Lifting aircraft by the crankshaft lifting eye

[Corbinace]

Greetings,

I have a question about use of the lifting eye that screws onto the end of the crank of the 985.

Is it allowable under any circomstances to lift the entire weight of the aircraft (less tailwheel wieght) by using the lifting eye? Rough guestimate 2000 pounds.

I am one of a gaggle that is talking about transporting an aircraft in an enclosed trailer and it has been suggested that we pick the forward portion of the fusalage and run it into the trailer using the crank as the pick point.

I am pretty ignorant as to the inner supports of this crankshaft, but I just cannot immagine this being a good practice. I thought that this lifting eye was intended to be used in the "crank vertical" plane, with the thrusts supporting the load not the way we are proposing.



Thanks for your assistance, Tim.

[FLYBOYJ]

Greetings,

I have a question about use of the lifting eye that screws onto the end of the crank of the 985.

Is it allowable under any circomstances to lift the entire weight of the aircraft (less tailwheel wieght) by using the lifting eye? Rough guestimate 2000 pounds.

I am one of a gaggle that is talking about transporting an aircraft in an enclosed trailer and it has been suggested that we pick the forward portion of the fusalage and run it into the trailer using the crank as the pick point.

I am pretty ignorant as to the inner supports of this crankshaft, but I just cannot immagine this being a good practice. I thought that this lifting eye was intended to be used in the "crank vertical" plane, with the thrusts supporting the load not the way we are proposing.

Thanks for your assistance, Tim.

Do you have the maintenance manuals for the aircraft you are working on? If so what do they say for jacking and moving? If you put the wrong loads on the crank you could possibly induce seal failure at the FGB.

[robwkamm]

i would say no. i think your putting a shear load on the crank end. its not designed that way. you may bend the crank a little and your done. i have seen some engine stands that hoold the engine with the crank , but its only the crank case/power section its holding up. if you think of it this way , your hanging a 20+foot bar on the end of a 2 5/8" shaft. something going to give, it a leverage thing.

[vintage radials]

If you remove the aircraft from the engine, the lifting eye works great. Trying to lift the A/C will also max out the mounts along with a few other areas of the front of the a/c. however if the A/C is rated at 5 or 6 G's negative you should be ok as the structures of the A/C will handle the load but you are still overloading the prop shaft. Even at 6 G's the prop is never going to equal the weight of the A/C.

[Corbinace]

Thank you one and all,

I spoke to a couple of other round engine guys after I posted this query and they both had the same answers that I saw from you when I got home.

The list of bad outcomes included the possibility of damage to the bearings, prop shaft, and motormounts.

While one person conceded the possibility of a single gentle pick straight up and straight down being OK in a pinch, both were dead set against carrying the front end of the ship around by its nose due to the shock loading.

I can now make an educated plea to find another way to do our lifting.

Thank you, Tim.

[engguy]

What is the aircraft? I am not familiar with the 985 so is the prop shaft integral with the crankshaft? Like Rob says there are old engine overhaul stands that support the full weight of the engine assembly from the propshaft. And these engines were the biggest radials too. Like R-4360's, R-3350's etc the engines weight is in excess of 3000 plus pounds, and remember the engine is overhanging and puttting an incredible moment on that shaft. The propshaft is probably the strongest thing on the engine there is that will bear weight. In tension it will more than carry the weight of the whole aircraft assembly. If the plane was say a supercorsair with an R-4360 I don't think there would be a problem trying to lift half that planes weight on the propshaft, and I would tend to think rather than using the normal screw on lifting eye, that cradeling the shaft with a large fabric strap would be better to lift with as it would distribute the weight better on the shaft.
It is too bad that engineering information like that isn't available from the manufacture, in the old days a simple phone call would be all it would take. Now they probably don't have anyone there that even knows it is one of theiir products, let alone know the answer.

[Corbinace]

What is the aircraft? I am not familiar with the 985 so is the prop shaft integral with the crankshaft? Like Rob says there are old engine overhaul stands that support the full weight of the engine assembly from the propshaft. And these engines were the biggest radials too. Like R-4360's, R-3350's etc the engines weight is in excess of 3000 plus pounds, and remember the engine is overhanging and puttting an incredible moment on that shaft. The propshaft is probably the strongest thing on the engine there is that will bear weight. In tension it will more than carry the weight of the whole aircraft assembly. If the plane was say a supercorsair with an R-4360 I don't think there would be a problem trying to lift half that planes weight on the propshaft, and I would tend to think rather than using the normal screw on lifting eye, that cradeling the shaft with a large fabric strap would be better to lift with as it would distribute the weight better on the shaft.
It is too bad that engineering information like that isn't available from the manufacture, in the old days a simple phone call would be all it would take. Now they probably don't have anyone there that even knows it is one of theiir products, let alone know the answer.

I am ignorant of the internal design of the P&W R-985. It is mounted on a replica 1931 Bellanca Skyrocket J-300, so the ship is not real heavy with the flying surfaces and wheels off of it. I called Kenmore Air who built the engine for us and they said absolutely not to lift it in the manner described as it could damage the bearings on the shaft. One thing that is different from the engine stand scenario is that while the ship is being moved by the forklift there will be some shock loads as the tires move over irregularities on the ground. Your idea of putting the strap in closer to the root of the shaft has merit, as it would reduce the moment considerably.

