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Recent content by Ng2020

  1. Ng2020

    Fatigue justification of a thread bolt

    I am trying to understand your problem description and I can only imagine that you have threads in bearing. Can you not install a longer grip length bolt?
  2. Ng2020

    Engineering designation of critical parts

    Thanks WK, Sw. Your description fits my understanding - I want to avoid a proliferation of critical parts designations, the overhead would just about kill our nascent project. We are a hopeful oem-to-be, manufacuring parts of our own design.
  3. Ng2020

    Engineering designation of critical parts

    Context - I am in a growing startup design/manufacturing environment. No Production Cert. Note: we do fixed wing airplanes, not rotorcraft - an important distinction because of 27.602/29.602. Currently our engineering drawings & process specs do not explicitly identify critical parts, nor do...
  4. Ng2020

    Design Phase Product Integration Management- A new GA Aircraft

    So your investor rep is asking how do you control the programmatic risk of design rework at interfaces. There's no standard for that. Companies that have known this pain have gated review processes (in addition to PDR, CDR) to coordinate maturity across interfaces and also between disciplines...
  5. Ng2020

    Cutout in lower wing skin: How can I hand calc this?

    wing torsional stiffness would be severely impacted, as the aft cell is no longer a closed cell for this bay. this would affect aeroelastic characteristics of the wing involving the torsional mode (divergence, ctrl reversal, flutter analyses need to be revisited). Torque in this bay would be...
  6. Ng2020

    Electric "missile" type UAV/Drone

    When US-persons offer tech advice here on designs with potentially dubious use-cases, does that constitute an export under EAR / ITAR? :)
  7. Ng2020

    Avionics Workshop Training Manual

    For starters https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/FAA-H-8083-31B_Aviation_Maintenance_Technician_Handbook.pdf
  8. Ng2020

    Best Practices - Skin Repair of Trimout Over Circumferential Splice

    10 points to the baggage handler for missing the frames :)
  9. Ng2020

    Plate Bending Problem

    Ok so if it's an internal stowage compartment door, look at ac 25-17. Specifically section 104. It provides guidance as to where dual latching is appropriate.
  10. Ng2020

    Plate Bending Problem

    Is the door large enough that it would be prudent to have 2 latches for redundancy? If you only have 1 latch to play with, then I think the best you could do is determine the centre of pressure for the applied loads then place the latch on the edge adjacent to that.
  11. Ng2020

    Blind rivet tension allowable

    Dca. For ref, in Mccombs supplement to bruhn Appendix A, there is generalised guidance for estimating a rivet's tensile allowable for a specific sheet gage (secondary tensile load applications only) as 20% of the joint shear allowable. Mccombs material was sourced mostly from Chance Vought...
  12. Ng2020

    NAS517 tensile strength

    For conventional airframe fasteners - once you understand the requirements of your specific- a reasonable starting point is the pictorial guides in faa ac43-13b, use this to develop a shortlist of potential fastener specs for your specific application. Since some of the the material in ac43 13...
  13. Ng2020

    Help Required for Free-Free Modal Run

    When effecting your modification on the OEMs FE mesh, did you actually change the topology (add delete elements)? Or did you only change element properties? Was the OEMs model an internal loads model? Was it intended for a modal solution?
  14. Ng2020

    DO-160G Vibration Test for Electric Drives and Gearboxes

    Do-160 is not a 'requirement' but can be best described as an faa-recognised means of demonstrating the suitability of systems & equipment to function properly (if required) or not create a hazard when subject to the intended operating environment. The requirement driving this is 2x.1309a (or...
  15. Ng2020

    safety margins for composites

    Sw: in the context of part 25 composite primary structures, aren't ohc design values used for static strength in order to envelope the effect of bvid, and therefore the static strength check supports the overall 'no detrimental growth' dt philosophy?
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