Those Tough Old Continentals!

[cessna170bdriver]

Still Running!

http://www.vansairforce.com/community/s ... hp?t=49722

[GAHorn]

I appreciate the intent of your post, Miles, but the pics actually tell us how fragile crankshafts are and why it's important to pay attention to such things as prop-strikes and which shops do our work. It appears that crank had been previously ground on the cheek of the broken, as well as the adjacent throw. If so, I'm pretty certain that is not an approved repair.

[hilltop170]

I have to go with Miles on this one, they are tough. The "beach marks" cover probably 80%+ of the fracture surface and indicate the gradual cyclic fatigue of the crank while it was still running, probably with no symptoms. That area represents the built-in factor of safety in the strength of the crank.

Then when it actually parted, it started running rough with the parted shaft still being held in position by the main bearings, but still running! The granulated fracture surface indicates the final catastrophic parting of the crankshaft due to overstress. I bet it ran for many hours from first crack propagation to failure, but the problem is you don't know it's broke till it comes apart.

So I also agree with George, if an illegal repair is thrown in, all bets are off and it's an accident waiting to happen. And any little ding or casting defect in a highly stressed area can start the crack that eventually causes the break. No telling what caused this break, but from it's initial start point, it was probably a machine tooling mark on the bearing journal.

The O-300-D in my 170 came off a wrecked C-172 that had a prop strike. It was torn down, inspected, overhauled, and installed on my plane in 1972. It ran for 1750 hours then it was removed for overhaul. The engine was running fine with no apparent problems. When the crank was NDT inspected, it was cracked 1/4 of the way around the front main bearing journal. Most likely due to the prop strike in 1968, 38 years before. Very similar to the O-200 crank in this post. The engine might have run another 2000 hours for all I know but may have failed on the next flight just as easy. So there's the nail-in-the-coffin for the argument for tear-down after prop strikes. It needs to be done. Correctly!

O-300-D crankshaft crack located with NDT inspection

[cessna170bdriver]

I appreciate the intent of your post, Miles, but the pics actually tell us how fragile crankshafts are and why it's important to pay attention to such things as prop-strikes and which shops do our work. It appears that crank had been previously ground on the cheek of the broken, as well as the adjacent throw. If so, I'm pretty certain that is not an approved repair.

Agreed, George. I was just commenting on the fact that with such severe damage that it was still running at all. You could never build a crankshaft to reliably endure a prop strike and expect it to be light enough to be practical in an aircraft engine. I'm guessing that's why any insurance policy I've ever read covers teardown and inpsection in the event of a prop strike - can save them much more $$$ later on. I hadn't looked closely enough to notice any repairs. I don't think it would ever cross my mind to "repair" a cracked crankshaft.

Miles

[GAHorn]

I drove a '51 Studebaker (Continental 6-cylinder flat-head) from Deming, NM to Austin, TX with an unknown "rattle/knock". The car mostly sat in my driveway but occasionally was used for parades and an occasional drive in the country. The "rattle/knock" was presumed to be a slapping piston, based upon a Work Order from a Los Angeles shop who had "expanded" a piston and reinstalled it.
The person I bought it from said the "rattle/knock" began shortly after that work, and I expected to overhaul the engine some day, hopefully before it threw a rod, but it ran so smoothly most of the time that I kept putting it off.
I sold it one day to a car collector, who called me back a year later to let me know the crank was actually broken at the front cylinder, just behind the #1 cylinder.

Yep....Continentals are tough.

[hilltop170]

I drove a '51 Studebaker (Continental 6-cylinder flat-head) from Deming, NM to Austin, TX with an unknown "rattle/knock". ........
I sold it one day to a car collector, who called me back a year later to let me know the crank was actually broken at the front cylinder, just behind the #1 cylinder.

Yep....Continentals are tough.

I bet it was a 7 main bearing engine also. If it was a 4 main engine it would have come apart.

[KS170A]

Several years ago, I departed Roswell, NM, for Odessa, TX, in a C-85 powered C-120. After takeoff, I could hear a sound that resembled metal hitting metal, but couldn't place it. Finally, near Andrews, TX, there was a tremendous rattling. I ended up landing on a road, calling some friends, and trailering the airplane back to KODO. At first, we found the generator drive gear had sheared off at the bearing and fell into the accessory case (hence the rattling). When I removed the cylinders for complete engine overhaul, I found the source of the metallic sound - a two-piece crankshaft, very similar to the one pictured! I suspect it would have flown more had the generator gear not sheared. The source of that crank's fracture, I believe, was an improper grinding at the previous overhaul (about 200 hours prior to my event).

[blueldr]

George,
What in the world were you doing in Demming, NM, in a Studebaker? I suppose that Demming has changed a lot since I was there in 1944, but from my experience I wonder why anyone would go there on purpose. I was stationed at Demming Army Air Field flying "Light Bombers". (AT11s). I always felt that if the almighty was ever going to give the earth an enema, the insertion would be made in down town Demming.

