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My uncle flew for Mission Aviation Fellowship (maf.org) for a university in Texas, and I believe that he was flying a Cessna to the Amazon (among other places). He actually knew Jim Elliot (who went to the Waodani of Ecuador), the martyr about which the movies "Beyond the Gates of Splendor" and "End of the Spear" were made. He had landed in the Amazon and one of the vanes of his 3-vane propeller broke and flew somewhere off into the jungle. So he got the welder out of the back of the plane, and cut off one of the remaining two vanes and welded it back on at 180 degrees to the one remaining vane. Then he took off and flew home. I love this story, but I always wondered...

How often does a propeller vane just fly off like that?

(And how challenging was that repair?)

Finally, was there any maintenance that would have prevented propeller breakage?


EDIT 1:

From a page from his own memoir that I found online (search for Strash), I found that he definitely flew a Cessna 206 while in the Congo near Kinshasa (then Zaire) in Africa.

Before he worked in Africa, he worked in Suriname in South America, which, indeed, is considered to be part of the immense Amazon jungle. I don't yet know the specific plane he flew while he was there, but a direct contact at the MAF tells me it may have been a Cessna-185 or a Cessna-206.

My mom seemed to recall the story clearly (even though she's 83 and bedridden and I'm caring for her 24/7). Mom said that there was a tree branch that was hit during takeoff, which took off the blade.

If I can get a copy of Uncle John's memoir, the story may be in there.

Bottom line, I know the story was actually told because I received it personally while in his presence and he would have set the record straight at that time if it didn't happen. My recollection of the details may be fuzzy (meaning Amazon or Congo) because that was perhaps approximately 1990 when he visited us in New Jersey.

When this story took place, he may have been in either of those two places, Suriname or Congo.

Here is an early picture of my uncle from his yearbook online, before he became a full professor. He worked both at the MAF, and as a professor teaching Aviation at LeTourneau University, Aviation Technology division.

enter image description here


EDIT 2:

I have to apologize... My story was probably wrong all along. Contacting someone related to MAF directly yielded what I consider to be a more realistic story, which I include here because it's interesting in its own right:

I was unable to verify your uncle’s propeller accident, but when asking around, one person remembered a similar story but it involved John flying a Cessna 185 in Africa where he lost a propeller tip (no welding involved). In order to fly the plane to an MAF repair base, he reportedly sawed the other propeller blade down to match the shorter one and it flew reasonably well out of the jungle until it could get properly fixed—no third blade involved. Of course, this cannot be confirmed, nor did it comply with MAF standards of safety, and it was 60 + years ago.

Now all of your responses make more sense to me. Thanks, everyone!

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    $\begingroup$ Sorry but this story seems extremely implausible. If you lose an entire propeller vane... er... blade, the engine will leave the airplane with the imbalance. What is survivable is losing an inch or so of propeller tip where you shut the engine down right away and glide to a landing. In that case you would just cut off the tips of the other blade or blades the same amount and fly it like that. $\endgroup$
    – John K
    Jun 12, 2023 at 23:46
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    $\begingroup$ Usually, once... $\endgroup$ Jun 13, 2023 at 3:03
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    $\begingroup$ Well, the story as you detailed it is impossible, knowing the way propellers are constructed. A entire blade coming off even on landing would rip the engine from its mounts. And 3 blade propellers are complex machines with blades that are fixed in a hub with bearings so they can rotate. Such a welding repair is not possible. He was embellishing somewhat to enhance the story. It true at all, was likely a inch or so of tip breaking off from metal fatigue, which can happen. If that happened I'd hacksaw off the tips of the other 2 blades to get close to balance again and fly it out. $\endgroup$
    – John K
    Jun 13, 2023 at 4:40
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    $\begingroup$ It seems the answer you want is "as often as God and the angels want them to." But for that christianity.stackexchange.com might be a better fit. $\endgroup$
    – TypeIA
    Jun 13, 2023 at 14:48
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    $\begingroup$ I can't prove it, but you can't disprove it either. That's a bit of a weebly-woobly standard to have. Anyone could come at you with weirdest tall stories and you'd most likely have no way to disprove them. Inability to disprove something has just about nothing to do with how credible something is. It's in fact a common fallacy. $\endgroup$ Jun 13, 2023 at 20:21

4 Answers 4

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A blade of a propeller breaking off in flight is rare, but not unheard of. It can be catastrophic- the imbalance can tear the engine straight off the airplane, and this can happen very quickly.

