First propeller bolt pulled and not looking good

[Strutwipe]

So my new to me Tomahawk went into annual the beginning of April. I had a high oil pressure indication that drove me nuts for a while. It seems the pervious owner changed out the OPRV spring to the wrong part number. Since the prop is 1800 hours over TBO, I figured it would be a good idea to get it OH. When I pulled the first bolt my heart, and wallet, sank. All of the prop mounting holes have pitting in them. Has anyone ever seen a prop survive OH with pitting inside the mounting holes?

 

[Timbeck2]

Someone who knows more will give a more definitive answer but based on that one picture, I don’t think it’s as big a deal as you think it might be.

Do you drive a red truck? If so you were in your hangar when I got there yesterday afternoon. Look for a white F-150 in the parking lot at our hangar behind yours.

 

[Bell206]

Has anyone ever seen a prop survive OH with pitting inside the mounting holes?

Yes. What model prop? And may want to research a bit more on prop repair vs overhaul vs replace before simply sending it out for O/H just because or past TBO. Sometimes for certain props it can be more advantageous to pursue one path over another.

 

[Strutwipe]

Someone who knows more will give a more definitive answer but based on that one picture, I don’t think it’s as big a deal as you think it might be.

Do you drive a red truck? If so you were in your hangar when I got there yesterday afternoon. Look for a white F-150 in the parking lot at our hangar behind yours.

Actual, I'm over in the shade tiedown area, just look for the Tomahawk tail sticking out. I've got a silver Frontier. Hanger space is quite the premium in southerner AZ I see.

I took the prop over to Warren to have a look over/OH. It has been "dressed" a number of times so that may be an issue. Ed, with the 170, explained to me that Warren failed his prop due to bolt hole corrosion. I was just wondering if anyone has been down this road. One thing is for sure, I prefer telling someone else they need major work done

 

[Strutwipe]

Yes. What model prop? And may want to research a bit more on prop repair vs overhaul vs replace before simply sending it out for O/H just because or past TBO. Sometimes for certain props it can be more advantageous to pursue one path over another.

72CK-0-56 SENSENICH PROPELLER

 

[Bell206]

72CK-0-56 SENSENICH PROPELLER

Give Sensenich a call. They used to have a bulletin to rework the mount holes but I don't recall for what purpose. They may also have some additional info. Be sure to tell them your an A&P. Just keep your options open on what to do with that prop cost wise.

 

[Dan Thomas]

Bore pitting is a concern. In Canada the regulations have this to say about fixed-pitch props:


CAR 625 Appendix C
6. Fixed Pitch and Ground Adjustable Propellers

• (b) At intervals of not more than 5 years, the propeller shall be removed from the aircraft and inspected for corrosion or other defects over its entire surface, including the hub faces and the mounting hole bores. While the propeller is removed, it shall also be checked for correct dimensions. However, if defects which require repairs beyond those recommended as field repairs by the propeller manufacturer are found, the propeller shall be repaired by an organization approved for the overhaul of propellers.

Steel bolts in aluminum propellers cause corrosion when moisture gets in there. Corrosion pitting can cause cracking and catastrophic prop failure. It would be rare. How much pitting is OK? Don't know. The prop guys have prop manufacturer's manuals to guide them, so that's where the prop goes.

Our five-year inspection mandate tends to catch that stuff early, before it's too late to save it.

 

[NordicDave]

General comment NOT directed at OP.

Amazes me how little care some pilots give props. Startling how many years in service some props have gone without a prop shop IRAN or overhaul, especially fixed pitch since there is no “Red mist” to compel an inspection.

Using the OP’s picture as a talking point... If rust can be seen in the bolt head area and rust staining on the prop face; good opportunity to be curious. As rust just initiates, is a good time to have your A&P pull the bolts and look.

 

[Strutwipe]

General comment NOT directed at OP.

Amazes me how little care some pilots give props. Startling how many years in service some props have gone without a prop shop IRAN or overhaul, especially fixed pitch since there is no “Red mist” to compel an inspection.

Using the OP’s picture as a talking point... If rust can be seen in the bolt head area and rust staining on the prop face; good opportunity to be curious. As rust just initiates, is a good time to have your A&P pull the bolts and look.

