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  1. Tads

    Composite Structures certification requirements

    Hi, The article I read was in the journal: "American Helicopter Society Proceedings", and was titled something like: "Certification overview of the AS350 Ecureuil project" - you should be able to find it electronically through most libraries. Let me know if you can't find...
  2. Tads

    Composite Structures certification requirements

    Thanks very much for the advice Steve, just what I was after. I'll have a good read of your paper, very helpful stuff. Joe
  3. Tads

    Composite Structures certification requirements

    Steve, The question was initially a general one, to try and understand what a reasonable testing program is for primary structure - such as a rotor blade. I have seen a few test programs, and from the guidance in AC 20-107A relies fairly heavily on the experience of the manufacturer. Specific...
  4. Tads

    Using Accelerometers for stability of aircraft.

    Hmmm... not sure what your real question is. All modern navigation systems utilise gyros to measure 3-axis angles and rate of change (turn rates). This flows into most Automatic Heading Reference Systems (AHRS). Once this is known, simple vector mathematics can translate the linear...
  5. Tads

    Rotor-blade CofG

    If you are asking questions like that, Good luck!
  6. Tads

    Leading edge erosion

    Hey, don't use those fixed wing products! Prop and fixed wing leading edge erosion tapes disbond in helicopter applications. Very different environments, and you'll get into a whole bunch of troubles: disbonding, vib, balancing problems, etc... We just use nickel steel erosion strips on the LE...
  7. Tads

    Fastener allowables and Shear-out formula

    Hi, Have a look at Niu's famous textbook for a step by step approach. I've encountered the problem before, and I think I did the four calculations mentioned at the start of the thread and picked the worse case - like any repair. Depending on your engineering system, Niu is pretty much an...
  8. Tads

    Composite Structures certification requirements

    Hi All, Thanks for all the great responses, very useful information. Have looked at FAA Advisory Ciucular (AC 20-107A), and to MIL-HDBK-17. Both have good information for general test program requirements. Jean Alesi - had a search for National Resource Specialist, AIR-103, but couldn't find...
  9. Tads

    Landing Gear Design and Ultimate Load

    Hi, It depends if you are talking fixed/rotary wing, as well as what level of certification you will be seeking. A good start is FAR 25, which is very explicit in undercarriage design requirements (and it's definitely not just a drop test!). An excerpt of the requirements are here: GROUND...
  10. Tads

    Composite Structures certification requirements

    Hi All, I have a quick question in regards to the certification of composite aircraft structures. I'm trying to find more info on certification requirements for structure. FAR 25.603 seems to be a little ambiguous on material selection, and the fatigue section tends to focus more on alloys...
  11. Tads

    Transmisssion Ratings for Helicopter Gearboxes

    When you say rated, I'm assuming you are talking about actual performances? Usually due to the rotation speeds being within a small band, horsepower isn't usually appropriate. Therefore, torque is often quoted for gearbox performances, with a maximum torque limitation placed on the component...
  12. Tads

    Composite Rotorblades

    Also, remember that there is a big difference between design, manufacturing, and certification. Obviously the first place to look for rotor blades is with the aircraft's Original Equipment Manufacturer (OEM), as well as Supplemental Type Certificates (STCs) for other rotor blades with your...
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