Crashworthiness of small Heli's

[Vfrpilotpb]

Sadly we are reading of another R22 that has crashed with one fatal , also there seems to have been an Enstrom that crashed with three walking away.

I realise it could be said "How long is a piece of string" when talking about small helicopter accidents and the way they react when coming to a rapid halt by meeting the ground possibly at the wrong angle or speed, but just how crashworthy are these small helicopters, do the manufacturere's follow a strict modern code which is monitered and upgraded, or are they building bodies and fittings to some design type from way back in the 50's, 60's or 70's when the standards were pretty low!

Are they tested by dropping from some known height without any form of restraint or are they sledge tested against some static heavy object?


PeterR-B

Vfr

[pilotwolf]

Don't know about the testing but most aviation things seem stuck in the past in the 'small' end of the market..

Think its difficult to compare accidents between types - especially due to the differences in auto...

Reluctant to say much about the accidents as could be seen as speculation... but guess it depends 'how' you get it on the ground...

PW

[NickLappos]

Vfrpilotpb,

The training helos are all older designs, and meet the previous versions of FAR, where the crashworthiness was much less.

In 1965, the aircraft and the non-energy absorbant seats are designed to:

i) Upward--1.5g.
(ii) Forward--4.0g.
(iii) Sideward--2.0g.
(iv) Downward--4.0g

In 1989 it was increased to:
(i) Upward--4g.
(ii) Forward--16g.
(iii) Sideward--8g.
(iv) Downward--20g, after the intended displacement of the seat device.

and they included crash absorbant seats:
(b) Each seat type design or other seating device approved for crew or passenger occupancy during takeoff and landing must successfully complete dynamic tests......(basically a 30 G stroking seat).


In 1994 they added:
[(v) Rearward--1.5g.]

Recall all that wonderful argument about the certification of the EC 225 grandfathering this stuff? This is the same thing, and creates a compelling case to look to new helos instead of older ones. The problem is I don't know of any newly certified training helos! Anyone out there know?


Here is a web site that gives the evolution of the FAR. Paragraph 27.561 is the crash g's and .562 is the seat stroking (the even number is because it was inserted later, where no previous paragraph existed). Just chose Historical FAR from the left column. Look too at .571 flaw tolerance, and perhaps others, all of whch upgraded the safety.

http://www.airweb.faa.gov/Regulatory_and_Guidance_Library/rgFAR.nsf/MainFrame?OpenFrameSet

[Giovanni Cento Nove]

The number of "different" light helicopters in production out there you can count on one hand.

As to "new" ones well.........EC 120 was probably the last "new" light helicopter (Part 27).

Have a read of FAR Part 27 and Part 29 on the FAA site. This will tell you the requirements. EASA CS27 is similar and can be found here (http://www.easa.eu.int/certspecs_en.html).

Then grab a few TCD Sheets. You will find that there are a lot of grandfather clauses etc etc.

Also on the TCDS read the "Certification Basis". It will give you info on the wherefores of what it was certified to and when, for example EC155B:

Model EC 155B and Model EC155B1 FAR 21.29 and FAR 29 Amendment 29-1 through Amendment 29-40 with the following exceptions: - Excluding Amendment 29-38 (Occupant Protection) - Excluding FAR 29.952 introduced at Amendment 29-35 (CRFS) - Excluding FAR 29.562 introduced at Amendment 29-29 - Excluding FAR 29.631 introduced at Amendment 29-40 - FAR 29.561(a), (b), and (d) at Amendment 29-1 - FAR 29.561(c) at Amendment 29-29 - FAR 29.571 at Amendment 29-20 - FAR 29.571 at Amendment 29-28 fatigue evaluation Composites and new mettalics) - FAR 29.785 at Amendment 29-24 - FAR 29.901 at Amendment 29-26 - FAR 29.903 at Amendment 29-31 - FAR’s 29.963, 29.973, and 29.975 at Amendment 29-26 - FAR 29.1305(a)(4)(i) at Amendment 29-16 - FAR 36 Appendix H through the latest amendment 36-20 - Special Condition 29-007-SC for HIRF - Equivalent level of safety findings: FAR 29.723, 29.725, and 29.727 Landing Gear Drop Test FAR 29.807(c) Passenger Emergency Exits; other than side of fuselage FAR 29.173 and 29.175 Static Longitudinal Stability FAR 29, Appendix B Section IV Return to trim characteristics

Bit of light reading for you.

The EC155 which is a growth of the 365 series and all the clauses as to where it doesn't comply are because it's a growth of an older type - hence the grandfather term. The EC145 is the same because it is really a BK117C2.

It is a huge job to build a "new" type to more current regulations. (Edit - Ask Nick Lappos, they definitely have something to crow about in building a "new" large transport category helicopter, well, mostly new anyway :O)

do the manufacturere's follow a strict modern code which is monitered and upgraded, or are they building bodies and fittings to some design type from way back in the 50's, 60's or 70's when the standards were pretty low

When the code is upgraded they are not required to improve the aircraft in some areas and yes they could remain at the standard, mostly, as when they were certified. This why you see manufacturers trying very hard to stay within the original type certificate when offering "improvements". Yet certain requirements may be non negotiable or are covered by a equivalent level of safety determination.

