Parachutes and Helicopters

[relyon]

A point was brought up in the Tiltrotors topic about having emergency parachutes available in the event of an all engines inoperable scenario. I’ll explain my views as to why emergency parachutes in helicopters, VTOL aircraft, and perhaps any aircraft are impractical and can cause far more problems than they potentially solve. Keep in mind this is emergency use only, not where parachute use is part of the mission (airborne drops, HALO, HAHO, etc).

 

Of course, a parachute can be a life saving device if properly used and there are no complications. But there are many things that must go right in order for them to work and numerous things that can go wrong with potentially disasterous consequences. Consider the following:

• Proper training cannot be stressed enough and parachuting should not be considered safe in any sense of the word. I consider a parachute in the hands on an untrained individual the illusion of an option in most cases. Accidents happen far more often and in more ways than one might think.
  
• Emergency parachutes add weight and complexity to any aircraft, and must be maintained like everything else. Parachutes for civilian use are required to be inspected and repacked every 120 days in the US.
  
• An open tailgate the only practical exit that can get out everyone out quickly enough in most cases. A closed tailgate adds the time required opening it and side exits are usually single file.
  
• The movement of passengers may be hindered due to other objects in the cabin or interference between themselves.
  
• The aircraft CG will be continually changing making things difficult for the flight crew at a time when their hands are already full.
  
• Static line deployment requires hooking up the static line to the appropriate point on the airframe prior to exiting and that takes time.
  
• The descent rate in an autorotation or even a glide will be very high and will likely place those exiting in the path of the fuselage, control surfaces, main rotor, tail boom, or tail rotor. That may prove catastrophic for that person and everyone after them.
  
• The parachute will probably need to be deployed immediately upon exit or very soon thereafter depending on the exit altitude, and deployment should be initiated at no less than 500’ AGL.
  
• Deployment problems can and do occur and at a far greater rate than engine failures.
  

Once under a fully deployed parachute there are numerous additional hazards:

• Equipment malfunctions.
  
• Mid-air collisions and aerodynamic interferences.
  
• Landing hazards such as trees, geography, and water in the landing area.
  
• A body under a parachute is far more vulnerable to injury than in an aircraft.
  

I have extensive experience with parachutes and parachuting from both airplanes and helicopters (*), and have been in both simulated and real in-flight emergencies with parachutists and skydivers who knew what to do and there were still numerous problems. That was with people who had parachutes on for intentional use, considerable experience with their use, and in the simulated emergencies knew what was coming and when. Many assume that if they have a parachute their problems are taken care of in an emergency situation and that’s far from the truth.

 

Bob

 

* - The attached picture shows me (first row, second from the right) as part of the US Parachute Team 8-Way Speed Team that competed at the 8th World Parachuting Championships in Canopy Formation held in Imatra, Finland in July of 2000.

 

[gr8shandini]

Good points. Thankfully, I've never had to actually use a chute, but it wasn't until I had to strap one on for a test mission that I really started to think about these things. I imagine most folks are the same way, thinking that merely having a chute on board is a get out of jail card. But I only know of one instance where a crew bailed out of a helo and only one out of two made it. Some of the old timers in my field know of some others instances over the last 40 years, but it's a number you could count on one hand.

 

However, in certain instances, the old maxim "it's better to have it and not need it than need it and not have it" applies, no matter how ridiculous the odds. I think my favorite was on the C-17 and C-5 where in a bail out, they expected us to unstrap, negotiate a flight of stairs or a rope ladder to get to the cargo deck, and then climb a knotted rope against 3 or 4 gs to get to the aft ramp that the loadmaster hopefully opened by the time you got there. But hey, you never know.

 

All in all, though, I agree that for normal flight ops in a helo, you might as well just carry 25 lbs of horseshoes, rabbit's feet, and four-leaved clovers.

[BOATFIXERGUY]

Intereting topic. As far as parachutes in aircraft, the regs say "aircraft" but we all know that if you're piloting a helicopter and usually at or below 500' agl, a parachute is the last thing you want to try. (Tilt rotors can't autorotate and fly much higher...different animal). Military machines are also a different animal and on different missions than civilians. If you have an emergency requiring an auto, why on earth would you want to jump out of the helicopter? A civilian helicopter is designed to safely land in the event of most emergencies. Your rotor is your parachute. Now if you loose the rotor, well...rest in peace.

 

Where would you jump out? I'd like to see someone try to get out of a helicopter even at great altitudes. What's going to happen when you let go of the controls and try to crawl over the cyclic? Will the G-Forces allow it? What attitude will the bird stay in? Flat and level?...doubt it. Even if it did, wouldn't you smash into the rotor? Tail rotor?

 

And yes, the weight of chutes is performance prohibitive. What about the room required. In most birds, that extra inches of equipment is never going to work. I can't imagine adding 4 + inches anywhere around the seat.

