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Some background info, I'm trying to think up a device that I can use on an airplane without physically breaking into the aircraft wiring. My problem is I have a plane with gear retraction problems. The gears use inductance proximity sensors, with 28VDC from the control box to the sensor and back to the box, to know when the wheel bogies are in the correct position for retraction and one of them is slow. Is there some sort of circuit using either a clamp style meter, or ring style current detector that I can pass the wire from the two sensors through, and a light will come on when the gear is in the proper position.

Thanks

Something wrong here. You talk about bogies, which imply an aircraft of substantial size with complex gear retraction, yet you ask for a Heath-Robinson or Rube Goldberg solution. Is this a model made by an amateur, or is it a full-size aircraft. Does the OEM know about this problem?

Yes this is a commercial jet. We have been working with the manufacturer but haven’t gotten much help, and the technology of the prox box is not advanced enough to isolate the issue. We know it is an issue with one of the bogies because if the pilot waits about 10 secs after breaking ground to retract the gear there isn’t a problem. And with it being a commercial aircraft, actually breaking into the wiring would require engineering, the FAA, and manufacturers input.

I understand that your requirement is for non-invasive equipment for diagnostic purposes only and not for use on commercial flights.

I am aware of clamp-style devices for measuring ac current and for measuring high values of dc current. However I do not know of any non-invasive way of detecting signal currents such as a few milliamps of 28V dc under aircraft-type conditions.

As a purely temporary measure one might gain approval to replace the appropriate fuse or breaker by an external item which itself is a fuse or breaker and provides means of measuring the signal.

Sorry I can't be of more help.