Prop Overhaul And Maintence

[base698]

How much do they cost and about what hour mark does it need it?

[cujet]

Many props have 5 or 6 year suggested overhaul periods. Also, sometimes as short as 600 hour suggested increments. But, that depends greatly on the prop in question. 

 

2 blade props generally cost less than 3 blade props. $1600-$2200 for 2 blade props is the norm around here. $2000-$3000 is the local norm for 3 blades. 

 

Here are a few thoughts: 

 

I'm not a fan of overhauling props needlessly. At each overhaul, there is often a requirement to remove a certain amount of surface material. Sometimes it's as much as thirty thousandths of an inch. (about double an aviation spark plug gap). Once this is done a few times, sometimes as few as 3 times, the prob blade can be "too thin" and gets rejected. 

 

Sometimes, a prop can get a "re-seal" where just the O-Rings and seals are changed, and a general inspection is performed. Note, some prop shops won't perform a re-seal on props more than 6 years from last overhaul. Some shops go 10 years. I don't know of any who will perform a re-seal on a prop that has an overhaul older than 10 years. As you might guess, a proper re-seal can go a long way towards extending the life of your prop. 

 

My prop was built in 1974, overhauled once since then, and resealed twice. I just recently sent it in for it's 2nd overhaul. It was in great shape, and good lord willing, it will make it's 3rd overhaul sometime in the distant future. Had it been overhauled every 6 years as suggested, the prop would long ago have been scrapped. 

 

Also note: depending on prop model, there may be some other reasons to overhaul. Such as known crack risk in the hub, corrosion problems, leaks, and internal parts that need updating due to age or design. 

[Guest]

Typical prop overhaul time per s/b 72 calendar months and anywhere around 2200 hours. Budget 1000 per blade and more if it has deice.

Clarence

[John Pleisse]

1500/5 years on my 201. I ran mine until it leaked, 800/10. Careful, the OH is easy. Competent A&P talent is a must. Pre J's have a firewall plate that is removable, giving your guy lots of room for R&R. 201's there is no room. Another helpful caution, some gov's have muti small screw attach points on the control arm. The are screwed directly into areas of higher oil pressure. Most OH shops don't seal these requiring your guy to rubber washer and seal them. If they don't do it, you'll have oil on your FW. Also, be sure to check oil pressure line flanges...they crack easy from vibration. The blades and front should be easy-peezy.

[RobertGary1]

No real reason to "overhaul" them. The TBO is like 20,000 hours now. But a prop shop can dress,repaint, and measure the blades. The hub should be reworked. Adding the word "Overhaul" adds more than is necessary and most shops seem to be discouraging it now.

 

-Robert

[Guest]

I think 20,000 hours may be optimistic. McCauley sb 137AF and Hartzell HCH-SL-61-61Y cover the respective propellers.

Having the propeller disassembled and inspected is a good way to avoid unexpected problems. During a PPI and overdue propeller can become a stumbling block.

Clarence

[Marauder]

No real reason to "overhaul" them. The TBO is like 20,000 hours now. But a prop shop can dress,repaint, and measure the blades. The hub should be reworked. Adding the word "Overhaul" adds more than is necessary and most shops seem to be discouraging it now.

-Robert

That is what I thought as well, but this is what happened to a friend of mine... He survived and lived to tell me the tale. He told me the vibration was so bad that he could only shut the engine off by running his hand down his left leg to reach the mags. I think they should be inspected periodically.

http://www.ntsb.gov/_layouts/ntsb.aviation/GeneratePDF.aspx?id=NYC99LA202&rpt=fi

[ryoder]

So they recommend blade corrosion inspections. I never really thought about that. Is that done? My prop was majored in 1984.

[Marauder]

So they recommend blade corrosion inspections. I never really thought about that. Is that done? My prop was majored in 1984.

If your prop was inspected 31 years ago, I would have it looked at. The guy in the accident above is a mechanic. He rebuilt his engine under the supervision of an IA. He never did anything with the prop... Something to think about.

[jetdriven]

Wen our prop was resealed it was 12 years old and had 1250 hours since new. They dressed the blades, stripped, painted them and reassembled the prop. What they did not do was grind the blades or NDT test the hub. But it was low time and looked new inside so why bother.

