I knew that he was he
was going to be very thorough, which is a good thing, but we started off on a
bit of a rough start. I dropped the
plane off on Friday and on Monday he calls and states that the plane would not
be done by Friday because I have a cracked cylinder. My first question was, “did you do a dye
penetration test to determine if it was really cracked?” The response I received was a typical one, “I
have been working on planes for years and this is definitely a crack.” My compression in that cylinder was a 20/80,
so there was definitely something wrong, but it’s a bit unnerving that the
mechanics didn’t trouble shoot and assumed the worst! For those not familiar with this type of
issue, Continental IO-550s (especially Cirrus) sometimes show what looks like a
crack, but in reality they are nothing more than a “dent” or imperfection in
the casting that fills with fuel and dirt and looks like a crack. If a mechanic would clean it up and use
magnafux on it, they would see that it ISN’T A CRACK! From my understanding, many a cylinder have been
replaced over the years because of mechanics inability to troubleshoot and just
jump to conclusions. I guess some people
have super deep pockets and just don’t care, or more than likely they use these
types of expenses as a tax write off.
Regardless, I don’t/can’t work that way!
I learned about this once again from COPA, which in this case saved me
$2500-$3000!
Here is a picture of my cylinder with the "crack" circled in red:
Here are four more pictures of other “cracks” that turned
out to NOT be cracks – see any similarities?
So after some discussion on the COPA forum board, I respond
to my mechanic in a very nice manner. I
told him that I wanted him to clean up the cylinder with scotch bright and then
dye penetrate test the crack. IF it
turns out that it isn’t a crack, then I told him to start the plane up and warm
it up real good and check the compressions again. This time, stake the valve and see if that
helps. I also looked at my EMAX data that
showed my exhaust valve (EGT) working normally for about 15 minutes on every
flight and then cooling off significantly.
My last oil sample also showed a spike in nickel. Nickel us used in the valve guides, so I was
pretty sure I had a valve issue to start with.
I explained all of this to him and sent him back to work. Sure enough, an hour later I get a call. “It’s NOT a crack.” He did the rest and the best he could get was
a 25/80, but he did determine that the exhaust valve was leaking. YEAH!!!
The bad news though is that the cylinder still has to come off to fix
the valve, but that should be significantly cheaper than a new cylinder.
Here is a picture of the cylinder head and you can see the
exhaust valve guides are gone and there is a ton of carbon build up. They will have to lap in the valve and
replace the valve guides to fix this.Other than the cylinder, the aircraft had only minor issues and now is back in service. After picking it up I determined two mechanical issues that will need to be looked at again. The first is the intermittent tachometers. These have come and gone now for six months. It is obviously something loose, since whenever I hit turbulence they come on or go off. They were supposed to fix this at annual and they said they did, but what they did, didn’t work. The second issue is the nose wheel has a wicked shimmy upon touchdown. The mechanic said that the nose wheel was over tightened to 75lbs, when it should be 25lbs. This was done by a Cirrus Service Center because it was shaking all over. The mechanic says that they put it back to 25 and now it is WAY TOO LOOSE! To fix it, they are saying I have to buy four large washers and a Teflon washer –cost around $50. For fricken washers! I will need to look into this some more since this seems a bit extreme for washers.
The last issue I have that came out of my annual is that the mechanics managed to bend my rear baffling wall behind the engine and now you can see the crease. How this happened I have no clue, since it would take a lot to bend this wall of aluminum, but somehow they did. Of course they deny it, but there is no way in hell that it was there prior. It might not look like all that big of a deal, but I don't like my aircraft looking like it's not taken care of. I'm guessing I will just have to live with it, but maybe they will surprise me and do the right thing and repair it.
Overall the plane runs great now, so it’s time to get back at fixing the autopilot!
Your COPA board seems a valuable resource, especially when things like cylinder cracks are a topic of conversation. Shame on your "experienced" mechanic for not knowing what an owner / pilot would know, but kudos for doing the check and admitting his error (though perhaps he only admitted his mistake since you'd get the old parts back and could disprove him THEN).
ReplyDeleteDid the damaged baffle have to come off during the annual? I'm assuming so, since (if it's the same side) the cylinder came off. If so, it would seem not too challenging to push the dent out next time the piece is out of the airplane.
COPA is by far the best $65/year I spend on plane ownership. It really makes sense to become a member of a group like this regardless of what you fly. As for the mechanic, I think he is used to having "businessmen" to work with and when something like this happens, they just go and replace all six cylinders and use it as a tax writeoff. This has been going on for years and just think of how many perfectly good cylinders get scrapped because the mechanics fail to truly determine what the problem is! As for the baffle, it shouldn't have come off since the number four is the middle one on that side, but I'm guessing that the mechanic may have been leaning on it or something while trying to torque down the cylinder bolts or something. I understand that it happens, but what I'm pissed about is that they didn't even bother to mention it and then when I asked, they denied it immediately.
ReplyDeleteLooks like you had an exciting annual. Just starting mine... Let me know what comes out of the autopilot test.
ReplyDeleteFrank
The autopilot is about 95% now. It works great, however I have had it kick off and fail twice in IMC. Both times it was windy and turbulent, so I think I may have a servo issue. We'll see, I'm just going to fly it a while and see what it does. Good luck with your annual Frank.
ReplyDelete