Unless the blade separating was due to some acute trauma (i.e. hitting something), it's almost certainly a maintenance issue. Either some unnoticed damage to the propeller was allowed to worsen, or the blade was improperly attached to the hub in the first place.

The repair sounds extremely implausible:

  • Propellers take the most abuse of any component on the airplane- centrifugal forces on the base of the blades are in the tens of tons. It seems likely that a field weld would be much weaker than the original propeller and could easily just cause it to separate again in flight.
  • Trying to fly with 2 blades instead of 3 would result in dramatically lower available power (without overspeeding the engine, anyway). Light aircraft don't have that much power margin- I find it unlikely that the plane would be flyable even if the weld held.
  • While having the blades at 180 degrees from each other would reduce the imbalance, it would still be large if the blade were not attached perfectly.
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    $\begingroup$ I can't prove it, but you can't disprove it either. Let's leave it at that. I want to believe my uncle's story. $\endgroup$ Jun 13, 2023 at 5:17
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    $\begingroup$ @MicroservicesOnDDD - en.wikipedia.org/wiki/Russell%27s_teapot $\endgroup$
    – Davor
    Jun 13, 2023 at 12:49
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    $\begingroup$ @MicroservicesOnDDD You're welcome to believe anything you want. I don't see how this repair would be possible, but like you say I can't definitively say it's impossible. $\endgroup$
    – Chris
    Jun 13, 2023 at 15:49
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This is a fine story, but:

When you see real propeller hubs, you'll quickly understand that one does not simply transform a 3 blade into a 2 blade with simple cut and weld methods: 3 blade propeller hub (picture source: e-bay, Smokin Rivet Airparts & Salvage LLC)

As you can see, the hub is not solid. cutting one seat off would leave enormous gaps to fill, and while with proper equipment and environment that would be possible, in field it is not. Attaching the blade directly into the "valley" of the hub would be just as problematic.

As pointed out in Sophit's answer the weldability of the hub material and availability of proper equipment is questionable to say the least, and aligning the blade properly will be a chore. Then there's the imbalance caused by the lost blade as per Chris' answer, which will render the plane pretty much unflyable, quite likely by ripping the whole engine off.

As you stated in your comments, you can't prove this story, but it's pretty much debunked here.

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  • $\begingroup$ While I'm sure what you say is true for what you have shown, this is most likely a more modern development, and when they started MAF shortly after the war, you would have to go on the attachment technology of the day, and I'm sure there's more than one way to make a propeller, or attach blades to it. You would have to show me every way of attachment since World War II to convince me. And somewhere in the showing, my bet is that you'll find a weldable one used by the bush pilots, probably because of its ruggedness, and perhaps for its fixability. $\endgroup$ Jun 14, 2023 at 13:21
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    $\begingroup$ Not gonna argue with you on this. If welding was involved, this is the basic hub design in question, they have not changed since forties. You updated the question to include information that the blade was "lost" during takeoff, there simply is no way that the plane would remain flyable. Full power setting combined with the imbalance (weight & thrust) would rip the engine right off the plane. Is it possible the blade was lost during taxi? Then again, the modifications depicted in the story still aren't plausible. $\endgroup$
    – Jpe61
    Jun 14, 2023 at 13:45
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    $\begingroup$ aviationart.com/products/… $\endgroup$
    – Jpe61
    Jun 14, 2023 at 13:45
  • $\begingroup$ Thanks for letting me see for myself. I hear what you're saying, and now I can see what you are saying, but I'm waiting for my full investigation in seeking out the memoir of my uncle and various books and family member information sources to decide. $\endgroup$ Jun 14, 2023 at 15:36
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    $\begingroup$ The full investigation is in! See EDIT 2 at the end of my question. The tip of a blade was knocked off instead of the entire blade. My uncle then had to even out the blades in order to take off again. $\endgroup$ Jun 16, 2023 at 18:51
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Propeller blades are made either of high-strength aluminium alloy, wood or carbon fibre. None of those materials can be welded, except aluminium but only with very specific equipment (using argon as shielding gas and welding rod based on aluminium).