[RobertGary1]

That is what I thought as well, but this is what happened to a friend of mine... He survived and lived to tell me the tale. He told me the vibration was so bad that he could only shut the engine off my running his hand down his left leg to reach the mags. I think they should be inspected periodically.

http://www.ntsb.gov/_layouts/ntsb.aviation/GeneratePDF.aspx?id=NYC99LA202&rpt=fi

Calling the inspection doesn't change that. You can still have all the same inspections. You just don't have to meet all of the overhaul limits. The prop shop can determine if the prop is safe.

[Guest]

Just look at the number of ADs on propellers, most cover cracking issues, blade failures etc. There is obviously just reason for having your propeller disassembled and thoroughly inspected. Whether you call it an overhaul is up to you.

Clarence

[ryoder]

If your prop was inspected 31 years ago, I would have it looked at. The guy in the accident above is a mechanic. He rebuilt his engine under the supervision of an IA. He never did anything with the prop... Something to think about.

One good thing is that my prop requires the 100 hour eddy current inspection. That is coming up and I am going to talk to the inspector about doing a more thorough inspection and repaint if appropriate. It doesn't have many hours on it since the prop strike in the 80s.

[mike_elliott]

That is what I thought as well, but this is what happened to a friend of mine... He survived and lived to tell me the tale. He told me the vibration was so bad that he could only shut the engine off by running his hand down his left leg to reach the mags. I think they should be inspected periodically.

http://www.ntsb.gov/_layouts/ntsb.aviation/GeneratePDF.aspx?id=NYC99LA202&rpt=fi

I am curious if this is one of the supporting accidents initiating the eddy current inspections of the non B hubs. Did he keep it hangered in KELM or was it tied down there. With the finger lakes right there, Elmyra can be a harsh environment if outside I would think. He is a lucky guy to be breathing today. 

[Marauder]

I am curious if this is one of the supporting accidents initiating the eddy current inspections of the non B hubs. Did he keep it hangered in KELM or was it tied down there. With the finger lakes right there, Elmyra can be a harsh environment if outside I would think. He is a lucky guy to be breathing today.

Not sure if it had any factor on the Eddy current requirement, but it certainly made me a believer in recurrent inspections.

He was based with me at 7G0 just outside of Rochester. He was pretty meticulous about his maintenance since he owns an automobile repair shop. He was on a return trip from Elmira where he was taking glider lessons. Unfortunately the terrain was hilly where he set her down and both he and his passenger suffered spinal injuries.

He was indeed lucky...

[Andy95W]

I am curious if this is one of the supporting accidents initiating the eddy current inspections of the non B hubs. Did he keep it hangered in KELM or was it tied down there. With the finger lakes right there, Elmyra can be a harsh environment if outside I would think. He is a lucky guy to be breathing today.

The report says that 27 inches of one of the blades broke off. The non B hub eddy current inspection is strictly for the hub itself, for cracks, and does not check anything on the blades.

The report noted intergranular corrosion that led to the crack, so I wonder how the harsh environment affected that, as you said.

[Marauder]

The report says that 27 inches of one of the blades broke off. The non B hub eddy current inspection is strictly for the hub itself, for cracks, and does not check anything on the blades.

The report noted intergranular corrosion that led to the crack, so I wonder how the harsh environment affected that, as you said.

I don't remember where he bought the plane but he flew it from around 1993 until the accident date in 1999. I saw the plane up close a number of times and it was well maintained. And that was part of the issue, you can't necessarily see intergranular corrosion.

[N601RX]

I remember some props that were having intergranular corrosion that was starting under the label.  I don't remember if it was an AD or not, but seem to remember something about the manufacturer wanting everyone to remove the labels.

[Marauder]

I remember some props that were having intergranular corrosion that was starting under the label. I don't remember if it was an AD or not, but seem to remember something about the manufacturer wanting everyone to remove the labels.

Now that you mentioned it, I remembered that as well. I think it was limited to the Hartzell.

[Cody Stallings]

It was the Sensenich fixed pitch that had the corrosion issue under the decal.

Lots of good advise from you guys in this thread.

I want to add, a Part:91 Propeller is one of the most overlooked parts on an aircraft, but is the most stressed part.

Let's think of the propeller most of the vintage Mooneys was TCed with. Hartzell HC-C2YK-1/f7666A-2.

Great Propeller, built like Fort Knox.

One of the F7666A-2 blades weighs roughly 12-14lb Static. Same blade @2700rpms weighs in a little over a 9 Tons!!!!!! That's right TONS, in centrifugal weight.

That being said,once agin Hartzell builds props that are designed like Fort Knox, but from time to time Fort Knox needs to be maintained.