Localizer Glideslope Indicator

[isaacpr7]

   Since I got back I noticed my localizer/glideslope indicator is not working properly when attempting either a VOR/Localizer/ILS approach. I can tune and identify the station and the needle moves momentarily but goes back to center. Can anyone shed some light as to what might be going on and how can I fix it?

[Steve65E-NC]

It would be easier to help your if we knew your general location.  If you are in mid-Atlantic you might try Jim Miller 757-488-7700 at Bay Avionics, Hampton Rhodes Airport, VA

[xftrplt]

That would be Hampton Roads, BTW.

[isaacpr7]

Thanks for the reply guys but I was hoping for a technical answer as to what might be going on before I end up going to an avionics shop. I have had some pretty bad experiences with aviation mechanics so I would like to do research on the issue before I have a shop try and rip me off for something that might be simple.

[carusoam]

Sounds to me like a loose wire.

Have you checked all the connections including to the antenna(e)?

Do you know when it worked last?

To get good experiences with your avionics people, it is helpful when you describe what works and what does not with as much detail as practical...

Best regards,

-a-

[isaacpr7]

Sounds to me like a loose wire.

Have you checked all the connections including to the antenna(e)?

Do you know when it worked last?

To get good experiences with your avionics people, it is helpful when you describe what works and what does not with as much detail as practical...

Best regards,

-a-

Carusoam,

It was working fine before I got deployed and when I returned I picked the aircraft up and noticed it was not working anymore.  As I mentioned before I can tune and identify it. The weird part is that I think the indicator is still receiving some sort of signal beause when I flip the frequency the needle moves left and right slightly and then settles in the center.

[Piloto]

Over half of the avionics intermittent problems are due to contacts. Try removing the NAVCOM from its tray and spraying contact cleaner on the contacts. Try the same on the indicator connector. On the old solid state radios some of the ICs were installed on sockets instead of soldered. The socket contacts oxidize with time creating intermittent problems. The avionics bench guy first approach is to remove the ICs and spray contact cleaner on the sockets and reinstall the ICs. This is common on the old Bendix King radios. On a well designed radio is rare to have a component failure. Most failures are due to connection discontinuity.

 

José 

[isaacpr7]

Over half of the avionics intermittent problems are due to contacts. Try removing the NAVCOM from its tray and spraying contact cleaner on the contacts. Try the same on the indicator connector. On the old solid state radios some of the ICs were installed on sockets instead of soldered. The socket contacts oxidize with time creating intermittent problems. The avionics bench guy first approach is to remove the ICs and spray contact cleaner on the sockets and reinstall the ICs. This is common on the old Bendix King radios. On a well designed radio is rare to have a component failure. Most failures are due to connection discontinuity.

 

José 

 

Thanks a bunch Jose. I will give that a try.

[Skybrd]

This might be due to a electrolic capacitor drying up. Sometimes they will start working again after leaving the radio on. You might try flying the plane for a while and see if it will start working again. My King ADF was not working when I got the plane but after flying it and leaving it on, it fixed itself. When power is first applied it takes a while for it to work right. Older radios are aged especially from electronic capacitors drying up or leaking.

[N601RX]

You didn't mention what kind of radio/indicator you had, but if you can tune the station and hear it clearly, then the antenna/coax should be fine.  If you know anyone who has the same setup, the quickest was would be to slide your radio into their plane and see if the problem goes away.

[N201MKTurbo]

FWIW,

 

The King radios send base band audio to the indicators and all the decoding electronics is in the indicators. The Narco and Garmin radios have the decoding electronics in the radio box and just send the needle signals to the indicator. In either case the receiver and decoder functions are separate.

 

I have fixed four separate king indicators with the same problem. The meter movement coils have yellow tape wrapped around the windings. The adhesive fails after 30 years or so and the end of the tape lifts off and blocks the movement of the needle. I fix them by cutting the end of the tape off with surgical scissors. This takes micro surgery on the instrument and I wouldn't recommend it unless you are very good with such things.

[isaacpr7]

Update:

 

I went flying yesterday for a few hours and the indicator started to work again on its own. Maybe the gremlins living in the back of the instrument panel are on vacation for the holidays. I will still take the connectors off and spray them with contact cleaner as suggested, just to make sure it stays operational. Thank you guys for all the suggestions and merry Christmas