Was having a helicopter conversation with someone the other day and the topic of pitch links came up, which led to a discussion about how survivable a broken one would be.

Is it possible to break one and survive the ordeal?

I would imagine that, if you're lucky, the rotor would take the path of least resistance (neutral pitch) and you could maybe sort of compensate with what's left?

I would also imagine that the chances of surviving increase starting very low under a 2-bladed rotor system to high(er) under a 7-bladed rotor system.

Am I correct?

Thanks for any input.

Good Question!!

It's been 30yrs. since I took an extra course in rotorcraft maintenance where I got my A&P.

I'm going to say that losing pitch in one rotorblade will cause asymmetrical lift that would be unrecoverable in a two blade system.  Higher numbers of blades would make recovery possible. 

1983, my dad hit an un-marked guy wire, while doing a power line patrol in a Bell 206B (two bladed rotor system), severing a pitch link.  The aircraft did not remain controllable, they rolled nearly inverted and crashed.   They all survived, but probably only because the power pole was in a lake, and they ended up going into the water.

Dang.  Someone was watching out for your father and his crew that day, and they were watching real closely.

They all got really lucky to be able to swim away from that.  My dad eventually lost his medical due to injuries he received, but everyone survived that day.  My dad didn't remember anything after the initial impact with the wire.  He bent the collective way past the up stop.  

For years, we had a piece of one of the blades at home, the hinge end, about three feet long, with a triangular piece of the windscreen stuck through both sides.  I think after he quit flying it was too painful of a reminder for him, so he got rid of it, (along with his log books, I know he regrets that decision).

Kinds sucks that the guy from the power company sitting in the left seat, had a written warning about that wire, from a previous crew, but he hadn't read it.  The instrument panel broke his leg, so he sued.  I can't remember if it was dismissed, or if my dad won, but he was absolved of any wrong doing.  The FAA didn't even take any certificate action.

Not certain how it relates to full scale, but I've lost pitch links on my rc helis occasionally and it's always a complete loss of control and violent descent. 

I cannot possibly see how losing a PC Link would be survivable. Of course, it was in the response above, for probably the only time in history.

Like this?
https://www.liveleak.com/view?i=1fb_1420758404

I would think with any altitude, or airspeed, you are spot on.  In my strictly fixed wing opinion, the only thing that saved my dad and his passengers, is that they were low altitude, low forward airspeed, and of course over water at the time.

In the above A Star video above, don't they clip the wire with a blade?  So not a pitch link failure?

I posted the A-Star crash video because it's a cable strike.  Not sure if a pitch link broke or if everything broke (more likely)!

No. Get blades out of track a couple of inches and the 1 to 1 vertical increases drastically. Lose all control of a blade and it's over real quick. Hell, just look what happens with ground resonance. Helicopters are not naturally stable. In fact they're barely controllable with everything connected. 

What's crazy is the guy on the ground "helping" moved the cable into the rotors.

I am aware of that video. It is also like the only helicopter to survive that.

There are also people that survive when their parachute doesnt open. We dont say that is a common and survivable experience, however.

We had a broken pitch change link on an Apache in Afghanistan once.  The link was incorrectly handled in the supply chain causing it to be installed on a helicopter when it shouldn't have.  

It broke in flight.  Incredible vibration but the aircraft was otherwise controllable.  They landed immediately with no trouble.  Assorted structural damage to the aircraft from the vibration.  Got it on the gun tape, not sure if the video is on the interweb or not.  

Probably not survivable in a teetering rotor as it would flap until the mast bumped, likely causing the rotor to separate from the aircraft.  

In a rigid or semi-rigid rotor the blade will seek the pitch where aero forces are balanced and stay there.

PC rods... You kinda need those.

On a two blade head like the Huey you would most definitely be phucked. On a Four blade head you "may" be able to make a PL. But the vibrations are going to rattle the fillings out of your teeth.

Yes, that is what I was thinking as well. Fully articulated vs semi rigid might behave differently, but nobody wants to find out the hard way.

On a side note, we had a 60 main transmission that kept having chip lights. Oil samples kept coming back inconclusive. Then all hell broke loose and one of our test pilots just managed to get it on the ground before the box came apart on the inside. It got so hot from the time of the chip lights until he got it on the ground that it melted the paint.

Turns out a tool was left in the box from CCAD during depot repair...

