Non-working glide slope

[Mr. Irrelevant]

Have a friend who I fly with in a Mooney. The glide slope needle is simply staying dead center on approaches. This would be good if the airplane were always on the glide slope. But it's not. The glide slope is not flagged in these cases. He has had a mechanic from a radio shop look at it twice. Using equipment on the ground, everything seems ok. He cleaned all the contacts this past week and still the same issue. Anyone have any suggestions as to why a glide slope needle would check out ok on the ground and then not work in the air? Localizer works fine by the way.

Any feedback is of course appreciated. Thanks.

Mr. I.

 

[xjsparkchaser]

Might be a loose wire on one of the terminals or could also be a vibration induced failure in the nav rec. or indicator. An avionics guy should start checking these things if it's testing fine but always fails in flight.

 

[avbug]

Additionally an antenna problem ranging from an internal problem to a poor ground may be the cause, or an antenna connection. The fault may be in the radio, or in the instrument, or any of the connections or wiring in between. That the aircraft tests on the ground (presumably with a radiated test signal?) indicates that everything has been wired correctly...it can be made to work. You may have an intermittant problem at any number of locations.

You did say that glideslope centers, but with no flag indication?

 

[Mr. Irrelevant]

Thanks for the replies fellas. Yes Av, the glide slope centers but with no flag. Tests out fine on the ground.

Mr. I.

 

[STAL6]

Have the nav receiver bench checked for sensitivity to the glide slope signal.