I am in agreement with you. I bought this aircraft two months ago and slowly been correcting past sins and discrepancies as they show up. When I took the lower cowling off, I was sadden by the lack of attention to detail by the pervious A&P/IA owner.

 

[kyleb]

I am in agreement with you. I bought this aircraft two months ago and slowly been correcting past sins and discrepancies as they show up. When I took the lower cowling off, I was sadden by the lack of attention to detail by the pervious A&P/IA owner.

Tomahawks are now 40 year old airplanes that have never lived at the high end of the value chain. They are great airplanes, but many airplane owners who seek out bargain airplanes also seek out bargain maintenance, so there are probably a lot of 'em out there that are under-maintained. Glad you're taking care of this one. I had a tomahawk as my first airplane.

 

[Strutwipe]

Tomahawks are now 40 year old airplanes that have never lived at the high end of the value chain. They are great airplanes, but many airplane owners who seek out bargain airplanes also seek out bargain maintenance, so there are probably a lot of 'em out there that are under-maintained. Glad you're taking care of this one. I had a tomahawk as my first airplane.

Some of these discrepancy make me shake my head. Simple stuff like safety wire neutral or backwards. A screw installed to stop a crack. Tension spring missing from baffling. The list goes on.

For this annual, all the fuel and oil flex lines are being replace. Gascolator upgraded to Steve's Aircraft version. Either new SureFlys or OH of the Slicks. OH the prop, if I'm lucky, or new. New baffle material. Replace all external rusty hardware. And of course use the $20/gram valve lube on the fuel selector. Check rocker push rods and perform valve clearance. The one upgrade I would like to do but having an issue finding is a four point harness. By the time I get done this will be a 50K plane worth 25K

 

[GRG55]

All signs of a prior owner that fashioned himself a qualified airplane mechanic but wasn't. Not uncommon, unfortunately.

You'll have the satisfaction of knowing the plane is sound, reliable and safe to fly when you are done.

 

[Doc Holliday]

Tomahawks are now 40 year old airplanes that have never lived at the high end of the value chain. They are great airplanes, but many airplane owners who seek out bargain airplanes also seek out bargain maintenance, so there are probably a lot of 'em out there that are under-maintained. Glad you're taking care of this one. I had a tomahawk as my first airplane.

This problem is not unique to Tomahawks or other small trainers. I've seen a fair share of higher end airplanes (Bonanza, 210's, etc) that suffer the same fate as the owner wants such a plane but doesn't want his hobby money being wasted on maintenance.

 

[bnt83]

This problem is not unique to Tomahawks or other small trainers. I've seen a fair share of higher end airplanes (Bonanza, 210's, etc) that suffer the same fate as the owner wants such a plane but doesn't want his hobby money being wasted on maintenance.

For sure. Just bought a set of fine wires for my O320, $700 in spark plugs... That's a lot of beer money. Good thing I don't drink. With any luck I'll live long enough to wear them out.

A lot of folks that buy these aircraft have never owned a 40 year old car with a mechanical ignition and a carb, or tried to keep one on the road and dependable.

 

[Bell206]

and an AN4 bolt standing in for an NAS464P4 bolt, as I’m currently experiencing with sorting out my seat belts.

FYI: most aircraft came standard with AN bolts in the seatbelts. A number of years ago hardware mfr’rs quit producing various spec hardware like AN, offering only NAS, MS, etc. The aircraft OEMs updated their IPCs to reflect this change in the supply and it now shows NAS bolts for seatbelts where AN bolts used to be listed. If you look in an older revision IPC you will see the AN hdw listed which are still acceptable for most S/N aircraft.

 

[Strutwipe]

Not to get off topic but I am curious about a certain thought process I'm having. While I await the fate of the propeller, I have been stripping paint on some panels to clean up surface corrosion. As I'm doing this, I have the overwhelming need to save another Tomahawk from Texas Salvage Yard. I'm comparing this to a women that just gave birth, all the pain and agony, but now wants another baby.

 

[Bell206]

he first 172 that came with a shoulder harness they secured it with an NAS464P4 bolt.

The AN to NAS hardware swap started over 30 years ago so maybe Cessna had converted already. It affected the entire industry. Perhaps they determined for the shoulder harness they needed the 464s. I don't know. But the 3 IPCs I just looked at all show AN4 for the lap belts in 172s and 182s. AN is still a good bolt though, considering they're still called out to secure the wings, tail feathers etc.