[GAHorn]

George,
What in the world were you doing in Demming, NM, in a Studebaker? I suppose that Demming has changed a lot since I was there in 1944, but from my experience I wonder why anyone would go there on purpose. I was stationed at Demming Army Air Field flying "Light Bombers". (AT11s). I always felt that if the almighty was ever going to give the earth an enema, the insertion would be made in down town Demming.

The enema would be administered in Killeen, TX!

I was in Demming to TRADE my 1947 Aeronca Chief for the Stude, with a pilot out there named Kip Monet. He and his granddaughter drove it from LAX to Demming, and my brother and I flew the Chief from AUS to Demming. We made the trade at the airport.

[170C]

Come on George, don't tell us you traded a good flying airplane for a Studebaker Surely not And after living for 6 months in Monahans, TX with Gulf Oil Corp I thought THAT was were the enema would have been inserted Super nice folks (typical of west Texans & eastern New Mexicans) but not a place I would want to have to live in again

[blueldr]

Holey Cow! An Airplane for a Studie? Were they still building Studies then?

Apparently there was a time when a much younger Geoge seems to have been less than the swiftest arrow in the quiver.

[Bruce Fenstermacher]

Holey Cow! An Airplane for a Studie? Were they still building Studies then?

Apparently there was a time when a much younger Geoge seems to have been less than the swiftest arrow in the quiver.

BL BL, "the swiftest arrow in the quiver"?

Implying that George at one time was less would indicate that he may equal that metaphor today. I'm just having a hard enough time imagining George moving as an arrow would, but the the swiftest.

I could more easily picture George at one time not being the sharpest tack or pencil in a box.

[hilltop170]

So George,
Not knowing Studebakers or Chiefs very well, who got the better deal?

[voorheesh]

Kip Monet is a member of the Bakersfield, CA QB hangar and lives near Frazier Park. Great guy. I hear he has a unique flight museum at his house and had an interesting career as a pilot. I haven't seen him in a couple of years but hope he is doing well.

[GAHorn]

Kip Monet is a member of the Bakersfield, CA QB hangar and lives near Frazier Park. Great guy. I hear he has a unique flight museum at his house and had an interesting career as a pilot. I haven't seen him in a couple of years but hope he is doing well.

I'm glad to hear about Kip!

For the rest of you guys, ...as Paul Wood might say..."Don't get your drawers in a wad."

The truth of the matter would make a great read in the 170 News. Maybe I should write up the story. I've even got lots of pictures of the journey and the swap.

Kip was a demo-pilot for AirReasearch and brought a Hawker to AUS to demo the 731-Fan conversion to me. (I was chief pilot....no pun intended....for a bank with a Viper-powered Hawker.) As we drove down the flight-line on the way to lunch, Kip saw my Aeronca Chief sitting on the ramp and went ballistic and wanted to stop and look at it. He didn't know it was mine.
Kip looked it over and exclaimed, "I've always wanted a Chief! This is a nice one! Do you know who owns it? Do you think he'd sell it?"
I had just put a new engine and custom interior in it the previous year and it had less than 50 hours SMOH, due to the loss of oil pressure in it's previous engine. (Some of you might recall the story I told about my dead-stick landing due to an overtightened oil-temperature probe which let loose all the oil following an oil change.)
I had only flown the Chief 10 hours in the entire previous year,....one hour taking it for annual inspection...one hour bringing it back home....1/2-hour local joy-ride....and the rest of the 7-1/2 hours loaned out to a guy I thought was a friend (until I discovered he'd susequently bad-mouthed me at a job-interview.) It was 1986, the economy was like it is right now, and the cute little airplane was costing me monthly hangar at AUS Mueller and I was about to go thru a divorce, and the airplane began to look like an Albatross more and more each day.
So when Kip began to froth at the mouth for that Chief I told him, "Yeah, I know the owner, and he'd probably like to sell it, but he's got more money in it than it's worth, so I doubt you would pay his price!"
Kip responded, "Well, maybe he'd like to trade something for it. Who is he? What are his hobbies?"
I grinned and told him, "I own that airplane and ...(making up a wild-request on the spot)...unless you've got a 1951 bullet-nosed Studebaker, I don't think we can do business."
Kip became stone-faced. He squinted into my eyes as if looking for something....and responded, "Who told you about my Studebaker?"

No kidding. That's exactly how it happened.

The only caveat was that we each agreed that the swap was reversible anytime either one of us changed our minds. He called me several times over the next year to see if I wanted him to put a new engine in the Studebaker. I've got nothing but good feelings about Kip, and I wouldn't go-back on a handshake with another QB for anything in the world.