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(BBC)   Wrong propeller bolts make propeller bolt   (bbc.co.uk) divider line
    More: Scary, misinterpretation of an engine manufacturer, result of this accident, Result, Accident, Torque, Safety, engine manufacturer, incorrect bolt length  
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3993 clicks; posted to Main » on 11 Aug 2022 at 5:35 PM (7 weeks ago)   |   Favorite    |   share:  Share on Twitter share via Email Share on Facebook



49 Comments     (+0 »)
View Voting Results: Smartest and Funniest
 
2022-08-11 3:27:07 PM  
Fark user imageView Full Size
 
2022-08-11 5:38:58 PM  
Lock washers are your friend.
 
2022-08-11 5:39:31 PM  
At first I thought that it was a boat propeller....then I clicked on the link.  Jeez!
 
2022-08-11 5:43:03 PM  
It was always drilled in that if something bad happens just after takeoff you're best to find a spot straight ahead rather than turn around and head back to the field. That 180° turn just loses you too much altitude if you have no thrust.
 
2022-08-11 5:47:05 PM  
That's a Schroedinger's Pilot:
Simultaneously Lucky and Unlucky to have it happen but  at least make it down alive.
 
2022-08-11 5:49:54 PM  
Losing a bolt'll jolt ya.
 
2022-08-11 5:50:56 PM  
So, the right propeller bolts and it was due to improper bolting?
 
2022-08-11 5:51:00 PM  
Fark user imageView Full Size
 
2022-08-11 5:52:23 PM  
Propeller driven plane, suddenly glider!

The propeller lost in the incident has not been found.

I assume it flew off to elope and live its life with a jet engine.
 
2022-08-11 5:54:19 PM  
They probably messed up the metric to imperial conversion
 
2022-08-11 6:02:24 PM  
It was a 1939 Aeronca. Those things are legendary badasses. The article stated that the pilot turned around to land not knowing the propeller had fallen off.
 
2022-08-11 6:03:28 PM  
Of all the things that could fall from the sky, I'm trying to imagine something more disconcerting than an airplane propeller.
 
2022-08-11 6:05:06 PM  
I once has the front caliber breaka on a mountain bike pop off while going down a rather steep path. I'd imagine this felt worse.
 
2022-08-11 6:05:51 PM  

Sumo Surfer: Of all the things that could fall from the sky, I'm trying to imagine something more disconcerting than an airplane propeller.


thumbs.gfycat.comView Full Size
 
2022-08-11 6:06:04 PM  
Real question: What does shanked mean in this context? Ripped out from over-torquing?

- Sofa
 
2022-08-11 6:07:59 PM  
If you read the article you might have come across this

"The pilot attempted to return to the airfield but crashed through a hedge at the end of the runway."

or this

"Despite managing to line up a return to the field, the plane was travelling too fast when the pilot touched down."

The pilot made it back, with too much airspeed, and overshot the runway
 
2022-08-11 6:10:11 PM  
That was a nice-looking plane, I hope it can be repaired
 
2022-08-11 6:14:05 PM  

Sofakinbd: Real question: What does shanked mean in this context? Ripped out from over-torquing?

- Sofa


That's what it sounds like. Per the article the prop might have had incorrectly sized bolts. If they were too short they would not have had enough thread to hold the prop at the correct torque, so technically "over-torquing" the bolts off the flange.
 
2022-08-11 6:15:51 PM  
Damn. That's nuts.
 
2022-08-11 6:16:51 PM  

Sofakinbd: Real question: What does shanked mean in this context? Ripped out from over-torquing?

- Sofa


It means the bolt has stretched - it got narrower and weaker in the middle. Like pulling taffy.
 
2022-08-11 6:21:18 PM  

Sofakinbd: Real question: What does shanked mean in this context? Ripped out from over-torquing?

- Sofa


A fellow prisoner sharpened the bolts and stabbed him in the kidney.
 
2022-08-11 6:21:26 PM  

aremmes: Sofakinbd: Real question: What does shanked mean in this context? Ripped out from over-torquing?

- Sofa

That's what it sounds like. Per the article the prop might have had incorrectly sized bolts. If they were too short they would not have had enough thread to hold the prop at the correct torque, so technically "over-torquing" the bolts off the flange.


Over-torquing your bolts off your flange can also cause blindness, hairy palms
 
2022-08-11 6:22:47 PM  
"
The propeller lost in the incident has not been found."

I swear I saw it on the wall over a Shenanigans
 
2022-08-11 6:24:46 PM  
The propeller is just there to keep the pilot cool.  Because if it comes off, they will start sweating.
 
2022-08-11 6:41:20 PM  

vudukungfu: "
The propeller lost in the incident has not been found."

I swear I saw it on the wall over a Shenanigans


Hey, Farva, what's the place you like to go to with all of that kitschy shiat on the walls?
 
2022-08-11 6:54:19 PM  

yellowjester: So, the right propeller bolts and it was due to improper bolting?


Aw nuts.
 
2022-08-11 6:55:14 PM  

snowybunting: Lock washers are your friend.


Wire that shiat down, too.
 
