as I could measure it was on a 30 degree angle and the ex was on a 45 degree angle. The specs I have say both should be 45 degree. I'm also wondering if the specs are wrong. I found everything in spec and very good shape except for the lead deposits built up in the ex guide.
When we had a cylinder off for a stuck ex valve and I do remember noticing the pin buttons were gold in color and appeared to be some grade of brass. I have one of the aftermarket filters that I plan to put on the engine. An a&P I know cautioned me about taking out the primary sump screen. He says it should be left in to catch any BIG pieces of whatever decides to fail. He says it also protects the oil pump from being eaten up by any large particles of engine parts, since it is on the suction side. He says the filter is on the pressure side of the pump. That is how most automotive systems are done, too. I haven't had time to study the oil system flow and passages to see if he is full of BS or telling it like it is. You can bet that $50 that I will study things before I add the auto type filter and check the primary screen when I change oil. (if it is best to leave it in)

TCM issued a bulletin addressing piston pin plug wear patterns...but it DID NOT APPLY to our C145/O300 engines.
For information/education purposes only.... and to provide a guideline for this discussion, here is a copy which includes pictures of their concerns on OTHER engines:

This is another Ford/Chevy thing. There is probably no right or wrong answer, you have to go with your gut. The experience is saying run it and watch it because they have seen more things taken apart prematurely.

I've been there, torn stuff apart without or against the opinion of experience and wished I hadn't.

Learning from those experiences I've run stuff way past what I should have trying not to be to conservative but ended up paying a higher price.

So what I suggest is get educated which you are doing in part here at this forum. Take all advice and weigh it. I'd give more weight to the experience who have actually seen the amounts of aluminum. Then go with your gut and don't look back.

Aryana wrote:[...I would at the very least stick one of those Harbor Freight borescopes ($180, exact same as the one Aircraft Tool Supply sells for $300) in each cyl through the spark plug hole and carefully inspect ...

If I'm thinking of the same tool you are mentioning.... I'd advise caution on buying one of those hand-held camera type tools. They do not allow viewing "aft" without a mirror attachment....which usually FALLS OFF or disintegrates, or the camera-head comes apart ....leaving parts inside the cylinder and necessitating cylinder removal.

Sometimes a cheap tool is all you need for a one-time job... but this one has bad reviews for the reasons mentioned. (Customer reviews are available at the HF website which will confirm these comments.)

I have looked inside cyls pretty effectively by removing both spark plugs, and inserting an inspection probe-light in the lower plug-hole and using a small dental mirror in the other .... but a real boroscope (not a cheap tool) is the real answer. Perhaps a trip to the airport might lead to permission to borrow....

While there are those who like it (I guess it depends on individual experience)....Straight from Harbor Freight website...here is the most popular FAVORABLE review of that device:
"Most Liked Positive Review:

Caution! Mirror attachment falls apart!

CAUTION MIRROR ATTACHMENT COMES APART! The first time I used the mirror attachment to scope cylinders on my airplane engine the little mirror fell out of the attachable tip inside a cylinder. I was ...Read complete review
CAUTION MIRROR ATTACHMENT COMES APART! The first time I used the mirror attachment to scope cylinders on my airplane engine the little mirror fell out of the attachable tip inside a cylinder. I was able to fish out the little mirror, crazy glue the two parts of the tip together and it worked great. I was very lucky that I did not have to pull the cylinder apart to get it. Hopefully this post will save someone the grief of loosing the mirror in a place you can't get it easily. Crazy glue the 2 parts of the mirror attachment before you use it."

Here's another review:
8/23/2012 1.0couldn't view dark places
By Meen Gene

from Arlington, tx
"No switch to turn on leds

Comments about Cen-Tech High Resoltuion Digital Inspection Camera with Recorder:

Unable to find out how to turn on the LEd's for viewing in a dark place.

Bottom Line No, I would not recommend this to a friend"

And another:

Mechanic Don

from Cincinnati Ohio Store number #122

About Me Auto Enthusiast, Mechanic, Truck Enthusiast
Pros

Easy To Use
Cons

Instructions Not Helpful
Poor Value

The picture was terrible. The light blinds out the picture. I turned it down and it still was poor at best.I returned it two days after I bought it and they charged me 20% to return it .I will never buy anything that charges you to take it back. It seems this is a new policy that Harbor Freight has gone to to cover cost of the junk they sell.Do Not BUY If There Is A Restocking Fee.

Bottom Line No, I would not recommend this to a friend"

And another:
WEEKEND WRENCHER

from MICHIGAN

Breaks Easily
Poor Value


90 DEGREE MIRROR ATTACHMENT FALLS OFF WITH ANY BUMPING OR USE. FELL OFF INSIDE THE CYLINDER I WAS INSPECTING ON A JET SKI. FIRST USE RIGHT OUT OF THE BOX. TRIED FISHING IT OUT WITH MAGNETS WHICH IS HARD AS ITS NOT EASY TO GET IT ATTRACTED TO A MAGNET. WE HAD TO PULL THE CYLINDER HEAD TO EXTRACT IT. IN PROCESS OF SLIGHTLY FLEXING THE HEAD THE INTERAL WIRES CAME DISCONETED FROM THE CAMERA. I HAD TO RETURN IT TO HB FOR ANOTHER ONE TO TRY TO FISH IT OUT OF THE MOTOR! NEW OUT OF THE BOX I PULLED GENTLY ON THE CAMERA ATACHMENT AND IT FELL OFF! THE SECOND UNIT. BASICALLY NO GLUE HOLDING IT TOGHETER. SO I SUPER GLUED IT AND TRIED TO GET IT OUT OF MY MOTOR BUT COULDNT. WE HAD TO PULL THE CYLINDER HEAD TO EXTRACT IT. TONS OF TIME/LABOR WASTED. ALSO THE VIDEO STARTED GLITCHING AGAIN FROM FLEXING THE HEAD 10-20 TIMES IN TRYING TO SEE THE PART. WE NEVER FLEXED THE HEAD OVER 20-30 DEGREES EITHER AND WERE NOT HARD ON IT. NOT ONLY IS THE [$] WAST OF MONEY, BUT IF THAT MIRROR FALLS OFF INTO YOUR MOTOR THAN YOU CAN HAVE THOUSANDS OF DAMAMGE OR TIME TO REMOVE IT!!! GO TO HB FREIGHT. OPEN OF THE BOX, AND SIMPLE PULL GENTLY ON THE CAMEAR ATACHEMNT ENDS AND IT WILL FALL RIGHT APART. SHOW THEM IN PERSON SO PEOPLES ENGINES DONT GET SCREWED UP. READ OTHER REVIEWS WITH THE SAME PROBLEM! OR FIND OUT YOURSELF!!!!!!!!

Bottom Line No, I would not recommend this to a friend

(0 of 1 customers found this review helpful)

Meanwhile... if you don't mind using one that attaches to a laptop for power and for the video / recording on hard drive, Northern Tool sells one for $69....:


http://www.northerntool.com/shop/tools/ ... _200512626

They also sell other types.

Aryana wrote:Here is a preview of what to expect when only 1 plug decides to depart from your pin and crushes the pressure oil screen.

I had one that looked just like that on our return from the Detroit convention. Replaced whole engine with a used one in better shape. Somewhere in my after life, I remember an old engine rebuilder mentioning something about the bores in the piston rod were not exactly parallel which caused pressure on the piston pin plug. Anyone ever heard of this ?? Over the last 42 years, I've had two do this. It's really bad when you go to check your oil and it looks like silver paint.