What engine is more reliable a piston Helicopter or a single engine airplane?

FloridaPilot

FloridaPilot

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I spoke to a Helicopter pilot and he said: "The Engine and model are pretty much the same, (Lycoming) but a Helicopter engine HAS to be more reliable because if the engine fails not many options exist, you don't hear about too many Helicopter accidents compared to Airplane accidents"

(IMO) I believe around here (FL) there are more airplanes flying then helicopters. I don't see too many helicopters flying around just a small hand full.
 
This question is hard to answer. Overall I would say that two identical engines, one installed in helicopter and one in the airplane, the airplane engine will be more reliable. In general the way helicopters achieve reliability is by replacing things before they have a chance to break.
 
Well, the reason you don’t hear about helicopters as often is simply that, there’s not as many flying.

I’ve heard the same be told about fixed wing, especially in single engine aircraft, “they have to be reliable, because there’s only one.”

I would be interested to see how the two compare statistically, although I would imagine it’s rather difficult to measure.

Comparing the two, the fixed wing has a horizontally opposed engine, while the helicopter utilizes a vertically opposed variant. The two engines are nearly identical other than that, if we’re talking Lycoming.

In my limited experiences in rotorwing as a passenger, the throttle is always ran at 100% continuously throughout the flight (R22, R44 & Bell 206) whereas a fixed wing engine is not. This could play a role in the average longevity and/or failure rate of an engine, depending on how aggressive it’s been operated.

Look to see what the rotor heads on the board have to say.
 
Not all helicopters use vertical engines...a lot of them are horizontal just like the fixed wing. They don't always run at 100% power either. They are just like the fixed wing setup in that they strive to be constant speed through the control of the throttle and blade pitch. Pitch and power are controlled separately by the pilot.
As for which is more reliable its probably a toss up. You are of course less likely to have prop strike with the heli and the engine is separated from the rotor by a clutch so wouldn't' have the same loads applied in a strike anyway.

Frank
 
FloridaPilot said:
I spoke to a Helicopter pilot and he said: "The Engine and model are pretty much the same, (Lycoming) but a Helicopter engine HAS to be more reliable because if the engine fails not many options exist, you don't hear about too many Helicopter accidents compared to Airplane accidents"

(IMO) I believe around here (FL) there are more airplanes flying then helicopters. I don't see too many helicopters flying around just a small hand full.
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I can't speak to the relative engine reliability with respect to planes and helicopters, nor am I a helicopter pilot, but I do question the comment indicating that there are fewer options in case of helicopter engine failure. I understand that a helicopter can be made to auto rotate and land in a very small space compared to most planes, given a sufficient altitude for the pilot to react and configure the rotor.

Any thoughts about that?
 
The Robinson helicopters use de-rated Lycomings. Most other "modern" helicopters use turbines. Turbines are far more reliable and expensive than piston engines. And they burn a lot more fuel.
 
Cap'n Jack said:
I can't speak to the relative engine reliability with respect to planes and helicopters, nor am I a helicopter pilot, but I do question the comment indicating that there are fewer options in case of helicopter engine failure. I understand that a helicopter can be made to auto rotate and land in a very small space compared to most planes, given a sufficient altitude for the pilot to react and configure the rotor.

Any thoughts about that?
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Can watch’em practice autorotations nearly every day at BJC. They don’t have much glide range so that part alone limits options. Add in the observation that helicopter pilots are somewhat like crop dusters and are unable to fly very far above ground and the options are truly limited. How that actually plays out is prolly another story entirely.
 
One has a horizontal rotary wing and can land power off very short. The other has a horizontal fixed wing and has a better glide ratio. Apples and oranges.
 
FloridaPilot said:
I spoke to a Helicopter pilot and he said: "The Engine and model are pretty much the same, (Lycoming) but a Helicopter engine HAS to be more reliable because if the engine fails not many options exist, you don't hear about too many Helicopter accidents compared to Airplane accidents"

(IMO) I believe around here (FL) there are more airplanes flying then helicopters. I don't see too many helicopters flying around just a small hand full.
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You would be surprised by how many helicopter accidents are in the NTSB data base every month. They are inherently more complex to operate and I believe they are significantly more to insure.
 
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The main commonality is that with fixed wing or rotor wing, when the motor quits, you land. Preferably a controlled landing.

I have 0.5 hours of rotor time and we autorotated once. Was actually kind of fun.
 
