Pilots, how bad is losing a propeller

The situation is that you’re in a home built, 2-seat, single engine aircraft, at altitude on a clear day. The propeller falls off. How bad is this situation?

You mean. how bad for the pilot, or how bad for the people on the ground trying to dodge a falling propeller?

The plane will have a glide angle that will enable it to be landed safely, provided there is a safe terrain nearby, a variable the OP did not reference.

I guess one fairly certain thing is that the plane will never resume power again before ground repairs are effected. IOW, there is no fix.

Some clarifying questions, since this references a real incident –

  1. How stressful would this situation be? My thought is “only moderately,” since it’s real-life and all that, but something that pilots should have practiced multiple times in order get their license, right?
  2. Barring any damage to the control surfaces from prop debris, would the plane be any harder to fly than normal? The pilot supposedly dislocated his shoulder just trying to wrangle the plane onto the runway.
  3. The pilot was able to make it to the runway, but the plane flipped over and rolled, causing additional injury. I wouldn’t think there would be a high risk of that as long as all of the control surfaces were still operational. Correct?

You have to realize that a plane is very precisely balanced. Every time a pilot flies he/she calculates exactly where the center of gravity of the plane is based on the weight aboard in inches from the most forward place on the plane, in this case the propeller that is no longer there, as a result the plane is completely off balance. Couple that with the fact that pilots often use the engine to make adjustments to altitude, faster makes you go higher, and losing your only propeller is going to give you a bad day. Yes they practice no engine maneuvers and landings in pilots school however you don’t actually land the plane in the middle of the field so you break off long before that. Also how long ago was pilots school?

Early in my flight lessons, my instructor pulled back the throttle and said “You just lost your engine. Now what?” It was pretty straightforward to identify a safe place to set down and set up to land. The major stress is knowing you only have one shot at it but if you’re not in the middle of the ocean or way too low, it’s not a huge deal.

I don’t think a missing prop would affect the flight characteristics to any noticeable degree - you’re just flying a glider now.

He landed on a runway and flipped? That just sounds to me like a bad landing - the prop shouldn’t have had anything to do with it. We had a guy in our flying club flip a plane, but he did a lot of things wrong to accomplish that. Barring hideous winds, I can’t imagine flipping on a paved surface.

Disclaimer: I haven’t piloted a plane in nearly 40 years, so maybe I don’t know what I’m talking about.

I was thinking the same thing. Assuming this is a conventional layout with a tractor (at the front) propeller, losing it is gonna make the plane tail-heavy. You can push the yoke forward (or use the trim) to keep the nose down, but (if I remember correctly) the force generated by the elevator will decrease as the plane slows down (which could make the nose rise, which would slow you down more, etc.).

Heavy prop, very front, small plane (the OP said 2-seat); I’d have to run the numbers to see if this moved the CG beyond limits. I wouldn’t just assume that it’s no big deal. If I was in the plane and this happened, and I didn’t have those numbers, there’d be a lot going through my head about how to get this on the ground safely.

“Precisely” is relative. the center of mass needs to be located within a specific range, but it’s not like that range is +/- 0.005 inches.

Case in point, this aerobatic plane loses its prop at t=6:00, and the airplane remains flyable. The primary hazard is the same as if the engine shuts down: you better have enough altitude and airspeed to make your way to a flat, clear area for an emergency landing, and get it right on the first approach. In this case, he was able to get to the runway and make a safe landing.

Other planes might be different, e.g. if the pilot has already loaded the plane with passengers/luggage/fuel such that the CG is already at its aft limit, the plane might be rendered unstable (needing constant attention to the controls) or totally unflyable (see e.g. National Airlines flight 102 - not a prop loss, but an excessive CG shift in mid-flight).

The propeller is only there to keep the pilot cool. If it falls off or stops moving, the pilot really starts sweating.

Losing the prop entirely is not going to adversely affect the CG. Many planes have the fuel tank in front of the CG. For instance, in the plane I have the most hours in, there’s a 12 gallon tank in front of the CG. If I were to take off and burn 10 gallons, that’s losing 60 lbs of nose weight. The plane doesn’t handle any differently.

