when to do what to props i.e. overhauls

[rbridges]

just reading a thread on mooneyspace and it got me thinking about my prop. It was overhauled in 2002. Looks like an IRAN in 2004. No reason besides routine inspection. It's been inspected during annuals since. Probably has 900 hours on it, but obviously time is the biggest factor.

what are you guys doing with your props? Should I have it IRAN'ed? or go through an overhaul? No leaks and no problems whatsoever, but I don't want to be naive about it. I've read where people didn't like overhauls but would opt for replacement of seals, etc. how would you guys handle it?

 

[Ted]

I wait for the props to tell me there's a problem before I pull them. Mine so far are giving me the thumbs up.

 

[rbridges]

I wait for the props to tell me there's a problem before I pull them. Mine so far are giving me the thumbs up.

Someone mentioned that shops won't touch a prop that hasn't be OH'd after too many years. Is that true? That's the part that worried me the most.

 

[Ted]

Someone mentioned that shops won't touch a prop that hasn't be OH'd after too many years. Is that true? That's the part that worried me the most.

Maybe some shops won't, but generally I've heard they just chastise you for waiting.

Another way to look at it is you could upgrade to a better prop when this one gives out.

 

[nrpetersen]

From what I got from a prop engineer - it depends on the harmonic output from the engine. Specifically, the 4 cyl Lycoming O-360s that do not have a damper on the crankshaft rear are the ones that especially beat torsional hell out of a prop. The purpose of the overhaul is to remove a certain amount of material from the leading and trailing edges of the prop blades to start with new material for fatigue purposes.

In another confirming example, the fixed pitch prop on my brother's Starduster with a 180 hp no-damper engine had a 400 hr mandatory overhaul.

 

[poadeleted20]

For c/s props, a prop overhaul at the same time the engine is overhauled makes a lot of sense. Also, some c/s props have AD's requiring overhaul (or something close to it) and some years/hours interval. Other than that, I'd say do it when your mechanic says to do it.

 

[Stewartb]

My Mac C401 has a required inspection period of five years but as a private guy I'm not required to comply. When this prop was 6 years old I decided to take it to a prop shop for no other reason than it was past the factory recommended time. My prop shop barely saved it. I had internal corrosion in the hub that required a few rather expensive parts be replaced and some corrosion removed. The shop owner told me if I'd waited another year the hub couldn't have been saved. I had no problem that led me to remove it and no improvements in post-overhaul performance. But it saved me a large sum of money so I was glad I did it. Now that I think of it, it's time to do it again.

It's my belief that CS props are the most under maintained component in the GA fleet.

 

[bnt83]

Props are lot like any other component. It may not show any signs of problems but when disassembled you learn the real story. This happens in everything engines, props, landing gears, shimy dampers, hydraulic/pneumatic actuators etc.

All props I'm familiar with have a calendar TBO way less than the engine, usually 60 to 72 months. Many props are way over that.

 

[bnt83]

It's my belief that CS props are the most under maintained component in the GA fleet.

I can think of one that's 15 years since disassembled with a total service life over 30 years. Probably cheaper just to buy new than to ship it where they disassemble and condemn it and have to buy one anyway.

 

[Ted]

For c/s props, a prop overhaul at the same time the engine is overhauled makes a lot of sense.

Or it can make it really hard to find the reason your engine isn't running right when it all goes back together.

I specifically didn't overhaul my props with the engines for that reason.

 

[Henning]

just reading a thread on mooneyspace and it got me thinking about my prop. It was overhauled in 2002. Looks like an IRAN in 2004. No reason besides routine inspection. It's been inspected during annuals since. Probably has 900 hours on it, but obviously time is the biggest factor.

what are you guys doing with your props? Should I have it IRAN'ed? or go through an overhaul? No leaks and no problems whatsoever, but I don't want to be naive about it. I've read where people didn't like overhauls but would opt for replacement of seals, etc. how would you guys handle it?

Ain't broke, don't fix it. Blades firm? No oil leaking? No AD due? No worries.

 

[Henning]

Maybe some shops won't, but generally I've heard they just chastise you for waiting.

Another way to look at it is you could upgrade to a better prop when this one gives out.

Yep, save your nickels and dimes and switch to a more modern design when this one craps or earns an AD that makes it better to just replace.

 

[Tarheelpilot]

My Mac C401 has a required inspection period of five years but as a private guy I'm not required to comply. When this prop was 6 years old I decided to take it to a prop shop for no other reason than it was past the factory recommended time. My prop shop barely saved it. I had internal corrosion in the hub that required a few rather expensive parts be replaced and some corrosion removed. The shop owner told me if I'd waited another year the hub couldn't have been saved. I had no problem that led me to remove it and no improvements in post-overhaul performance. But it saved me a large sum of money so I was glad I did it. Now that I think of it, it's time to do it again.

It's my belief that CS props are the most under maintained component in the GA fleet.

I agree. Most places I have worked send them in for overhaul IAW the manufacturer recommendations and there is always something that was deteriorating and needed repair on a prop that worked fine with no indications of a problem.

 

[flyingmoose]

I wait for the props to tell me there's a problem before I pull them. Mine so far are giving me the thumbs up.

Someone mentioned that shops won't touch a prop that hasn't be OH'd after too many years. Is that true? That's the part that worried me the most.

No they will. If they tell you they wont find another shop. I believe the problem becomes that the longer you wait, the more likely they will not make it through the OH process.
Leaks, use, TIS, etc.. all this into consideration.