Piston helicopter = e^n reciprocating parts, rapidly headed toward their time limited fatigue life in unison.
 
BiffJ said:
Not all helicopters use vertical engines...a lot of them are horizontal just like the fixed wing. They don't always run at 100% power either. They are just like the fixed wing setup in that they strive to be constant speed through the control of the throttle and blade pitch. Pitch and power are controlled separately by the pilot.
As for which is more reliable its probably a toss up. You are of course less likely to have prop strike with the heli and the engine is separated from the rotor by a clutch so wouldn't' have the same loads applied in a strike anyway.

Frank
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:yeahthat:

The Robinson R22 has the Lycoming mounted horizontally, like in an airplane. But it is derated for both take-off and continuous operation compared to the fixed-wing equivalent displacement Lycoming engine.
 
FlyingTiger said:
You would be surprised by how many helicopter accidents are in the NTSB data base every month. They are inherently more complex to operate and I believe they are significantly more to insure.
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They are landed in some pretty awkward places involving weird winds, uneven or cluttered or soft ground, surrounding obstacles. I read of one that caught the forward end of a skid under a protruding tree root and flipped over when the pilot lifted off.

Engines aside, the helicopter is far more mechanically complex than a fixed-wing and therefore has many more failure points. Critical failure points. A mast bearing, gearbox component, link rod, whatever--all of that stuff has to be there and be working or the thing crashes. There have been fixed-wings that suffer a control system failure, like a broken elevator cable, and the pilot has landed using trim and power. Helicopter doesn't have such options.
 
The majority of piston helicopter accidents are training related. Real engine failures get lost in the noise.
 
1. I'd like to think that helicopters have more options than planes in the event of an engine failure. Like airplane pilots you're always looking for a good spot to set it down in the event of an emergency. Planning ahead is key. For helicopters you just need a clear flat surface for a more vertical approach, whereas for airplanes you need more horizontal space to glide to a landing.

2. The loss of an engine in a helicopter isn't as critical as most people think. Yes, you're coming down at an accelerated rate but it's a controlled descent via autorotation. And you should be practicing autos constantly. The first thing you do is drop the collective to keep the rotor speed in the green arc. Everything else is secondary to that. Find a place to set it down and maneuver the ship so you have a good approach at a good airspeed. Just prior to touching down you'll flare and pull collective and cyclic, which slows both your rate of descent and your airspeed.

3. I wish I had the stats now, but my primary helicopter CFI had some stats showing that Robinson's piston helicopters have fewer engine failures than most turbines. I'm the first to say statistics can be bent to show what you want to see, but it was comforting to read the article and charts.

4. Yes, there are exponentially more airplanes than helicopters because of cost. Everything about helicopters is more expensive. Especially the insurance.

5. Planes are fun. Helicopters are really, really fun.
 
Okay, admittedly I am not a helicopter pilot but regarding auto rotations, isn't airspeed critical in order to keep the rotor speed up? Doesn't that mean there is a horizontal component to an emergency helicopter landing?
 
Airspeed is a factor, but pitch (the angle of the main rotor blades) is primary. If rotor speed gets too low the blades lose lift and will cone. There's a point of no return though where it's too far to recover.
 
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The engines use primarily the same parts. There is no difference. Any reliability difference statistically would have to do with operation.
 
Stewartb said:
Okay, admittedly I am not a helicopter pilot but regarding auto rotations, isn't airspeed critical in order to keep the rotor speed up? Doesn't that mean there is a horizontal component to an emergency helicopter landing?
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Airspeed isn't much of a factor in maintaining Nr in the descent but it is a factor in maintaining Nr at touchdown. Which is ultimately what matters most.

Example, you have two helicopters at a 1,000 ft hover. Both enter an auto, one does a vertical auto at 0 airspeed and the other noses over to hit say 60 kts. Going down, the vertical auto will have a high Nr and a high rate of descent. The 60 kt auto will have a normal Nr (100 % + -) and a normal rate of descent (1800-2000 FPM) The vertical auto will bleed that Nr much more rapidly because of the increased induced flow & profile drag when collective is applied at the bottom. The result will be a low Nr alarm with an accident where at the very least, the landing gear will be crushed and most likely, tail boom cut off. Since the 60 kt auto has a much shallower angle and has the benefit of increased up flow from forward movement, just aft cyclic alone will arrest the descent while maintaining/ increasing Nr. All that's left is cushion with collective.

