Aircraft Engine Failure.
- Thread starter ChipBeck
- Start date
Indy GT
Yea, I got one...too
Chip, glad you are running again!
If you would, could you post up a picture of the failed section of the crankshaft. And maybe specifically the fracture surface.
Likely a fatigue failure and it would be interesting to see if a crack grew out of a geometric stress concentration feature.
As many technical experts contribute to our forum it might be of intellectual interest for a few.
Hope your shakedown flight goes smoothly.
If you would, could you post up a picture of the failed section of the crankshaft. And maybe specifically the fracture surface.
Likely a fatigue failure and it would be interesting to see if a crack grew out of a geometric stress concentration feature.
As many technical experts contribute to our forum it might be of intellectual interest for a few.
Hope your shakedown flight goes smoothly.
33Bravo
GT Owner
fjpikul
GT Owner
Kendall,
For a short while Lycoming made a 720 c.i. 8-cylinder motor but they were never certified for aerobatics. The 540 c.i. 6-cylinder in my plane is the biggest engine they make today and the Glasair III is about the smallest aircraft you can stuff it into. It is considered to be the Shelby Cobra of light aircraft and it's a handful for inexperienced pilots. Most insurance companies will not cover them because of high accident rates. Once you get use to the Learjet landing and traffic pattern speeds they are a joy to fly and they are tough to break in flight as it will handle 9 G's positive and 6 G's negative.
Chip
Indy,
I'll try to find something better than my I-phone camera to get some good shots. I see in one of my posts I said the crankshaft failed but I didn't mean it broke in half. Just that it failed inspection and was red tagged by the shop during the tear down and post mortem. I have a pretty good camera and I'll dig it out and try to take some good photos. I have a question for you Bill. Why would a tri-metal bearing be better than a bi-metal bearing? I wasn't aware that even two different types of steel were used in bearings let alone three. I don't understand that and you can probably explain it.
Chip
I'll try to find something better than my I-phone camera to get some good shots. I see in one of my posts I said the crankshaft failed but I didn't mean it broke in half. Just that it failed inspection and was red tagged by the shop during the tear down and post mortem. I have a pretty good camera and I'll dig it out and try to take some good photos. I have a question for you Bill. Why would a tri-metal bearing be better than a bi-metal bearing? I wasn't aware that even two different types of steel were used in bearings let alone three. I don't understand that and you can probably explain it.
Chip
Last edited:
Wwabbit
GT Owner
598
GT Owner
This is a post I've been waiting for. I'm so happy for you. Best wishes for you and your test flight. How is Charlie feeling about the whole event?
Steve
Steve
Indy GT
Yea, I got one...too
Frank, as I was making my post(s) there was a “server problem” and it would not show me if my post had been processed and added to the thread. I notified Dave and he must have edited out the duplicate (or triplicate) posts. Thanks DBK.
Thanks Chip, let me try, with appropriate acknowledgment of reference material from Obert’s book on Internal Combustion Engines and Air Pollution and Shigley’s book on Mechanical Engineering Design:
Typical engine bearings must be designed to possess a number of design attributes:
1. Friction- It should have low friction coefficients in relation to the shaft materials.
2. Scoring- Is should not abrade or seize the shaft material and, preferably, it should be able to operate with unhardened journals.
3. Strength and Fatigue- It should retain its strength throughout the temperature range of service without flow, cracking, or fatigue, and it should be able to withstand shock loads.
4. Embeddability- It should be able to absorb abrasive particles that would otherwise score the shaft.
5. Corrosion- It should not be attacked by either the oil or oil contaminants, nor should it catalyze such attacks upon neighboring material.
6. Plasticity- It should be able to conform to the shaft, especially in the break-in period.
7. Bondability- It should adhere or bond with its backing material.
8. Thermal Conductivity- It should be a good conductor of heat.
9. Adaptability- It should be readily machined or cast, and be inexpensive to produce.
Modern day Internal Combustion (IC) engines typically use bearings constructed with multiple layers of differing materials allowing tailoring of the bearing to its specific service application and optimization of the above listed design parameters. Present day bearing construction uses steel or bronze inserts which fit into engine block/rod-end support structures, although steel backed bearings have largely replaced the bronze base since the layering materials bond better with steel. Bearing inserts can be produced within close tolerances, and therefore bearings can be replaced without additional fitting or surface scraping to achieve desired build clearances.
The steel insert is usually “tinned” with a bonding agent and the bearing layer materials applied to the steel backing by either casting, sintering or pressure bonding. “Babbitt” or white metal bearings are a general term that refers to either a tin or lead-base alloy of various metals. Babbitt bearings are now almost exclusively used in modern gas/diesel engines. The tin base is usually preferred for heavy duty applications as the tin (and lead) is soft, with a low melting point that enables the alloy to flow and relieve misalignment, while the additions of copper and antimony to form an alloy provide the necessary strength. Babbitt is popular because partial failure allows plastic flow and the bearing can still function; and with complete failure, little or no damage may result to the shaft. Obviously with a loss of lubrication or outright fatigue failure of the bearing layers (resulting in increased running clearances and elevated impact shock loads) the crankshaft or rod-end journal can be severely damaged. Moreover, the tin-base and most lead-base alloys resist corrosion. Lead-base babbitts have not been as popular as the tin-base, because lead is susceptible to attack by acids in the oil.