Just remember the story as it was told and don't ask yourself anything else 🙂

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  • $\begingroup$ I could see propellers being made of hollowed steel with a balsa-wood core, especially when facing flocks of geese or other birds. Are you sure steel has never been used? Landing frequently in the jungle, I would want a particularly tough and resilient propeller. $\endgroup$ Jun 13, 2023 at 19:32
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    $\begingroup$ @MicroservicesOnDDD: the blades can have a so called abrasion or wear strip on the leading edge made of some steel alloy but that's just for protection against dirt. Steel would be susceptible to corrosion. I don't think it has ever been used (except maybe at the beginning of the aviation history when aluminium was too expensive). Anyway the better material for propeller is wood and carbon (or glass) fiber. $\endgroup$
    – sophit
    Jun 13, 2023 at 19:47
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This story is not plausible.

The location would have been Shell Mera in Ecuador. The Amazon is large, but Jim Elliot worked in Ecuador. Several different planes have been used out there. The Piper that was used during the fatal flight was a yellow Piper 14 Family Cruiser, which was light. Several other planes have been used since in Ecuador. Amongst others a Cessna 180 and Cessna 206 Turbo. These are relatively powerful piston engined planes. The propeller would spin at about 3000 RPM, but the torque during takeoff would be enormous.

Reasons why this is not plausible:

  • The propeller blade that departed the plane would probably wreck the plane by breaking the motor mounts.
  • The fracture would not be a clean one, making it extremely difficult to fit another blade to the fracture. As a matter of fact, the fracture would in itself cause an imbalance, unless it is cleanly cut off using a lathe. The Cessna 180 has a constant speed prop. The governor would also not work.
  • The blade is a profiled aluminum blade. A weld would only cover the surface, not the core.
  • A welder in the cargo of the blade is very unlikely. These are extremely heavy loads, as it also needs to be fuel powered, and unlikely a electric transformer type. You don't just tag one along like a wrench, just in case you need it. If it would need electricity, you would be out of luck after an emergency landing, and if it would burn fuel, it will be a fire hazard. If it was in the cargo load, then it's unlikely that there would be aluminum rods to weld, as everything out there would probably be steel. Aluminum welds are hard, and probably need MIG/TIG including the needed gases.
  • (Near) crashes were not uncommon. However, there were always alternatives to get the planes out, for instance with broken gear legs, flat tires, even cylinder failures. The procedure would be easy: call to the base station, describe the needed parts and fly in assistance. Then repair the damage in an authorized way, and fly it out after testing it properly.

I spoke to a retired MAF pilot that was stationed at Shell Mera in Ecuador, and he could probably confirm that this would not have happened. He also wrote a book about his work in Ecuador, and while he told me some wild stories and wrote it all up, it would be hard to explain why he left this story out. There can only be one reason in my mind. It didn't happen.

Can you share more details like the approx date, location and type of plane or even registration?

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    $\begingroup$ Just checked with my source. He is not aware of it. However, he does recall hearing about an incident in which a MAF pilot in Zaire / Congo, involving a two bladed prop, of which a tip broke off. He sawed of an equal part of the other blade, and flew home. with a heavily vibrating engine. At arrival all crankcase bearings were shot. $\endgroup$
    – pnauta
    Jun 13, 2023 at 12:50
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    $\begingroup$ @Chris-RegenerateResponse Nothing stopping you from doing that with a CS prop. A blade tip is a blade tip. Flying home with missing propeller blade tips after sawing off the opposite side has been done in the Canadian bush, and I'm sure all sorts of places over the years. If you could remove the prop and had a way to suspend or support it on its center axis, you could achieve a fairly good static balance with lots of filing. Otherwise It comes down to making the finished cut as close to the other side's length as possible. $\endgroup$
    – John K
    Jun 13, 2023 at 16:44
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    $\begingroup$ @JohnK Sawing off a blade tip is fine. Removing one blade and putting it somewhere where there never was a blade to begin with, like in OP's story, is obviously impossible with a CS prop. If you just weld it to the hub, its pitch obviously wouldn't change, and I can't imagine a plane with one variable pitch blade and one constant pitch blade would be flyable. $\endgroup$
    – Chris
    Jun 13, 2023 at 16:49
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    $\begingroup$ One correction (possibly): there are very compact and light alternator driven stick welders, although I'm not sure that was the case back in the days. One could weld aluminum with such a device, but as stated many a times here, not a propeller hub. Just nope. $\endgroup$
    – Jpe61
    Jun 13, 2023 at 19:27
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    $\begingroup$ Typos: "A welder in the cargo of the blade ..."; "If it was in the cargo load, ..." $\endgroup$ Jun 13, 2023 at 20:44

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