A clean sheet of paper makes them weep. It is no reflection on EC and most manufacturers operate the same in all classes of aircraft. These are just aircraft examples that I have a bit to do with.

Are they tested by dropping from some known height without any form of restraint or are they sledge tested against some static heavy object?

I know the EC135 fuel system and tank was dropped from a great height to demonstrate its crashworthiness as I have seen photographs of the test and there is more emphasis on design in this area in recent times. The 135 is a Part 27 aircraft with bits of 29 thrown in just in case.

They don't really fling the things down track at a large object like they do with cars either. There are more crashworthy seats out there now which are mainly designed for vertical loading. You will find all the data required in the FAR or EASA Certification Specations.

You are right in your assumption - "How long is a piece of string?" Just what is "crashworthy" - I think you will find it is a "relative term", some are better than others.

[NickLappos]

Giovanni,

Good thoughts, especially about the grandfathering, but I disagree that crashworthiness is relative.

The crashworthiness of the older machines is less than the newer ones, and less safe (still acceptable legally, and ethically, just less).

I checked some TCDS and found no light helos that meet the new requirements. (The EC-120 does meet the latest standards, but it is a far cry from the R-22 or the H-300 in cost and complexity.)

[Lu Zuckerman]

To: Vfrpilotpb

I believe the operative word is "Light". Applying crashworthiness standards to a helicopter like an R-22 means an increase in both weight and cost. The reason they sell so many R-22s is because they don't cost very much and since they are so light they are very maneuverable and are responsive to control input.

Application of the latest certification standards to an R-22 would drive the cost of purchase up and make it less desirable as a personal or training aircraft.

As far as making a comparison between the R-22 and the H-269 I think it would be better to be in the 269 in the event of a crash.

:E :E

[Gaseous]

I alluded to this in the TGRR thread.

Some years ago I went through all the accident records of light piston helicopters that I could find world wide to try to work out which type was least likely to kill me. (Yes I know N480DS was a turbine, but 480s weren't common then) I worked out the fatal accident rate per number of reported incidents. I also tried (with limited success) to do an analysis comparing hours flown to fatalities. This was part of the research I put in before I bought an aircraft. The result- Nothing gets close to Enstrom- mainly because no-one has died in one for about 20 years.

Edit (should have found my notes before I wrote that)

Robinson featured at the bottom of my list. It probably doesn't prove anything but proof is hard to find and some smart arse will always pull any stats apart. Sadly I can't find the file where I recorded the results but If I do I'll post it up. It was one of the major factors in my decision to buy an Enstrom.

Since then, a lot more accidents have happened and a lot more pilots have died - mostly in Robinsons and yes I know a lot more hours are flown in them. Food for thought even so.

Since then, no-one has died in an Enstrom. (in UK)

Ive just found some notes.

[Cyclic Hotline]

I would concur with Gaseous, that the Enstrom appears to have a significantly lower fatality rate than most other light helicopters. However it is not without fatal accidents as a quick perusal of the NTSB (http://www.ntsb.gov/ntsb/query.asp) site will prove.

Maybe that is what attracted F. Lee Bailey to purchase the business?

[pilotwolf]

Running similar to the R22 crash thread but statistics... :(

You could say more people died in Ford Escort crashes than in BMW 3 series... (or any other similar car). More miles in one and one is more affordable than the other so (?)bound to be more accidents?

How many Enstrom hours are flown compared to R22 hours? Is there any reliable way of finding out?

PW

[Gaseous]

PW
Real data is hard to find but where it is available (UK for one) it seems that Enstroms have probably accumulated quite a large fleet flight time. A lot of those still about have done thousands of hours. Mine has 2700 hours. They have also been produced for 30 odd years and more than a thousand have been produced. Agreed it is not terribly good data but it is all we can get - unless someone knows better.
There are no really good figures for comparing all the different types but looking over all the AIBB, NTSB et al, it is hard to draw any conclusion other than flying an Enstrom carries a lower risk of fatality than an flying an R22.

R22s fall out of the sky in bits for unexplained reasons (allegedly). They have issues such as mast bumping and carb ice. R22s have had terminal blade problems. Enstroms don't have any of these problems.
Enstroms are easy to auto to the ground. R22s aren't, assuming it hasnt already killed you before you got auto established. Enstroms give you time to think "Duh the engines stopped" before you drop the pole. R22s don't.

It has even been suggested that the chance of retaining control after a wire strike is better than other types as in an Enstrom, the control rods run inside the mast.

8% of reported Enstrom incidents resulted in a fatality
21% of reported Robinson incidents fatal.
(Source AAIB, NTSB, 1969 to present)
This analysis is broad and rough but to some extent nullifies the effect of hours flown and fleet size.

Incidently the BMW/Escort analogy is not necessarily a good one. In the late 1980s I did a similar analysis (fatal and serious accidents out of total reported accidents) on cars and the loser in that survey was the Audi Quattro, presumably because when it hit things it was going faster!