Chip, all this to say the bearing has a singular steel backing with multiple layers bonded to this backing which are the actual “wear” materials. Depending on the bearing design and manufacture preference there can be two, three or a number of additional layers applied to the steel backing which is what you are questioning.
Hope this helps give you a better appreciation of your engine internals……:wink
PL510*Jeff
Well-known member
While the story below has absolutely nothing to do with aircraft engines and bearing composition, true or not, makes sense out of engineering solutions to a very serious problem. Enjoy Mr. Bill
. Value Engineering
This one is well worth the time to read it....... You don't have to be an engineer to appreciate this story.
A toothpaste factory had a problem. They sometimes shipped empty boxes without the tube inside. This challenged their perceived quality with the buyers and distributors. Understanding how important the relationship with them was, the CEO of the company assembled his top people. They decided to hire an external engineering company to solve their empty boxes problem. The project followed the usual process: budget and project sponsor allocated, RFP, and third-parties selected. Six months (and $8 million) later they had a fantastic solution - on time, on budget, and high quality. Everyone in the project was pleased.
They solved the problem by using a high-tech precision scale that would sound a bell and flash lights whenever a toothpaste box weighed less than it should. The line would stop; someone would walk over; remove the defective box; toss it into a bin; and then press another button to re-start the line. As a result of the new package monitoring process, no empty boxes were being shipped out of the factory.
With no more customer complaints, the CEO felt the $8 million was well spent. He then reviewed the line statistics report and discovered the number of empty boxes picked up by the scale in the first week was consistent with projections. However, in the next three weeks, there were zero empty boxes! The estimated rate should have been at least a dozen boxes a day. He had the engineers check the equipment, they verified the report as accurate.
Puzzled, the CEO traveled down to the factory; viewed the part of the line where the precision scale was installed; and observed that just ahead of the new $8 million dollar solution.... sat a $20 desk fan blowing the empty boxes off the belt and into a bin. He asked the line supervisor what that was about.
"Oh, that," the supervisor replied, "Bert, the kid from maintenance, put it there because he was tired of walking over every time the bell rang."
. Value Engineering
This one is well worth the time to read it....... You don't have to be an engineer to appreciate this story.
A toothpaste factory had a problem. They sometimes shipped empty boxes without the tube inside. This challenged their perceived quality with the buyers and distributors. Understanding how important the relationship with them was, the CEO of the company assembled his top people. They decided to hire an external engineering company to solve their empty boxes problem. The project followed the usual process: budget and project sponsor allocated, RFP, and third-parties selected. Six months (and $8 million) later they had a fantastic solution - on time, on budget, and high quality. Everyone in the project was pleased.
They solved the problem by using a high-tech precision scale that would sound a bell and flash lights whenever a toothpaste box weighed less than it should. The line would stop; someone would walk over; remove the defective box; toss it into a bin; and then press another button to re-start the line. As a result of the new package monitoring process, no empty boxes were being shipped out of the factory.
With no more customer complaints, the CEO felt the $8 million was well spent. He then reviewed the line statistics report and discovered the number of empty boxes picked up by the scale in the first week was consistent with projections. However, in the next three weeks, there were zero empty boxes! The estimated rate should have been at least a dozen boxes a day. He had the engineers check the equipment, they verified the report as accurate.
Puzzled, the CEO traveled down to the factory; viewed the part of the line where the precision scale was installed; and observed that just ahead of the new $8 million dollar solution.... sat a $20 desk fan blowing the empty boxes off the belt and into a bin. He asked the line supervisor what that was about.
"Oh, that," the supervisor replied, "Bert, the kid from maintenance, put it there because he was tired of walking over every time the bell rang."
Cobrar
GT Owner
CH53Driver
Shelby GT500 owner
Glad you and you're son were able to walk away in one piece Chip. Very fortunate indeed. Had enough close calls of my own and more than a few of my friends are no longer around. Many people often ask me why I don't fly as a job anymore and it's stories like yours I wish they could read. Maybe someday I'll step back into the cockpit but for now I'm enjoying being earthbound like we were designed to be. I do miss it at times though. Waldo's a lucky man. Not all of us get that "get out of jail free" card with the pull of a handle (I have a buddy who's a former Harrier pilot and he quit flying after having an ejection experience at night at a thousand feet AGL while the aircraft was departing controlled flight). Two statements from my flying helicopter days come back to mind: "Real men ride it in" and "The CH-53E was designed to keep the pilot's mind, hands and feet occupied while he plummets to his death".