overhauling cessna prop

Tom-D said:
Get real.
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Right. :rolleyes: You jump on the first thing that comes to mind, an incompetent A&P based on a forum post from a customer with very little data.

And how much experience do you have with the OP? Do you know the OP?How do you know the OP isn't the one that can't communicate well? After all pilots are great relayers of maintenance jargin...

As usual Tom blowing smoke and running at the mouth with "If your mechanic cannot ________________ they need to be fired!"
 
bnt83 said:
Right. :rolleyes: You jump on the first thing that comes to mind, an incompetent A&P based on a forum post from a customer with very little data.

And how much experience do you have with the OP? Do you know the OP?How do you know the OP isn't the one that can't communicate well? After all pilots are great relayers of maintenance jargin...

As usual Tom blowing smoke and running at the mouth with "If your mechanic cannot ________________ they need to be fired!"
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Often times it's true though. There is no shortage of incompetent mechanics out there and that's one of the things that drives the cost of GA through the roof. A bloody monkey can turn wrenches, and anyone that can follow instructions can do the paperwork, however diagnostics is where the majority of mechanics fail hard.
 
Ben,
Yes, I told them right off that I had the credentials, and I
was only trying to be fair to the person I was selling it to.
I gave the buyer the option if the took it to a prop shop and it was
condemned I would return their money.
Dave
 
OP here, my mechanic thought the plane had more vibration than it should when running the motor up on the ground. He hasnt flown in the plane. He thought the ballance was out a bit on the prop, but from what I am reading that could be a few other things as well.

I am confused, is it possible to clean up and paint the prop (not overhaul it) and then reballance it without having to send it to a specialized shop. Can the tracking be adjusted too without sending it out ?
 
And I thought I would add... Ive had the plane for about a year. I havnt noticed vibration getting worse. I did seem to notice where the vibration in the motor seemed to change during flight. It seems like sometimes it might be smoother than other times, not sure if it really is tho.

My plane is really clean, has a penn yann motor 10 yrs old with only 325 hours on it. Has mags from 10 yrs ago when motor was installed. I did go to mechanic because I had a few times when I was flying where the motor seemed to run a bit rough for a few seconds, would vibrate heavy, then smooth out lasting about 15 seconds. Checked compression, all above 78, plugs were clean. Through tipping the plane and shaking it we found a good bit of water in one wing and attributed the bit of roughness i experienced to either the water contamination, carb icing, or the mags.

The mechanic is suggesting I have the mags pulled and inspected/overhauled, to overhaul the prop, and to possibly inspect the carb and clean as neccesary.

He was convinced that would get the plane running at tip top condition, smooth out any roughness, and insure the value of the motor. I am just not too happy about having to shell out the bill. I trust the mechanic tho, as he has helped me a lot off clock and he doesnt seem like the kind of guy to take me for a ride.
 
That vibration likely isn't the prop, but still at 10,000 hrs I would want to know my blade dimensions relative to limits, and would be prepared to condemn the prop, but not for the vibration. Out of curiosity, what is your static RPM?

Sounds like there may be a little shotgun troubleshooting going on here, but in your mechanics defense, intermittent problems are very tough to chase down.
 
bobkiksass said:
And I thought I would add... Ive had the plane for about a year. I havnt noticed vibration getting worse. I did seem to notice where the vibration in the motor seemed to change during flight. It seems like sometimes it might be smoother than other times, not sure if it really is tho.

My plane is really clean, has a penn yann motor 10 yrs old with only 325 hours on it. Has mags from 10 yrs ago when motor was installed. I did go to mechanic because I had a few times when I was flying where the motor seemed to run a bit rough for a few seconds, would vibrate heavy, then smooth out lasting about 15 seconds. Checked compression, all above 78, plugs were clean. Through tipping the plane and shaking it we found a good bit of water in one wing and attributed the bit of roughness i experienced to either the water contamination, carb icing, or the mags.

The mechanic is suggesting I have the mags pulled and inspected/overhauled, to overhaul the prop, and to possibly inspect the carb and clean as neccesary.

He was convinced that would get the plane running at tip top condition, smooth out any roughness, and insure the value of the motor. I am just not too happy about having to shell out the bill. I trust the mechanic tho, as he has helped me a lot off clock and he doesnt seem like the kind of guy to take me for a ride.
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Do you have Slick mags? If so, make sure your magnetos are not affected by the soft carbon brush issue http://www.aeronca.org/Slick-SB3-08.pdf, regaurdless of the vibration issues.

Are you burning car gas or 100LL? Just wondering about fuel quality. The water might have been the problem.
 
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bnt83 said:
Do you have Slick mags? If so, make sure your magnetos are not affected by the soft carbon brush issue http://www.aeronca.org/Slick-SB3-08.pdf, regaurdless of the vibration issues.