I guess if the plane were already on the verge of being uncontrollably tail heavy - but that shouldn’t happen anyway.

Then again, if your prop falls off several safety measures have already failed.

And what are the chances the plane will crash into the propeller? I imagine if, for example, the propeller shaft failed, the propeller will fly forward for a split second (because up until that time, the propeller was pulling the plane forward). Then air resistance will quickly stop the rotation and forward motion of the free-flying propeller.

But the instant it breaks free of the plane it will also start accelerating downward under the influence of gravity. Assuming the plane wasn’t already on a ballistic trajectory, then prop and aircraft should soon end up far apart.

I imagine how bad is inversely proportional to how many propellers the aircraft has.

IANAP but I’ve heard that it can be worse for a twin-prop to suddenly lose one propellor; plane then has off-center thrust.

One of the guys in my college skydiving club was up in the DZ’s Beech Twin Bonanza when it lost a prop. He said that nobody panicked but the pilot had the jumpmaster get all the students out really fast (for static line jumps there was a routine you’d follow to get students out, they got the Cliff Notes version - "Next! Sit in the door! Go! Next!..) and the experienced jumpers then skedaddled.

Pilot landed just fine, FAA showed up to inspect; I understand there had been several such incidents with that model and this was one of the first where they could actually recover the prop (it landed in a farmer’s field nearby).

Mostly as others have said.

The prop magically disappearing is no big deal. The CG shift will be tolerable for all but the most extreme cases. Then it’s just a matter of getting over the surprise and executing a forced landing. If favorable terrain is available and you’re at a decent altitude you’ll almost certainly walk away. Especially in most homebuilts that have particularly slow landing speeds. Even if you crash during the landing it’ll be slowly.

Make no mistake. Any aircraft emergency badly handled is more than able to kill all aboard and the same number again on the ground. But assuming favorable altitude and terrain this one is pretty much in the middle of the envelope of stuff pilots, even weekend pilots, are supposed to be able to handle. And usually do.
An issue is that as soon as the prop disappears the engine will try to overspeed. If you figure that out quickly & close the throttle you’ll be fine. If not you *will *blow up the engine. Very soon. At which point you may have a fire in the engine compartment, oil covering the windshield, and/or other complicators[sup]1[/sup]
In the real world propellers don’t disappear. Instead something breaks and they separate from the aircraft. If that happens in a neat and balanced way all is mostly well as described above.

If instead it sheds half or all of a blade now you’ve got a whole 'nother kettle of fish. The ensuing unbalanced vibration can tear the engine off its mounts, bend the aircraft, or shake the pilot so bad he/she can’t see or think. Airplanes have come completely apart in flight precipitated by a propeller failure. See some of the YouTubes of bricks in clothes dryers for an idea of what happens.[sup]2[/sup]
Historically some prop losses have happened from defective crankshaft machining where the crank severs forward of the first cylinder. Then the prop’s thrust pulls the crank stub out of the front of the engine. The good news is the prop departs cleanly as a unit so you’re balanced. The bad news is lots of engine oil comes out too. Which ends up all over the windshield. And depending on the details the engine may keep running so you still have an overspeed to deal with pretty much instantly.
The departing prop whacking the airframe and causing further damage is usually unlikely. Not impossible, but not the biggest joker in the deck. At least for a typical tractor design.

OTOH, prop losses on aircraft like these are all but guaranteed to whack the tail with probably catastrophic results: Republic RC-3 Seabee - Wikipedia
Lake Buccaneer - Wikipedia
Trident TR-1 Trigull - Wikipedia
Thurston Teal - Wikipedia
Osprey Osprey 2 - Wikipedia

Only the last of these are homebuilt.

  1. Aside: I once sold a high performance car to a guy. The next day the throttle stuck full open on the freeway. His response was to push in the clutch & shift to neutral. About 5 seconds later at about 2x redline RPM the engine came unglued. There was oil everywhere, two jugs blown out, one piston stuck through the sheet metal engine compartment walls. An unholy mess. He should have switched off the ignition instead. Would’ve been a non-event had he done so. Destroyed a $10K engine in about 5 seconds. He would not have done well with a prop loss inflight.