If you watch closely you can see that the component that failed was, as the gentleman mentions in the video, the phase control link or scissor link as many call it. This is a different component than a pitch link. I don't know that a pitch link loss would have been any better or worse, however. I think a major concern, aside from extreme vibrations, would also be rotor RPM. With a blade causing excessive drag, it would be interesting to see if the engine could provide sufficient power to prevent rotor RPM from decaying to the point of rotor stall or not.

As an aside, I'm pretty sure the company developing the helicopter depicted in that video has since folded, and the assets are being sold off. Bit of a bummer, as it looked promising.

In the version of the Huey I fly, it is the only specifically labeled "Land Immediately" emergency, which basically translates into "get on the ground without dying."

Is it survivable?  Under the right conditions...

Really? Fire in flight isn't a "land immediately" sorta deal per the POH? Cause I'd sure consider it to be one, haha!

I always thought Land as Soon as Possible was the most severe you can have, but Apache pilots have one even worse for Hydraulic Failure. Something like "Land Right Fucking Now".

I know of a life flight helicopter locally that flew while on fire.  

He blew both bottles and continued flying to the airport while on fire.

Yeah, most are "Land as Soon as Practical" (i.e. don't break it more and try to find a place maintenance can get to) or "Land as Soon as Possible" (i.e. some damage/injury might happen).
We only have one specifically "Land Immediately," but a couple of the "Land as Soon as Possibles" mention that they may become a "Land Immediately" depending on the specifics.

Worked for a large helicopter company for 21 years as an EMS line pilot,Instructor pilot and Check Airman as well as some offshore oil and gas flying.

We had a pilot ferrying a Bell 206 L1 to an oil and gas base near the coast. He was flying solo at around 1000 feet when he looked down to change frequency and felt what he described as an explosion. The aircraft immediately rolled into almost a 90 degree bank. He said he didn't like that so he slammed the collective full down.

The aircraft immediately righted itself and he established it in an autorotative descent (shut off the engine) that he said was pretty smooth as long as he didn't move the cyclic. Fortunately for the pilot he was over a huge area of open fields and didn't have to turn or try to stretch his glide because that probably wouldn't have worked.

He said the aircraft hopped pretty good when he applied aft cyclic for the initial flare and it jumped like hell when he pulled collective to cushion the landing.

The aircraft touched down pretty hard, spreading the skids and causing the tail boom to crumple and fail just aft of the attachment point but the aircraft remained upright. He hurt his back and was out of work for a month and that was it.

He's one of the few pilots I've heard of that survived hitting a pelican in cruise flight.

What saved him was the fact that he completely lowered the collective immediately. The blade without the PC link was already at flat pitch and lowering the collective put the other blade at flat pitch, basically balancing the rotor system. When he applied aft cyclic in the flare and pulled collective at the bottom, the input was obviously going to one blade so the aircraft jumped around a lot with any control input.

When they got the aircraft back they found so many stretched bolts and popped rivets, they basically cut it up and it went into an industrial sized dumpster.

Best definition I have heard is :

As soon as possible: Quickest landing where everyone survives and the aircraft is undamaged.  
Immediately: Quickest landing where everyone lives, aircraft be damned.  

Yup

What happens after a hyd failure in an AH-64?

The helicopter lands right fucking now.  

Ha, I think I might understand.

Apparently it can be, depending on the rotor system and your response. A 64 lost one in AFG a few years ago and the PC immediately entered an auto and both crewmembers walked away. The way it was explained to me was the auto allowed the free feathering blade to go into plane with the other blades. Conversely, a 64 went down recently at Campbell with the same failure, but the pilot didnt enter an auto, and the blade ended up severing the tail or something ridiculous.

On the latter one, did they survive?

Both crewmembers died in the Campbell crash.

RIP

I have a friend who lost a bolt out of the collective linkage near the rotor mast.
They could stay upright but couldn't reduce pitch to get down. One of the passengers
climbed out on the skid, put the link back together and stuck one of the jaws on a needle nose
leatherman through the hole. He had to stay there and hold the leatherman in the hole
until they got on the ground. He said the temp was around freezing, I don't know how the guy stayed
there.
   They all agreed that they didn't want to do it again.

On 65's we have Land as Soon as Practicable, Land as Soon as Possible, and Land/Ditch Immediately.

Dang, that's insane.  Can't even make something like that up.  Do you have any more details on this one?  My helo pilot buddy would love to hear more about it!  Thanks.