It's my belief that CS props are the most under maintained component in the GA fleet.

Agreed.

 

[farmerbrake]

I was looking through some online log books and the one looked like the prop was put on new back in 1997 and hasn't been touched since. It's a 3 blade McCauley.
What would you guys do with that?

 

[Ted]

I was looking through some online log books and the one looked like the prop was put on new back in 1997 and hasn't been touched since. It's a 3 blade McCauley.
What would you guys do with that?

Is it causing a problem? Leaks? Any indications? Do you want to keep it or upgrade as the next step?

 

[Stewartb]

I was looking through some online log books and the one looked like the prop was put on new back in 1997 and hasn't been touched since. It's a 3 blade McCauley.
What would you guys do with that?

I'd have a prop shop disassemble and inspect it. Your shop will advise you of what to do once they see what's inside. You aren't required to overhaul it but it is supposed to be airworthy. I prefer inspection and maintenance to hope and denial.

 

[farmerbrake]

Is it causing a problem? Leaks? Any indications? Do you want to keep it or upgrade as the next step?

Not mine so I don't know. Owner says it hasn't caused any issues YET ...

I'd have a prop shop disassemble and inspect it. Your shop will advise you of what to do once they see what's inside. You aren't required to overhaul it but it is supposed to be airworthy. I prefer inspection and maintenance to hope and denial.

Current owner doesn't Like that Idea. "If i taint broke, don't fiX it."I Personally don't like that with something that is spinning at thousand's of RPM's infront of your face, pulling You through the air

 

[Stewartb]

Yes, the concept that proper maintenance extends a component's life and reduces the chance of catastrophic failure is lost on some guys. But what it really comes down to is they can't bear to pull out their wallets to take care of their equipment. Deferred maintenance is more expensive than routine maintenance in my own experience.

If considering buying that plane? I'd require prop maintenance to be current prior to sale.

 

[farmerbrake]

Yes, the concept that proper maintenance extends a component's life and reduces the chance of catastrophic failure is lost on some guys. But what it really comes down to is they can't bear to pull out their wallets to take care of their equipment. Deferred maintenance is more expensive than routine maintenance in my own experience.

If considering buying that plane? I'd require prop maintenance to be current prior to sale.

Not sure why it's a big deal. the quote for a full overhaul was around 3,000. But it wouldn't necessarily need an OH if they inspected it and thought things looked good right?

 

[Henning]

When you inspect the prop, what do you see? Can you move the blades any in the rotational plane? How far in the longitudinal plane? Can you rotate the blade by hand at all? What climate does it live in?Is it slinging grease? Does it look like the grease zerk has seen a grease gun since 1997? Is it leaking any oil? Does it function well and smoothly through the whole range? How about vibration? Try to have it dynamically balanced. It's cheap, it will always improve things, and if they can't manage to get a good balance on it without extraordinary effort and weights, that can serve as a good indicator that you have problems growing inside the prop.

As for the disassembly and IRAN, it would likely be a good idea, however it is not without risk. A shop will condemn parts that are far from marginal for two major reasons, to make money, and to limit liability. So you may end up replacing a prop that you could have easily gotte another 5 years out of. So you may want to check with the mechanic or prop shop that you have inspect it and come to terms ahead of time as to what level of wear things get condemned at.

Either that or figure you need to replace the prop, have this one pulled and inspected and see what it's going to cost and compare that with the cost to go to a more efficient prop design and decide from there.

Unless you are ready to deal with the cost of replacing the prop now, I wouldn't be taking a zero symptom prop out of service. You would be astounded to see how bad of condition props still work completely safely in compared to how good of props get condemned at overhaul.

 

[Ted]

Not sure why it's a big deal. the quote for a full overhaul was around 3,000. But it wouldn't necessarily need an OH if they inspected it and thought things looked good right?

You can request an IRAN vs a full OH. Keep in mind OH doesn't include new blades or hub, both of which can be found out of limits. Then OH goes way up. A lot of prop shops won't reuse parts that are within limits, either. Combination of limiting liability and making money, as Henning said. You usually can research and find the shops that "always find something" and avoid them.

But, a propeller is a complicated piece of equipment and it can be reassembled wrong. Plus, STC'd props typically have a real benefit in terms of noise, eliminated ADs, and sometimes speed. So it's often worth it to replace with an upgrade.

 

[denverpilot]

You can request an IRAN vs a full OH. Keep in mind OH doesn't include new blades or hub, both of which can be found out of limits. Then OH goes way up. A lot of prop shops won't reuse parts that are within limits, either. Combination of limiting liability and making money, as Henning said. You usually can research and find the shops that "always find something" and avoid them.



But, a propeller is a complicated piece of equipment and it can be reassembled wrong. Plus, STC'd props typically have a real benefit in terms of noise, eliminated ADs, and sometimes speed. So it's often worth it to replace with an upgrade.

Just as a point of data: Rocky Mtn Propeller won't do IRAN anymore. They overhaul everything completely now. Don't know if it was for efficiency or liability or just to simplify their world, but they said on the phone a while back they simply aren't interested in IRAN business anymore. They'll have it done and back in only a few days if you pre-arrange a date with them. They'll even throw it in their pickup truck and deliver it across town if you're a local.

 

[coloradobluesky]

I had a prop that was slinging grease (just did it one time). I sent to the prop shop, nothing wrong with it. Guy at the prop shop said "next time must wipe it up, sometimes that happens". Gee, that was $3500 down the tubes (more than that actually, all things considered).