Of course a lot of maintaining Nr depends on type aircraft. Obviously a high inertia rotor vs a low inertia rotor being the primary factor.
 
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This thread got me looking at helo crashes. Tail rotor strikes seems like a common problem.

 
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FlyingTiger said:
This thread got me looking at helo crashes. Tail rotor strikes seems like a common problem.

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Well that's a loss of tail rotor thrust due to the fact the tail rotor departed the aircraft. That was followed by a tail boom strike due to the fact the aircraft became uncontrollable. Both of those aren't common in helicopters.
 
The one with the less moving parts and less strain and most amount of airflow I'd guess, with a emphasis on the moving parts.
 
Velocity173 said:
Well that's a loss of tail rotor thrust due to the fact the tail rotor departed the aircraft. That was followed by a tail boom strike due to the fact the aircraft became uncontrollable. Both of those aren't common in helicopters.
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In my novice mind, I can’t figure out what happened here. Obviously the tail rotor came off and that caused the end result, but what do you suspect caused the tail rotor to fly off like that?
 
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Ryanb said:
In my novice mind, I can’t figure out what happened here. Obviously the tail rotor came off and that caused the end result, but what do you suspect caused the tail rotor to fly off like that?
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The comments say they hit the power line but it's hard to tell. You can see that they abruptly stopped their descent but I see no wire contact. Could be a number of other reasons for the tail rotor to depart. Could be retaining nut failure, output shaft failure, even loss off the balancing weights. It's hard to tell but it looks like it took the gear box with it, so it might even be some sort of GB failure.

All of that stuff pretty rare though.
 
Velocity173 said:
The comments say they hit the power line but it's hard to tell. You can see that they abruptly stopped their descent but I see no wire contact. Could be a number of other reasons for the tail rotor to depart. Could be retaining nut failure, output shaft failure, even loss off the balancing weights. It's hard to tell but it looks like it took the gear box with it, so it might even be some sort of GB failure.

All of that stuff pretty rare though.
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It didn’t appear that they struck wires and that’s where the partial confusion came from. I’d imagine that something of this sort is rare, but boy, that’s hard to watch..
 
FlyingTiger said:
This thread got me looking at helo crashes. Tail rotor strikes seems like a common problem.

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Agreed, although this situation is rare you are a flying rock and no matter how skillfull you are Newton's law is going to get you!
 
I've never looked under the cowls of an R44 or R22. How does Robinson cool the engine? Shroud and fan? How do engine temps compare to fixed wing applications? I'd think temperatures would be the key to engine longevity and apparently Robinson has it figured out.
 
Stewartb said:
I've never looked under the cowls of an R44 or R22. How does Robinson cool the engine? Shroud and fan? How do engine temps compare to fixed wing applications? I'd think temperatures would be the key to engine longevity and apparently Robinson has it figured out.
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It's been a dozen years or more since I was at the Robinson factory course. To keep their reputation intact they really, really focus on safety. A lot of experiences shared- people walking into tail rotors, wire strikes, accident videos. The one hardest to watch was a guy who just passed his checkride has his wife recording him making a trip around the pattern. He was so excited he forgot to pull carb heat, engine quit, and he apparently panicked and didn't auto. There he is, on final, all but done, and he just pancakes it.

Wire strikes were a big focus. The class is a mixture of newbies and old-timer hot shots. The instructor, Tim, has more experience than everyone there put together and wasn't shy about saying even he isn't immune. He thought he was at one time, but was doing a presentation in another country. Saw the wires for the two days he'd been there. But coming in one landing forgot about one of them and sure enough...

The R22, the small 2-seater, is more fun than you can imagine. But is comparably unstable, so you really have to be on your game. It's like flying a bigger, heavier airplane and then climbing into a 150. Your control inputs have to be more exact. Places you wouldn't hesitate to sit a heavier helicopter are more difficult in an R22. Even the slightest uneven landing spot makes things more difficult in the lighter helicopter.
 
Gerhardt said:
He was so excited he forgot to pull carb heat
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A friend of mine flies the small Robinson helicopters and loves them.. well I brought him up a few weeks ago and he was blown away that I only used carb heat at lower RPM settings.. he indicated that in the Robinson carb ice is a big threat so carb heat is judiciously used
 
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