 

[Dan Thomas]

The AN to NAS hardware swap started over 30 years ago so maybe Cessna had converted already. It affected the entire industry. Perhaps they determined for the shoulder harness they needed the 464s. I don't know. But the 3 IPCs I just looked at all show AN4 for the lap belts in 172s and 182s. AN is still a good bolt though, considering they're still called out to secure the wings, tail feathers etc.

They called for AN4s in the lap belts, but for the shoulder harness attach it was the NAS464. It's an overhung load, not a pure tensile or shear load. Like others, I have often found AN4s there while the IPC calls for the NAS bolts.

 

[kgruber]

You might call the FBO Avion at the Bremerton National Airport (KPWT). There are four Tomahawks just rotting away there. They moved them way out to the sticks. There might be some good parts for you.

 

[schmookeeg]

General comment NOT directed at OP.

Amazes me how little care some pilots give props. Startling how many years in service some props have gone without a prop shop IRAN or overhaul, especially fixed pitch since there is no “Red mist” to compel an inspection.

Using the OP’s picture as a talking point... If rust can be seen in the bolt head area and rust staining on the prop face; good opportunity to be curious. As rust just initiates, is a good time to have your A&P pull the bolts and look.

I'm sort of curious about this. Fixed-pitch props are slabs of metal. What's to go wrong that won't be noticed on a preflight?

Also to your point, though, constant-speed props terrify me. If I have a nightmare about flying, it will be a blade being chucked and the rest of the FWF following it, leaving me to pick a crater to tumble self and wreckage into. I have always IRAN'ed new-to-me CS props. I'm still highly suspicious of them.

 

[NordicDave]

I'm sort of curious about this. Fixed-pitch props are slabs of metal. What's to go wrong that won't be noticed on a preflight?

On the fixed pitch, the prescribed pitch angle flattens overtime and needs to be re-twisted to specifications. Props having a very long service life, not uncommon to find them dressed below service limit dimensions. I’ve also seen them with stress fractures and other issues revealed with eddy current inspections.

Most prop shops will inspect for no charge, with a fix pitch overhaul typically $1500-$2200. Prop comes back looking like brand new. Very common for pick up and drop off charges included in the price for a shop in the region. It would be easy to speculate an aircraft owner would recoup that in fuel savings overtime with more efficient set of blades.

I suspect some who have a prop service in many years without overhaul, avoid it due to the risk of being told it’s below service limits and requiring to put out $5500-$6500 for something new or newer.

 

[arnoha]

I'm sort of curious about this. Fixed-pitch props are slabs of metal. What's to go wrong that won't be noticed on a preflight?

Agree with @NordicDave . I recently had my 172's prop overhauled. It was due to corrosion on the rear mounting face. There was no way I was ever going to see that. The only reason we saw it at all was due to a renter of my aircraft scratching the prop on something (and I still don't have the whole story). That necessitated the inspection, which resulted in discovering the unrelated corrosion. And yeah, it was $2000 + R&R. The prop did, indeed, come back looking shiny and new.

 

[Strutwipe]

Well, I just got off the phone with the prop shop. Anyone want to buy a wall hanger?

 

[Dan Thomas]

Well, I just got off the phone with the prop shop. Anyone want to buy a wall hanger?

For $850 in postage?

What was the deal-breaker? Corrosion or under limits? Both, maybe?

 

[Strutwipe]

For $850 in postage?

What was the deal-breaker? Corrosion or under limits? Both, maybe?

Both, too much dressing and corrosion in all of the bores.

 

[455 Bravo Uniform]

Not to get off topic but I am curious about a certain thought process I'm having. While I await the fate of the propeller, I have been stripping paint on some panels to clean up surface corrosion. As I'm doing this, I have the overwhelming need to save another Tomahawk from Texas Salvage Yard. I'm comparing this to a women that just gave birth, all the pain and agony, but now wants another baby.

Perhaps you need a CT scan to make sure nothing unusual is starting to grow in the cantaloupe.

Just a few days ago I started thinking of swapping some equity in my 182 for a well worn but taken care of 182 to restore. I may have a brain issue.