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.
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
)
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.