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  1. TugboatEng

    Air India 787 crashes on take off

    I have a feeling there will not have been any alarms. Magnetic trips on breakers are supposed to occur within 1/2 cycle, no? IAC power on the 787 is generated at up to 800 hz. In that case, a hard fault will open circuit breakers in less than 6 ten thousandths of a second? Or does the half...
  2. TugboatEng

    Air India 787 crashes on take off

    We can actually pinpoint the moment the power failed. If you watch this video the 787 landing gear carriage pitches forward and then the belly doors open within one second. In the crash videos we can see the gear pitched forward but no belly doors are open. In that case I would be very...
  3. TugboatEng

    Woodward Easygen vs PLC control system

    The Caterpillar advantage is their local dealer network. Same day service is often available. The Caterpillar disadvantage is that you may need to take advantage of that service. The OEM packages have to be more inclusive of a broader range of requirements so they tend to be more complicated as...
  4. TugboatEng

    Air India 787 crashes on take off

    Isn't the data recorder typically sent to the data recorder manufacturer after such an event? The fact that India hasn't done this reads as if they don't want to know or they're too broke to do it. We know that the gear retraction had initiated, barely. What is the very next button pressed or...
  5. TugboatEng

    Titanium-Stainless Steel Galvanic corrosion

    Dry ice is available and the difference in CoTE between the two materials is substantial. If you can get it cold enough you might be able to use tweezers to extract the pin.
  6. TugboatEng

    Need help sourcing a custom-made Buna O-ring.

    Nobody has mentioned the skill of the installer of the o-ring. Who do you want to pay to do this. In this modern world it doesn't cost more to dovetail an o-ring groove. Include that in your design. It will save you a fortune on comebacks Moulded seals are another option. These work well if...
  7. TugboatEng

    Corrosion on cable trays.

    Zinc plated is the problem. This hardware was likely zinc plated and that's why it's failing. Hot dip galvanizing is a separate process from plating and much more durable. Zinc plating is never acceptable for damp environments. Even automotive manufacturers no longer use zinc plated fasteners...
  8. TugboatEng

    Air Force Diverts Missile Funds To Modify Qatari 747... Money is being taken from Sentinel ICBM program, which is over budget.

    I don't understand. This is what Trump was working against. Not a face mask in sight. I'm not making this political. I only asked if all of the funding for Sentinel was congressionally appropriated or if some of it was discretionary. Isn't that de-escalation?
  9. TugboatEng

    Air Force Diverts Missile Funds To Modify Qatari 747... Money is being taken from Sentinel ICBM program, which is over budget.

    I absolutely understand how a toilet seat ends up costing $6000. I've always said that everybody's understanding of supply and demand is totally backwards. Demand lowers prices! A one off toilet seat that has to go through any type of regulatory approval is going to be exceedingly expensive. I'm...
  10. TugboatEng

    Air Force Diverts Missile Funds To Modify Qatari 747... Money is being taken from Sentinel ICBM program, which is over budget.

    Sure, there is money that is contractually obligated. Is there zero additional funding that may not be? Not even 0.2%?
  11. TugboatEng

    Titanium-Stainless Steel Galvanic corrosion

    Driving corroded pins is risky business. If you strike the pin you risk turning it in to a rivet. Generally, you punch needs to be smaller than the pin diameter to avoiding this but there impossible with such a small pin. There is a significant difference in coefficient of thermal expansion...
  12. TugboatEng

    Corrosion on cable trays.

    You must not use split lock washers or any type of locking washer as it provides a path of water ingress to corroded the connection. If you use no washer, the outside of the connection may appear corroded but the copper ring terminal acts as a gasket and seals the inside. For encapsulating...
  13. TugboatEng

    Air Force Diverts Missile Funds To Modify Qatari 747... Money is being taken from Sentinel ICBM program, which is over budget.

    Is this money congressionally appropriated or part of the Air Force's discretionary budget? Certainly, some of the funding was allocated by Congres but not all of it. The diversion was only 0.2% of the Sentinel cost so far.
  14. TugboatEng

    Air Force Diverts Missile Funds To Modify Qatari 747... Money is being taken from Sentinel ICBM program, which is over budget.

    What specifically are your issues here? Your article says excess money is being utilized and there is no effect on the program. On a side note my grandpa was a QA engineer for the Minuteman 3 program.
  15. TugboatEng

    Use of Gate Valve for Throttling

    And the guides and the stem to disk connection.
  16. TugboatEng

    Air India 787 crashes on take off

    The short doesn't need to be transferred to other busses. If both generators are on and then busses are tied together, both generators are going to be pushing fault currents simultaneously and their protection breakers may trip simultaneously without software intervention. Perhaps generator...
  17. TugboatEng

    Use of Gate Valve for Throttling

    What do you have to lose if the valve fails? -Does failure pose a safety hazard? -Does it pose an environmental hazard? -Is needing to repair or replace the valve an acceptable cost? -Is the loss of control of the process going to result in loss of valuable product? -Are there other components...
  18. TugboatEng

    Need help sourcing a custom-made Buna O-ring.

    The groove needs to have clearance to the o-ring or the o-ring will rupture when compressed. A dovetailed o-ring groove will allow the use of a round o-ring without glue. https://www.sealanddesign.com/technical/o-ring-groove-design/o-ring-groove-design-dovetail/ The challenge is not...
  19. TugboatEng

    Air India 787 crashes on take off

    How is circuit breaker sequencing managed on these types of aircraft? Can a dead short on a load on a distribution panel cause a magnetic trip of an upstream bus-tie breaker? Without sequencing, such a fault may trip both generator circuit breakers simultaneously.
  20. TugboatEng

    SpaceX Starship missions

    I wonder what the PM emission of a SpaceX launch are?

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