[gr8shandini]

You're right. No one is going to hit the silk because of an engine out unless you're in an F-16. Which makes the question "what happens when you let go of the stick" moot. The only reason you'd ever bail is if you've completely lost control of the aircraft, or you're on fire so bad that you're 100% sure that you'll be extra crispy by the time you get down or something important is about to fall off.

 

Here's a link to a microscopic amount of info on the incident I mentioned earlier:

 

http://www.pprune.org/forums/showthread.php?t=52179

 

Less than stellar results to be sure, but a 50% survival rate beats the 0% chance they've had if they rode that one in.

[IFLY]

I try to always wear a chute when flying gliders or hangliders or paragliders...anything else I want it to be part of the aircraft. Never needed one yet but a small jet took the wing off of a glider at about 16,000 feet in Nevada and he walked out after using his chute. I know 5 people that have had to use one and 2 of them were Military Jet pilots, 1 HG, 1 PG, 1 glider. I had never heard of someone successfully jumping from a dead helicopter.

 

Jerry

Edited April 9, 2008 by IFLYEVERYTHING

[JDHelicopterPilot]

It's going to be hard to parachute out of a civilian helicopter. Just due to the fact that there is a big spinning object over head.

 

I too would use one if I was flying a glider, Hanglider or the like. Also I would use one in an plane if I was doing aerobatics.

 

At first I thought this topic was going to be about the parachute system on the SR22 airplanes. That I am for.

[relyon]

Anyone who's read the part of the Tiltrotors thread that mentions parachutes knows I never intended to include the flight crew with those bailing out of a stricken aircraft. This thread was started in direct response to statements made in that topic that passengers will need emergency parachutes if an all engines inoperable sceniario is to be survivable in a tiltrotor.

 

I chose to use the word "Helicopters" in the title and went on to explain why emergency parachutes in helicopters, VTOL aircraft, and perhaps any aircraft are impractical and can cause far more problems than they potentially solve. That seems to have been contorted into the flight crew jumping out of civilian helicopters and I never said or implied that. Quite the opposite, I went to great lengths to say why that wasn't possible and why staying with the machine was a better option.

 

Having said all of that, it's quite possible for a pilot to jump out of a helicopter and avoid all contact including the rotor system(s). The biggest problem by far will be getting out to begin with due to the forces on the door at airspeed and that's where a jettisonable door may be a big plus. Gravity will take over pretty quickly once out and that's when the other problems I listed above start. A whole aircraft emergency parachute system like the SR-22 might be feasable. Something in or above the mast similar to the OH-58 Kiowa could work. There are many potential complications with that as well, the additional mass actually being the least of them.

 

Bob

[Sundowner]

Exactly, the use of parachutes in helicopters is a bit iffy, in most emergences, you can still land safely. The only few that are catastrophic are the loss of the main rotor, total failure of the main gearbox, and uncontrollable fire. Parachutes on helicopters can be used as long as the glide ratio is no less than 1:1 (1:2 is somewhat standard in autorotations), and you can't achieve that without lift, so in helicopters, the only time parachutes would be practical is in case of a fire on board. The thing is - only cases I'm aware off that kind of fire were during take-offs, or at low altitude due to enemy fire (mostly CH-46 thing), so parachutes would not be practical. Although most of the Russian helicopters have them stored in the crew seats, for 27 years use of Mil Mi-14s here, there were not even one event requiring to use them, even though 4 helicopters were lost due to accidents (failed water landing at night, multiple bird strike, and one that hit trees... plus there was one that had to ditch, but there were no injuries) non of them allowed the use of parachutes, ass most accidents were on very low level and give crew no chance to react.

 

Parachute in helicopter is a ballast... Tilt rotor is a different animal.

 

Even if the 'tilt can glide in case of both engine out scenario, than the contact with the ground will be at very high speed, and will be dangerous. Bailing out in that case may be an option. So let me comment on your first post:

 

• Proper training cannot be stressed enough and parachuting should not be considered safe in any sense of the word. I consider a parachute in the hands on an untrained individual the illusion of an option in most cases. Accidents happen far more often and in more ways than one might think.
  

That's true, even with an emergency chute, training is needed, but when having in mind hitting mother earth in an aluminum-titanium, fuel filled box at 150+ kts... I think having only broken legs may be something even untrained people would consider a lower risk

 

• Emergency parachutes add weight and complexity to any aircraft, and must be maintained like everything else. Parachutes for civilian use are required to be inspected and repacked every 120 days in the US.
  

I don't have data for US/UK made emergency chutes (like those in ejection seats), but the Russian made S-4 is rather heavy for its type and weight 33lb, with 20 on board that's 660lb... UK/US made ones should be half of that. And yes every parachute have to be regularly unpacked, checked, dried, and packed... but not all at once ! That would need like what? 1 person per 10 Ospreys to do ? In here there is 13 Mi-14s, thats 58 parachutes on aircrafts, twice more in storage... and that's maintained by 3 people, that are also responsible for ALL other survival and personal flight equipment (helmets, life rafts, life jackets, immersion suits, etc.) and they are not overworked at all!

 

• An open tailgate the only practical exit that can get out everyone out quickly enough in most cases. A closed tailgate adds the time required opening it and side exits are usually single file.
  

