Engine failure in single-engine helicopter

[UnAnswerd]

We all know that when an engine fails in a fixed-wing aircraft, the pilot has a very good chance of surviving, given its ability to glide. But helicopters have a very bad glide ratio. Just wondering if there are any safety measures, procedures, or equipment used in the event of helicopter engine failure.

 

[FracCapt]

The fixed wing pilot needs a good sized area to put the aircraft down safely....the helicopter pilot needs an area just large enough for the aircraft to fit into. I'd much rather have an engine failure in a single engine helicopter than a single engine airplane. The chances of walking away from an autorotation are extremely good...the chances of NOT damaging the helicopter are good, but not great...it all depends on the skill of the pilot and the terrain.

 

[UnAnswerd]

The fixed wing pilot needs a good sized area to put the aircraft down safely....the helicopter pilot needs an area just large enough for the aircraft to fit into. I'd much rather have an engine failure in a single engine helicopter than a single engine airplane. The chances of walking away from an autorotation are extremely good...the chances of NOT damaging the helicopter are good, but not great...it all depends on the skill of the pilot and the terrain.

When you say auto-rotation, does that imply that with total engine failure, the blades will actually spin up in relative wind, and slow the aircraft??? Just wondering how that system works. There are piston-helicopters, and I would have to wonder how the blades can spin without spining the crankshaft. Is there a clutch of some sort? I highly doubt relative-wind could get past engine compression, but maybe I am wrong...

 

[Uncle Sparky]

Say it with me..........In-er-shee-aah........I knew you could! No, when an engine quits on a helicopter, it doesn't just fall out of the sky and leave a cloud with a "poof" logo. Any helicopter has a "magic" altitude(usually 200-300 feet), where it can trade the energy of it's altitude for additional lift. Probably the easiest way for a fixed-wing pilot to imagine it, is to take an airplane and "place" it in the sky at 0kts. What will happen? It will drop out of the sky!! But, in the process, while it is falling the wing will begin to generate lift. While a helicopter is falling through that 200, or better, feet, the rotor is building speed. At the bottom of the dive, the pilot trades rotor speed for lift.

 

[PropsForward]

Autorotation is also how the Gyro planes work. They have a free spinning rotor and a regular airplane type engine with a propeller. As the engine pulls the Gyro forward through the air. the prinicpal of autorotation creates the lift in the rotor allowing it to fly. The rotor is always unpowered and free spinning.

An autorotation in a helicopter is just as managable as a power off glide in an airplane. Just have a shorter glide ratio...

 

[mattpilot]

i hate to break it to you guys ... but statistically, helicopters are way more dangerous and you are more likely to die in an engine failure than in a fixed wing aircraft. Yes, theoretically, if you are Mr Skilled pilot you could bring the helicopter to a perfect landing in an autorotation. But the statistics say more pilots screw up in a helicopter than in an airplane, when it comes to engine failures.

And trust me, a helicopter can be overwhelming!

In an Autorotation, you usually try to maintain best glide speed (~40kts) and come down to about 50 feet that way.... Then you flare the aircraft to reduce speed. Once around 20ft, you slowly start to pull collective (increase AoA on blades) - this will decrease rotor RPM and cushion the landing. If done properly, you walk away without a scratch on the helo.

But comon mistakes are early flaring, early collective application, tail rotor strike (flaring to late & to much), hitting the ground to hard and bouncing back up + subsequently flipping over), etc....

 

[flint4xx]

If you live through a successful autorotation, it was a good auto.

If they can use the aircraft again it was a great auto.

If there was no additional damage from the auto, you will be elevated to Hero status.


http://www.cavalrypilot.com/aerodynamics/autorotation.html

 

[flyifrvfr]

One of the main considerations when an engine quits in a helicopter or an airplane is a suitable landing site. I used to fly with a Police helicopter pilot who was a huey driver in NAM. This pilot was one of the best I have ever flown with. Sadly, while on police patrol, the engine in the Schweitzer 300 failed. The helicopter was at 500 feet and autorotation was established. The pilot was heading for a parking lot of a museam (sic?) when he noticed people walking to their cars. Having no choice, he impacted the parking lots perimeter fence.

Just before impact, the pilot turned the helicopter on his side to save the life of his observer. The crash occurred on November 04, 1998 in Baltimore City. The NTSB report is very interesting for people who put all their faith into an engines manufacturing process. You can also read about the pilot on a website called The Officer Down Memorial Page. Go to reflections, and read first hand what the observer has to say About the pilot Barry Wood.

 

[Birdstrike]

When you say auto-rotation, does that imply that with total engine failure, the blades will actually spin up in relative wind, and slow the aircraft??? Just wondering how that system works. There are piston-helicopters, and I would have to wonder how the blades can spin without spining the crankshaft. Is there a clutch of some sort? I highly doubt relative-wind could get past engine compression, but maybe I am wrong...

Good questions. The rotor blades are not like an unfeathered prop when they spin (as long as they're at zero pitch on the blades). The spining rotor system produces lift during normal power-off descents. With turbines there is a clutch; called a sprag clutch. When the sprag clutch is engaged (automatically) the rotor system is driven by the engine through the transmission. When it is disengaged (also automatically by lowering the collective), the clutch releases the transmission's gear teeth allowing the rotors to freewheel.

As long as the collective is full down (no pitch on the rotors) then the blades will continue to produce lift as the helicopter descends. As was explained, just prior to touchdown the pilot slows the descent, first by applying some aft cyclic in heavy turbines, and then by application of collective (adding pitch to the rotors, producing lift, and arresting the rate of descent to almost zero). Hopefully, you're just touching down as you feed in that last bit of collective.

Like anything else, training and proficiency are key. When regularly practiced, full touchdown autos can become second nature. If they haven't been practiced, then it can be a disaster waiting to happen.