2022-08-11 7:03:56 PM  

OkieDookie: snowybunting: Lock washers are your friend.

Wire that shiat down, too.


Lock washers are not used in most propellor installations. Instead of bolts too short, bolt slightly too long will reach end of threads and display proper torque even though the prop isn't tight enough. The smallest movement of prop under power will quickly stretch and break the bolts at the shoulder where the threads begin.

/Been there, seen that
 
2022-08-11 7:05:05 PM  
Props to that pilot, since we aren't doing phrasing today
 
2022-08-11 7:10:34 PM  

Sofakinbd: Real question: What does shanked mean in this context? Ripped out from over-torquing?

- Sofa


The bolts will have a section on them that isn't threaded near the head. It's usually also larger in diameter. That give a nice smooth spot for the propeller to drive against instead of getting loaded against the edges of the threads. That shank also can stop from crushing the propeller. If it's the right size it will clamp the propeller the right amount and then bottom on the shank before clamping to much.
I would guess they had bolts where the shank was to long so it either didn't clamp the propeller enough, or they didn't have enough threads past the shank so it didn't have enough strength and pulled the threads.
 
2022-08-11 7:13:55 PM  
dygtyjqp7pi0m.cloudfront.netView Full Size

Should have used these instead, they're self sealing.
 
2022-08-11 7:49:46 PM  
Oopsie!
 
2022-08-11 7:56:18 PM  

NBSV: Sofakinbd: Real question: What does shanked mean in this context? Ripped out from over-torquing?

- Sofa

The bolts will have a section on them that isn't threaded near the head. It's usually also larger in diameter. That give a nice smooth spot for the propeller to drive against instead of getting loaded against the edges of the threads. That shank also can stop from crushing the propeller. If it's the right size it will clamp the propeller the right amount and then bottom on the shank before clamping to much.
I would guess they had bolts where the shank was to long so it either didn't clamp the propeller enough, or they didn't have enough threads past the shank so it didn't have enough strength and pulled the threads.


That's what I think they mean by shanked. To hopefully expand on this, it can be where the bolts are too long. With slightly longer bolts than specified, the shank is long enough to prevent the proper amount of clamping force, similar to bottoming out in a blind hole.
 
2022-08-11 7:57:13 PM  

Nocrash: OkieDookie: snowybunting: Lock washers are your friend.

Wire that shiat down, too.

Lock washers are not used in most propellor installations. Instead of bolts too short, bolt slightly too long will reach end of threads and display proper torque even though the prop isn't tight enough. The smallest movement of prop under power will quickly stretch and break the bolts at the shoulder where the threads begin.

/Been there, seen that


/knows a thing or two about bottoming out while screwing hard.
 
2022-08-11 7:58:28 PM  
Many parts have a torque spec. GüdNTite is not for everything?
 
2022-08-11 8:05:19 PM  

petec: If you read the article you might have come across this

"The pilot attempted to return to the airfield but crashed through a hedge at the end of the runway."

or this

"Despite managing to line up a return to the field, the plane was travelling too fast when the pilot touched down."

The pilot made it back, with too much airspeed, and overshot the runway


Jesus, it sounds like the plane barely needed the prop in the first place. Didn't slow it down much losing it
 
2022-08-11 8:09:18 PM  

Nocrash: OkieDookie: snowybunting: Lock washers are your friend.

Wire that shiat down, too.

Lock washers are not used in most propellor installations. Instead of bolts too short, bolt slightly too long will reach end of threads and display proper torque even though the prop isn't tight enough. The smallest movement of prop under power will quickly stretch and break the bolts at the shoulder where the threads begin.

/Been there, seen that



I agree with not wanting too long of a bolt - having it twist while tightening is an issue - but a lock washer would only lengthen an M8 about 1/8" I would guess. But I am not an engineer, so maybe that is enough to weaken the bolt.
 
2022-08-11 8:34:46 PM  

snowybunting: Lock washers are your friend.


Safety wires are a better friend
 
2022-08-11 8:41:17 PM  

Boojum2k: petec: If you read the article you might have come across this

"The pilot attempted to return to the airfield but crashed through a hedge at the end of the runway."

or this

"Despite managing to line up a return to the field, the plane was travelling too fast when the pilot touched down."

The pilot made it back, with too much airspeed, and overshot the runway

Jesus, it sounds like the plane barely needed the prop in the first place. Didn't slow it down much losing it


I have flown in a Champ. You could almost get there faster by walking. It has the look of something bolted together over the weekend in somebody's garage, with a VW engine stuck on the front. The main spar in the wing is a spruce board and the wing gets its shape from a bunch of stamped aluminum ribs that slide onto the spar.

It's a lovely, simple aircraft, and I hope this one can fly again...if there's not too much damage, it's very rebuildable...in someone's garage if need be.
 
2022-08-11 8:42:46 PM  
Was so sure this was Birch
 
2022-08-11 8:43:55 PM  
Ooops! Was so sure this was Birchwood Alaska, where equally goofy things happen alarmingly often.
 