  2. This Braniff International Airways Flight 542 - Wikipedia is the story of something broadly similar that took out a couple of these airliners. In these cases the props stayed attached, but engine vibrations very similar to what you’d experience with a half-missing prop tore the wing clean off. Obviously not a pilotable or survivable failure mode.

If on a Helicopter–pretty bad.

In that case, I’d suggest turning straight around & going home.

Whelp, the OP specified a homebuilt two seater aircraft without stating if it was an ultra-light airplane, or a more conventional enclosed type aircraft, is it a kit based on a known and proven design or, does home-built also mean home designed and/or experimental and unproven? Is it a gyro? missed steronz second post…dammit

@guestchaz: Don’t feel bad. I read the thread but had skimmed right over that too. Until you pointed it out.

  1. It *is *stressful as in “Do this right or you’ll die a violent death in the next few minutes. Or be crippled forever.” You can practice this stuff all you want, but nobody knows how they’ll really react until the first time they have a no-shitter.

Experience with close calls in cars is not real informative because most car accidents or almost-accidents transition from normal to either crashed or “Whew!!” in the space of just a few seconds or less. Airplane emergencies are more long drawn out tension-inducing affairs. Retaining a clear head while wasting a 6 month supply of adrenaline is an attribute you either have … or don’t. Training helps, but there’s always a wildcard here.
2) If this is an ultralight, and depending on other design details, and depending on what broke, the airplane might be enough out of balance to require real heavy control forces. Dislocating a shoulder sounds implausible from just that, but not impossible. People have certainly torn muscles or worse just using their own muscles. OTOH, if the airplane crumpled on landing the dislocation may stem from that and you’re just reading a garbled news report.
3) A truly bad hard landing often degenerates into a rollover. If the guy was low on energy he may not have been well aligned with the runway. So at the last moment he’s trying to turn to align. Which sets up the rotation that leads to disaster in a hard bounce.

If low on energy he may also have been flying more slowly than normal trying to “stretch the glide” as we say. It doesn’t work, but it is tempting. Getting slow leads to being unable to arrest the descent rate before touchdown. So you hit, bounce up 10 to 20 feet, then quit flying and fall back to Earth. Odds are you’re not gonna land flat in that case.

The other possibility is he’s high on energy and trying to force the airplane onto the ground at too high a speed. Mindful of the other end of the runway approaching this isn’t too bad an idea once you find yourself stuck in that situation. But making the airplane stick to the ground at higher than normal speed is real hard. And often ends in tears/tears. Both as in ripped metal and as in crying pilots/owners.

If you’re in “Anything that even vaguely resembles a runway!” mode, you could easily aim for the nearest open field, big straight highway, or even an actual runway without any thought to wind conditions and inadvertently land on a bad crosswind.

Google “crosswind landing” to see plenty of hair-raising videos of landings done by people who are *expecting *a difficult landing to get an idea of what crosswind can do to an airplane.

In the mid-'70s my dad had just bought a used Cessna 172K. Gibbs Flight Service was flying it from San Diego up to him in Lancaster. About six inches of prop departed the aircraft over Orange County. There was severe vibration, and the pilot shut down the engine immediately. He made a dead-stick landing at MCAS El Toro. Afterward, the engine was magnafluxed to check for damage (there was none) and Gibbs put on a brand new ‘$800 cruise prop’. (I wonder what a new prop goes for today?)

Loosing an engine is kind of rare. Has happened a few times. Lost it off the airplane. One little 2 seater pilot lived because he instantly went vertical downward so the out of CG condition would not make the plane uncontrollable. He flared just right and at the correct instant to make the landing.
Engine failing to continuing running happens much more often and it too is called ‘losing an engine’.

Not controlling engine over speed is the biggie in a total loss of prop.

As stated in posts above.

I just wanted to add about the little guy who’s engine actually fell off.