[helicopter-redeye]

For anybody interested, I did a study last year on R44 accidents. At this stage it is restricted to the UK only, but I will extend it to at least the US next time I have a spare few days.

Certainly points to a very low accident rate ralative to other types (esp. in relation to hours flown, there are quite a lot of R44's about in the UK now).

The results are also the basis for my belief that effective supervision and on-going briefing/ debriefing can significantly minimise the accident rate (I can't see the correlation with the annual LPC at the moment, introduced in FY2000).

My gut tells me the worst accident rate in the UK by type is the Gazelle.

[CRAZYBROADSWORD]

About the only usefull thing I can say seeing that most of my flying is in the R22 and just recently we have had a few crashes that have written of machines but thankfully no fatalities the machine does seem to stand up to alot of abuse, the incident near wellsbourne is very sad indeed but if you look at the kind of flying the R22 does namely instructing and the people who fly it the fact that there are not more accidents resulting in injuries or death speaks volumes. I think what we have to remember is that the R22 is not an IFR all weather machine it is a fair weather machine in which the elements need to be given lots of respect. And the new pilots lots of supervision as to how well it crashes it does better than microlights. {apparently}

[rotorboater]

When you are comparing hours of R22's and Enstroms, surely it doesnt matter what the total hours flown by the machines are as most accidents happen within the 1st 200 hours of the pilot hours.
R22's have very few mechanical failures - almost all are down to pilot error and occur within the pilots 1st 200 hours.
There has been no fatality in any UK Enstrom pilots 1st 200 hours (or any more hours for that matter) therefore they are safer QED

[helicopter-redeye]

On the UK register today there are:-

R22 - 237

R44 - 184

Total Robinson all types - 421

Enstrom (all types) - 77


There are more people buying R22 and R44 new adding to the population.

Weight of numbers and the operational cost must be a factor in where accidents occur. Again, though, note the very low R44 accident rate (UK data) compared to R22.

[dusk2dawn]

During crop dusting I totalled a 269 from zero height and zero groundspeed (tailrotor in potatoplant).
I got out without a scratc, soaked in maneb but the chopper was a total write-off.
Crashworthiness ???

[That lights normal!]

There seems to be a “blurring” of the term “crash worthiness”
The likelihood or ease of crashing is not crashworthiness. Ie Enstroms are generally easy to overpitch (sometimes leading to fatal VRS – Sydney early ‘90s). Low RRPM blade stall is easier to achieve in an R22, but the results are the same for all helicopters.
I wouldn’t class the ease of repair after a crash as crashworthiness. A B47T in SE Qld has been rebuilt after a fatal accident.
Crash worthiness is usually associated with occupants surviving an impact. Two main factors come into play here.:-
1 occupant space remaining at “survivable dimensions” the egg shaped H500 is one of the best light helicopters in this regard.
2 Decelerations are kept to a minimum. Most modern designs are far superior in this regard. It has to be said that the R22 is outstanding for it’s size and weight, with lots of people surviving rather horrific impacts. Despite prejudices, you are more likely to survive hitting a wall in a 2004 Volvo than a ’57 Chevy (I’d rather own the Chevy)
TLN:eek:

[Vfrpilotpb]

Thank you all for your input, since posting this thread I have been troubled by the addition of BT's Broadband, and sadly should have found some other company to go with , cos I had to then be off the air for several days and couldn't read the Pprune threads,

However, from my pretty low perch in the PPL(H) world it does seem that even though there are more R22's about , the Enstrom seems to be the one which is most likly able to allow you to carry on breathing, even after a pretty hard knock, being from a pretty organic farming background even though I fly in the R22(plus others), it is rather built like something you could knock up over a couple of weekends in your garage, but when I (from my point of view) look at the Enstrom and the Shweiser(Spell) they are built rather stronger than the R22, with the Brantley also looking like a good solid piece of kit.

But ignoring the Light end what about the mid range Helis, what exactly do they do to get their ticket to ride?

Vfr:ok:

[rotornut]

Take a look at this, if you haven't already:

http://sa.nextwish.org/Video/helocrash.wmv

The Schweizer/Hughes is indeed a tough little beast but it always helps to have a few lessons before you solo. :\

[Vfrpilotpb]

Thank you Rotornut, seen it before but always good to see what will happen if the bird falls off the perch,

Well the new pilot( not qual) nearly got it right, sadly though it seems to me that the guy who was at the controlls didn't get out, but why the concern fo the guy called "Hog" after all he was only looking at things that 20 seconds earlier had been able to work, ( possibly there was a great amount of spilled 100LL)

Vfr

[Gaseous]

Peter, This crash featured on TV program 'Dumber & Dumber'. I know- an authoritive source, however the story is that Hog was the pilot and he was thrown clear, unhurt as the machine began to rotate. He was not wearing a harness. He is a qualified fixed wing pilot and the proud owner of the pile of scrap. I bloody hope the insurance didn't pay out.