2022-08-11 8:47:12 PM  
When the prop falls off, the center of gravity shifts backwards and it can shift too far back for the plane to handle correctly.  It sounds the like pilot might have been confused about why the engine was spinning too fast as well and it might have been way above the normal landing speed even with the throttle all the way back.

Setting up for a proper landing is mostly done by RPM.  You set the RPM and check for your desired speed a few seconds latter and then make minor adjustments. A plane tachometer is good enough to see changes of 50 PRM. If cruise is about 3,000 RPM, you get in the pattern at say 2,000 RPM and then drop to 1,800 or 1,500 RPM on final approach.  Most planes will do at least 800 RPM when the throttle is all the way back assuming the prop is still on.
 
2022-08-11 8:47:30 PM  

snowybunting: Nocrash: OkieDookie: snowybunting: Lock washers are your friend.

Wire that shiat down, too.

Lock washers are not used in most propellor installations. Instead of bolts too short, bolt slightly too long will reach end of threads and display proper torque even though the prop isn't tight enough. The smallest movement of prop under power will quickly stretch and break the bolts at the shoulder where the threads begin.

/Been there, seen that


I agree with not wanting too long of a bolt - having it twist while tightening is an issue - but a lock washer would only lengthen an M8 about 1/8" I would guess. But I am not an engineer, so maybe that is enough to weaken the bolt.


The extra thickness of a lock washer isn't really a problem. It's more that they don't really work all that well. You're relying on the washer being able to dig into the metal enough it doesn't want to loosen. In reality often the washer looses its spring and doesn't bite into anything. Even the fancy nord lock washers are better, but don't always work well enough.
For something like a prop safety wire, bent tabs on a plate, or some sort of positive locking would be the way to go.
 
2022-08-11 9:04:23 PM  

NBSV: snowybunting: Nocrash: OkieDookie: snowybunting: Lock washers are your friend.

Wire that shiat down, too.

Lock washers are not used in most propellor installations. Instead of bolts too short, bolt slightly too long will reach end of threads and display proper torque even though the prop isn't tight enough. The smallest movement of prop under power will quickly stretch and break the bolts at the shoulder where the threads begin.

/Been there, seen that


I agree with not wanting too long of a bolt - having it twist while tightening is an issue - but a lock washer would only lengthen an M8 about 1/8" I would guess. But I am not an engineer, so maybe that is enough to weaken the bolt.

The extra thickness of a lock washer isn't really a problem. It's more that they don't really work all that well. You're relying on the washer being able to dig into the metal enough it doesn't want to loosen. In reality often the washer looses its spring and doesn't bite into anything. Even the fancy nord lock washers are better, but don't always work well enough.
For something like a prop safety wire, bent tabs on a plate, or some sort of positive locking would be the way to go.


Exactly right. Lock washers are sometimes used on non-rotating engine components but they must be discarded after a single use and replaced with new ones every time. Never reuse a lock washer.
 
2022-08-11 9:44:10 PM  

Nocrash: Exactly right. Lock washers are sometimes used on non-rotating engine components but they must be discarded after a single use and replaced with new ones every time. Never reuse a lock washer.


Username checks out.
 
2022-08-11 11:24:31 PM  

Russ1642: It was always drilled in that if something bad happens just after takeoff you're best to find a spot straight ahead rather than turn around and head back to the field. That 180° turn just loses you too much altitude if you have no thrust.


Depends on the plane.  This has become an item of much discussion and testing the last few years. Some planes can do it. A Bonanza? Never.

Don't know about this model.
 
2022-08-12 1:04:01 AM  

edmo: Russ1642: It was always drilled in that if something bad happens just after takeoff you're best to find a spot straight ahead rather than turn around and head back to the field. That 180° turn just loses you too much altitude if you have no thrust.

Depends on the plane.  This has become an item of much discussion and testing the last few years. Some planes can do it. A Bonanza? Never.

Don't know about this model.


The general rule is below 400 ft above the ground, don't go back.
This plane might make it at 200 foot.

I was renting a plane and on the checkout, the owner cut the throttle at 200 AGL and put it cleanly back on the runway.  It was his plane and his runway and it was large for training and to service planes in WWII.  It is surrounded by farm fields except for the flood plain, swamps and the wet part of the Mississippi river just past the end of the runway.  On that airport anyway but straight would be better when the engine stops turning.  I got the warrior down on the runway but poorly aligned and it was wide enough to keep it on the paved part.
The owner did ask me how I felt about landing on non-paved areas and I mentioned I had landed a glider on grass once and he went into a tirade about how the insurance companies won't let young pilots land on grass strips.  Oddly enough when I first meet him, he said "Your not so and so's kid but you look like them so you must be a cousin" and named my uncle.  He apparently went to the same one room school house my father walked uphill both ways in the snow to get to.
 
2022-08-12 8:20:14 AM  

Sumo Surfer: Of all the things that could fall from the sky, I'm trying to imagine something more disconcerting than an airplane propeller.


Wing, or wings
 
2022-08-13 6:12:13 AM  

Habitual Cynic: Sumo Surfer: Of all the things that could fall from the sky, I'm trying to imagine something more disconcerting than an airplane propeller.

Wing, or wings


A baby?
 
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