Are you burning car gas or 100LL? Just wondering about fuel quality. The water might have been the problem.
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Depending on how precise the 10year number is he is just ahead of the affect manufacturing times for that one, but the mags are not a bad place to look for intermittent issues like he describes.

The $1,000,000 question, any issues after getting the water out?
 
Awe hell, let's just remove all this stuff and send it in for overhaul, there's no trouble shooting necessary.
 
Tom-D said:
Awe hell, let's just remove all this stuff and send it in for overhaul, there's no trouble shooting necessary.
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If the manufacturer will NOT provide servicable data points to an IA so they can confirm the prop is airworthy, then sending it in must be the only option....

I still contend that a aircraft parts manufacturer should be required to provide service limits to A&P IA Professionals... Hard to believe the FAA puts up with this unsafe situation.
 
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N801BH said:
If the manufacturer will NOT provide servicable data points to an IA so they can comfirm the prop is airworthy, then sending it in must be the only option.....
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Have fun reading...

Blade Track Check, page 612. If fails send to Authorized Repair shop

Blade Repair, page 801

Blade Painting, page 806

Prop Vib Troubleshooting, page 105

http://www.mccauley.textron.com/MPC26OWrev2.pdf
 
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N801BH said:
If the manufacturer will NOT provide servicable data points to an IA so they can comfirm the prop is airworthy, then sending it in must be the only option....

I still contend that a aircraft parts manufacturer should be required to provide service limits to A&P IA Professionals... Hard to believe the FAA puts up with this unsafe situation.
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The manufacturers place their data in the overhaul manuals which they sell, that data can be used by any one who has a manual. The prop overhaul manual is a required item by the shops that are allowed to do the repairs, we A&Ps are not allowed to do any thing other than minor maintenance on props, So most of us do not have a manual for each and every prop we see.

But as an A&P we should have knowledge of who and when we should call when in doubt. And of course what is minor and major maintenance on props is fundamental "prop 101" in school.
There are too many makes and models each with their own set of ICA's to make a flat statement as to what any one can and can't do to props.
 
The times when it ran a bit rough, there were 3 times it happened, each lasted about 15 seconds.... it happened only once each flight that was about an hr long.... the flights were in conditions where there was fog around (high humidity) .... After pulling water out of the wings last weekend, I flew for an hr and did not notice the roughness or loss of power. Its possible it was carb icing or the water in the fuel that caused the roughness on the past 3 flights, but not positive.

Not sure if they are slick mags.... I did receive a service bulletin from cessna regarding the mags about 5 months ago. I showed it to the mechanic, and he suggested due to the service bulletin and the 10 yrs on the mags that it was advisable to have them overhauled, this was before I had the few times encountering intermittent roughness of the motor.

The vibration in the prop was noticed by the mechanic a few months ago, at which time there were no other issues as noted above.... he just recognized that there was a bit more vibration than should be when running up on the ground.
 
N801BH said:
If the manufacturer will NOT provide servicable data points to an IA so they can comfirm the prop is airworthy, then sending it in must be the only option....

I still contend that a aircraft parts manufacturer should be required to provide service limits to A&P IA Professionals... Hard to believe the FAA puts up with this unsafe situation.
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The prop shops I've dealt with will scan/fax whatever relevant dimensional information to the mechanics for the purposes of checking the blades. In Canada we have a five-year corrosion inspection requirement, so the prop comes off and gets a good check, and the blade widths and thicknesses are checked at the specified blade stations.

The prop shops had all the manuals they needed, bought by subscription from the manufacturers. I bought all my own for our shop. If I was still there I'd be able to get at it.

Dan
 
bobkiksass said:
OP here, my mechanic thought the plane had more vibration than it should when running the motor up on the ground. He hasnt flown in the plane. He thought the ballance was out a bit on the prop, but from what I am reading that could be a few other things as well.

I am confused, is it possible to clean up and paint the prop (not overhaul it) and then reballance it without having to send it to a specialized shop. Can the tracking be adjusted too without sending it out ?
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The Maintenance Fairy can do anything.
 
bobkiksass said:
Not sure if they are slick mags.... I did receive a service bulletin from cessna regarding the mags about 5 months ago. I showed it to the mechanic, and he suggested due to the service bulletin and the 10 yrs on the mags that it was advisable to have them overhauled, this was before I had the few times encountering intermittent roughness of
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The carbon brush service bulletin would not apply to Bendix mags so if he said it applies you have slicks. DO NOT EVER ask for an overhaul on Slick magnetos, it just isn't cost effect with a distributor block around $350 each. Just get them Inspected and Repaired as Necessary (IRAN).

Replacing the carbon brush is easy BTW. After the mag is on the toolbox it's a 10 minute job with a quick once over look at everything else in there. So like 2 hours R&R both mags with brush replacement. Brushes cost about $5.