I would say 0.3 second is needed to emergency open an ramp... just blow the hinges, let it fly away

 

• The movement of passengers may be hindered due to other objects in the cabin or interference between themselves.
  

Well in that case an emergency egress should be practiced on the mock ups as a standard "boot camp" training, this can be done and won't cost much.

 

• The aircraft CG will be continually changing making things difficult for the flight crew at a time when their hands are already full.
  

The CG change will be only in one axis, I think the crew can menage that, as they are already superhuman at that time - high on adrenaline

 

• Static line deployment requires hooking up the static line to the appropriate point on the airframe prior to exiting and that takes time.
  

That's non-issue. The chute can be attached from the get-go. The chutes are in the seats, the seats are rarely removed, so the line from the chute to the sealing one can be attached when the chute is being mounted in the seat. it will only require something to hide the line so it wont be snagged during normal procedures - some sort of velcro'ed patch will suffice.

 

• The descent rate in an autorotation or even a glide will be very high and will likely place those exiting in the path of the fuselage, control surfaces, main rotor, tail boom, or tail rotor. That may prove catastrophic for that person and everyone after them.
  

As long as the glide ratio is better than 1:1 than it's also a non-issue... when worse, well let the crash worthy seats work their magic.

 

• The parachute will probably need to be deployed immediately upon exit or very soon thereafter depending on the exit altitude, and deployment should be initiated at no less than 500’ AGL.
  

Yes, that's why parachute can't be the only safety device - quite different than Russian engineers think Parachute is only a part of the survival system, used when above certain altitude, airspeed and attitude.

 

• Deployment problems can and do occur and at a far greater rate than engine failures.
  

This may sound strange, but I don't remember any S-4s failures and also any failures of the chutes in modern ejection seats. Those are very reliable and very safe chutes, designed to put man safely on ground, even if he's unconscious! Don't try to compare the emergency chutes that we're talking about with typical paratroopers or civy free fall chute's - those were designed for totally different roles.

[relyon]

This may sound strange, but I don't remember any S-4s failures and also any failures of the chutes in modern ejection seats. Those are very reliable and very safe chutes, designed to put man safely on ground, even if he's unconscious! Don't try to compare the emergency chutes that we're talking about with typical paratroopers or civy free fall chute's - those were designed for totally different roles.

Other than ejection seat systems which I agree are entirely different, I think you're mistaken. In the US, other than the requirement that emergency use parachutes obtain TSO certification, they are identical to intentional use parachutes for a given design, regardless of the application. I suggest you personally log 1000+ jumps from aircraft with the equipment referenced under similar conditions given and I suspect your opinion will change. You may want to note that part of my post that refers to what can happen between leaving the aircraft and arriving safely on the surface. Broken legs are neither small risks nor the only ones faced by far. It gets worse more often than one would like to think.

 

What a parachute is designed for and how it's used in practice are quite often different things. It appears to me that you are speculating about what will happen with a given system by what it was intended for, basing that on your lack of knowledge of failures about one specific type for the most part, and extrapolating that to mean that emergency parachutes are safe, reliable, and usable by relatively untrained individuals.

 

Again, I apologize if I'm mistaken as to what you meant or your personal experience with parachutes and parachuting. I'll not I'm trying not to comment more.

 

Bob

Edited April 14, 2008 by relyon

[Sundowner]

Do I understand you right ? The rescue chute for the Osprey passengers would have to meet the same standards as, lets say T-10D ? If so it may be a problem... the Russian S-4 parachute I'm referring to all the time is a derivate form parachute used in KM-1 Ejection Seat of MiG-21 - that was the first Soviet zero-zero ejection seat. It is designed totally different from the paratrooper chute, what the rigger told me it have very little steering authority, but by itself steers into the wind and have rather low descent rate compared to the combat chutes.

[relyon]

Do I understand you right ? ...

No. An example of that I was referring to is comparing a similarly sized T-10R to a T-10D. Same parachute and same construction where one is certified and the other is not. I'm not that familiar with the S-4. It sounds like an older design, heavy, and used in a "one size fits all" capacity that may or may not be the best solution for a given problem. Not all that different than the R-22 in that respect.

 

Ejection seat parachute systems - which include the seat, harness/container, canopy, instrumentation, control, and deployment sequencing - are an order of magnitude more complicated than the average emergency parachute system and are equally difficult to design. What works well in a low altitude low speed scenario may destroy the parachute and kill or seriously injure the wearer in a high altitude high speed scenario. Ejection seat and emergency parachute system design for helicopter flight crews is even more difficult though some requirements - notably altitude/airspeed capabilities - are fortunately a little easier in some respects.

 

Combat parachutes are different than emergency ones if for no other reason than once deployed a combat parachute is designed to get to the ground as fast as practical and an emergency parachute leans toward being as slow as practical. Total area alone can be the sole difference for a given suspended mass. Steerability is driven by yet other factors with deployment speed being a significant one.

 

Bob