Thanks for the input Engguy

[engguy]

I guess they should know what they are talkin about on those engines.

On a 4360 hangin on a wing with the prop feathered, and the plane pulling 3 or more G's, and turbulence etc. That propshafts gona get some nasty loads on it. Since the prop is somewhere in the 1,100 lb or more area. And then theres the load on the air frame with that engine and prop hangin out there off the wing around 12 feet or so. Then there is gyroscopic loads during aerobatic manuvers, especially in war times.
There is quite some loading on those shafts at times.

[Buster01]

A few more words on this:

Most radials use a reduction gear in the nose case so the prop shaft is turning at a different speed than the crankshaft. The entire load from the prop (thrust, gyroscopic forces, etc.) is transferred to the crankcase via the nose case and on to the airframe via the engine mount. When a prop strikes anything, the nose case fractures, and the prop usually breaks free from the engine.

Lifting the airframe via the prop shaft will almost certainly break the nose case, and that is a very bad thing.

Regards, Terry

[GregP]

We restore and maintain WWII aircraft at the Planes of Fame all the time. We never put all the weight of the aircraft on the crankshaft. If the aircraft is complete, we use the jack points.

If the aircraft is not complete, we fabricate a cradle and lift at the engine mount, the rear jackpoint, and at least one if not two more points along the fuselage. By way of example, we have a long-term restoration going on right now in Fighter Rebuilders (within a hangar at the Planes of Fame) of a Grumman F7F Tigercat. They fabricated a cradle for the fuselage so they could keep the fuselage straight while removing a lot of panels ... eventually all panels, and replace as necesary.

If you lift on the engine and transport that way, you will have to tear the engine down to its component parts and have the crankshaft checked for straightness and magnafluxed before you'd want to fly it. That can get expensive. Weld up a cradle and transport it the right way. Attach at the engine mounts, any jack points, and several intermediate places to bolt into the structure. Good luck! It ain't cheap, but it also doesn't damage the aircrft or engine.

We just transported a Hawker Sea Fury (September Fury) from Reno back to Chino that way, and the aircraft was jacked up about 35° on its side in a cradle, like an old hydroplane race boat used to be carried, so it would be narrow enough to roll down the road with the wing center section still attached. it is now back together and getting ready for engine work. It ate an R-3350 at Reno on Moday before the Galloping Ghost crash on Friday and was down after that time.

[engguy]

I'm not saying to lift with the prop shaft.
On a C-97 with an approximatly 1200 to 1500 lb prop assembly hanging on the prop shaft. With the engine off an in a 4 g pull up, that would be over 5000 lbs.
Now if that engine in hanging on a whiting stand, you have close to 3500 lbs bending that shaft and straining on the bearings. I would really like to know what the shaft load would be in rapid manuver at rated rpm in an unloaded condition like a partial dive pull up and turn. The gyroscopic loads must be pretty significant.
In tension that shaft will take what ever thrust the prop creates, any ideas of what that is? So how much does a plane like furious weigh? Just the airframe?

[GregP]

Engguy,

A basic Sea Fury weights in about 9,250 pounds empty and about 12,500 pounds loaded. A Bristol Centaurus weighs in anout 2,695 pounds dry weight.

It will handle 8 g's, but that is 8 g's of normal acceleration, 90° from the direction of the crankshaft, evenly distributied in the main bearings, not that weight hanging on the propeller end. The bearings won't come CLOSE to handling that weight without major damage. If you tried to lift the entire Sea Fury vertically by the propeller huib, you'd very probably pull the hub out through the back end of the Centaurus and be left with a crankshaft hanging on the end of the chain. Crankshafts of ANY type are designed for their tasks, not to be used as crane attachment points.

[engguy]

In a strait up vertical climb all the weight would be on that shaft. And I'm sure it would take all the weight as good as a helicopters bearings and shaft would.
That prop shaft and bearing assembly is likely the strongest part of any aircraft engine. Crankshaft ????? doesn't a centarus go through a reduction gear set just like any of the other large radial engines?
The old timers that designed those engines would have made sure those shafts and bearings could handle many times the normal loading, thats mechanical engineering. And 9,250 lbs is nothing when you are talking materials that can take into the 200,000 pounds per square inch range or more. Gosh your looking at 4 tons plus of tensil load on a little conneting rod in an F1 engine. I'm sure those bearings and prop shaft could take 4 times what that little con rod can, easy.

[GregP]

Go ahead, Enguy, and lift up YOUR warbird by the engine crankshaft. None of the more than 20+ warbird owners I know would do that but, by all means, go ahead.

Then start it up and go fly it. I wait for the news article.

[engguy]

I said I wasn't condoning it, though it would be interesting to hear from some old timers from the big one WWII on this one. I bet a few warbirds been lifted that way back then. Smokey Yunick would be a good one to ask but hes gone.