You're flying along and your propeller has a structural failure

JCranford said:
Thats what I hate about sitting near the front of the Otter when I skydive. Im sitting RIGHT by that spinning prop thinking about a blade coming off...
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Riding up front in an Aerostar is just as sobering....:yikes:
 
I have a BRS for this possibility... :yes:

...but the front bridles attach to the engine mount. :no:

:sad:
 
jbDC9 said:
ethinks I got really, really lucky to walk away from that one...
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When you start flying, you get two buckets. One says "luck" and is full of coins. The other says "experience" and it's empty. Every time something happens where you were lucky, you take a coin (or 10) out of the luck bucket and put it in the experience bucket.

The hope is you get enough experience that you don't run out of luck coins.
 
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This is my great-grandfather's lost-prop story. The article says "part of the engine" fell off after the propeller broke but as the story was told to me, the prop split in the middle and fell off its mount, I don't think anything else fell off.
 
A follow up question for all this, if this WAS to happen. Would insurance cover the repairs to the engine/prop or are you out of pocket 10-15K for a teardown/prop replacement, etc...
 
I wonder if these events are more common with homebuilts, racers, and other experimentals.
 
rachelk.tailwinds said:
This is my great-grandfather's lost-prop story. The article says "part of the engine" fell off after the propeller broke but as the story was told to me, the prop split in the middle and fell off its mount, I don't think anything else fell off.
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Nice story, what was the date?
 
SixPapaCharlie said:
So the engine gets down safely? :confused:
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Maybe!

The bridles attach to the very back of the mount, so unless the entire mount sheared off of the firewall, it should still work. It's probably more likely the mount would break farther out, probably at the four bolts that attach the engine-side ring mount to the firewall side of the mount.

If it did shear at the firewall, the bridles would probably just let the engine hang there and I could glide in for a landing. Like a boss.
 
SixPapaCharlie said:
If you are flying and you lose a chunk of it. Not the whole thing but lets say half a blade...
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I'd be very surprised to see half a blade let go. Stress is highest at the hub, and that's where the blade necks (no, no that kind of necking -- NTTAWWT if you REALLY like your plane, but I digress) and further concentrates stress. Most of the cases I've seen reported involve CS props defenestrating a whole blade from its attachment point. You'd nave to break a lot of material to lose just a part.
 
DJTorrente said:
I'd be very surprised to see half a blade let go. Stress is highest at the hub, and that's where the blade necks (no, no that kind of necking -- NTTAWWT if you REALLY like your plane, but I digress) and further concentrates stress. Most of the cases I've seen reported involve CS props defenestrating a whole blade from its attachment point. You'd nave to break a lot of material to lose just a part.
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Yeah but it's a thicker cross section at the hub too. Cracks propagate easier over a thin cross section.
 
NoHeat said:
I wonder if these events are more common with homebuilts, racers, and other experimentals.
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There were 3 or 4 fatal T-18 crashes back when the design first came out because people were cutting down aluminum props that ended up resonating at cruise rpm and failing from fatigue. Type certificated aircraft are more likely to get more of an analysis done to make sure this isn't happening (and sometimes you get rpm bands that are not allowed for normal operation).
 
Sac Arrow said:
Yeah but it's a thicker cross section at the hub too. Cracks propagate easier over a thin cross section.
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I wouldn't say cracks propagate any easier over thin sections than thick....it depends on the stress concentration not the thickness.
 
Capt. Geoffrey Thorpe said:
Type certificated aircraft are more likely to get more of an analysis done to make sure this isn't happening (and sometimes you get rpm bands that are not allowed for normal operation).
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And this, children, is why you pay attention to the RPM and MP restrictions in the POH...
 
Capt. Geoffrey Thorpe said:
There were 3 or 4 fatal T-18 crashes back when the design first came out because people were cutting down aluminum props that ended up resonating at cruise rpm and failing from fatigue. Type certificated aircraft are more likely to get more of an analysis done to make sure this isn't happening (and sometimes you get rpm bands that are not allowed for normal operation).
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A friend of mine lost almost exactly 1/2 of a blade. It was an experimental with a cut and re-twisted aluminum prop. It shook extremely bad and he pulled the power immediately and went to idle cut off. Fortunately he had plenty of altitude and had just passed an airport. He returned and landed successfully.

It ended up trashing the engine's rubber mounts, cracked and twisted a main fuselage longeron, twisted and crinkled one elevator, and slightly creased the firewall. He's convinced had he waited another second or two to kill the engine that it would have departed the plane.

He repaired it and stuck on a wood prop...
 
Father of a friend of mine used to operate Ford Tri-motors for the Forest service. He once told me that his dad had a prop break on one of the outboard engines. It shook loose from the mounts and fell off before they could shut it down. They flew it back to the airport and landed safely on two.

When he told me this I had the mental picture of the Classified ad...
Lost: one aircraft engine in the vicinity of...

The next mental picture was of his dad standing in someones living room saying, Sorry that's not my engine

In reality it landing in a plowed field and they retrieved it.

Brian
 
paflyer said:
It was even cooler when the prop was ducted:
sportaviationcover.jpg
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I remember reading that issue of my dad's Sport Aviation magazine when I was a kid...I think I was 7 or 8. I thought that plane was cool.
 
If the whole prop breaks off from the crankshaft breaking at the front, the thing goes zinging out in front of you as it falls. Its a pretty rare event.
 
And the resultant instantaneous overspeed can cause the engine to come apart and make a mess.
 
In the mid 70's I had a former pvt student of mine buy a brand new Cardinal just after he got his license. He was a farmer so he built a hangar & a gravel strip near his house. His prop always looked terrible from all the nicks it got from the gravel strip. It stood out since it was a brand new airplane.

After he'd had the 177 a year or so he loaded up his wife & two kids & headed for Portland, Or. About 200 nautical miles. While he was over the forest & mountains near Goldendale, WA about 12" of prop came off one of the blades. He said when the extreme shaking started he knew what it was from all of our warnings. He pulled the mixture immediately.

He was able to dead stick the wounded bird onto the Goldendale airport. We still bring this incident up on occasion when we see one another & still acknowledges that he was one lucky sucker that day.

It happens.
 
I used to work for a guy whose father flew Ford Tri-motors for the Forest Service.

He told me the story of a prop breaking on an outboard engine and the engine shaking loose from the mounts and falling off. The flew the plane back to the home airport, only a few miles away with only 2 engines.

I had visions of the Classified add ... "Lost one aircraft engine in the vicinity of...."

The next vision was of them standing in someones living room... "Nope, not my engine"

In reality the picked up the engine out of a farmers, plowed field.

Brian
 
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