But brush failure can trash a mag. Pulling the harness off the back of each mag and look at the distributor block for black soot like dust. You shouldn't even have to pull them off the engine to do just that.
 
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RotorAndWing said:
And no shortage of Internet "experts" claiming vast maintenance experience with no ratings to back it up.............

Just saying.......
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If they'd let me take the test, I'd have the rating. I haven't got the time or money for 2 years of school and they say my experience isn't recent enough.:dunno:
 
Henning said:
If they'd let me take the test, I'd have the rating. I haven't got the time or money for 2 years of school and they say my experience isn't recent enough.:dunno:
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BS pal, there is no recency of experience for the A&P. Perhaps a problem documenting all of your "experience".
 
RotorAndWing said:
BS pal, there is no recency of experience for the A&P. Perhaps a problem documenting all of your "experience".
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Incorrect, when she pulled out the book to see if she could sign me off she told me my experience from the 90s was 'too old' and I hadn't had any experience within x amount of years, I forget what x was.
 
Henning said:
Incorrect, when she pulled out the book to see if she could sign me off she told me my experience from the 90s was 'too old' and I hadn't had any experience within x amount of years, I forget what x was.
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Once again, BS. There is no such requirement in "the book". All historical orders are on file in FSIMS, and recency of experience has not been a requirement for A&P in any of them.
 
My prior supervisor just got signed off for all 3 tests with a Spartan school graduation certificate dated 1964.
 
Bob:

If you can provide the model number of your prop, I'm pretty sure I can get you the dims you need.
 
prop is mccauley 1b90. If you give me the dims then maybe my mechanic and I can measure to see if its in check.

I noticed the vibration in the plane seems to be worse when at high pitch, full power. At level flight with 2500 rpm, not so bad. But when full power at high pitch it seems like the vibration grows worse, not sure if its because the plane is going slower, but really the vibration is most affected by the pitch of the plane not power settings.

The times when the motor ran rough were all at high pitch, on climbout, and it seemed like the vibration would start then the motor would noticeably lose some power. Can the prop being out of ballance make the motor lose a small amount of power ?

Does that tell you anything about whether it is my prop causing the vibration ?

And I do have slick mags, so I am thinking I should have them inspected to be sure they are covered by the advisories currently out.

Thanks
Bob
 
bobkiksass said:
And I do have slick mags, so I am thinking I should have them inspected to be sure they are covered by the advisories currently out.

Thanks
Bob
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Why not look yourself?

Do you have your logbooks? If so, can you find an enry that shows the serial # of the magnetos installed? If not pull the top cowl and get the serial #'s off them

#1 If the serial # isn't 0409XXXX and UP then go to #2,

#2 Look any entry that shows the mags being removed, disassembled, inspected, distributor block preplaced or carbon brush replaced after september 1, 2004.

http://www.aeronca.org/Slick-SB3-08.pdf

 
Does anyone know what years of manufacturing the Slick Mag advisories apply to? I am unable to locate serial number. My motor and mags are 10 years old, is it safe to assume the advisories apply to my mags ?
 
Capture33_zpsf67a578b.jpg



COMPLIANCE:

• For all magnetos with serial numbers 0409XXXX through 0611XXXX, and all magnetos
that have had a carbon brush or distributor block replaced between September 1, 2004
and November 30, 2006 perform Compliance Steps 2 and 3 only.
• For all magnetos with serial numbers 0612XXXX and UP, and all magnetos that have
had a carbon brush or distributor block replaced on or after December 1, 2006, perform​
Compliance Steps 1 through 3.
 
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I had a vibration problem on a 150J. It was awful, and would vary in intensity with rpm. We checked the ignition system, the fuel system, IRAN th' carb. Checked compression, hot, cold, warm, indifferent, and otherwise. All checked out well, and still vibration persisted. I took it upon myself to pull the prop, chuck it up in the balance stand, and give it a spin. It would stop in the same spot with the same blade down. I checked it for track, and it tracked true. (at the tips) But when sighting down it I could see that something wasn't quite right. And feeling down the blade I could tell that there were unlogged repairs. Hmm. On a lark I checked runout at midway of the blade, and there it was. I also found that in the TCDS there is info that is useful in determining whether or not the prop was junk or useable (repairable).
I could have done the repairs myself, but elected to send it out to Sensenich, It was plenty long enough, but it had been treated pretty rough.
For $375 they had it back to me, and vibration went away. They told me what I had suspected all along. One blade was badly out of "twist", and bent, and one blade was shorter than the other. Luckilly the profile had not been molested too badly.
Which only served to confirm what I had suspected all along, since I first saw it with the cowling off.
Prop Strike! repaired, and not logged.
 
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