Gear horn and Manifold Pressure

[gsxrpilot]

Another question from my EDM-900 install...

Does the gear warning horn have anything to do with manifold pressure, in a 252?  In the C I used to fly, there was a switch at the carb end of the throttle cable. I know on other Mooney models, the switch is on the cockpit side of the throttle cable.

Today after flying the 252 for the first time with the EDM-900, the gear warning horn came on at take-off and stayed on the entire test flight only going off when the gear was extended for landing.  I know that the manifold circuit that runs into the cockpit was disconnected and rerouted for the EDM-900. I'm wondering if that had anything to do with the gear horn issue.

[kortopates]

4 minutes ago, gsxrpilot said:

Another question from my EDM-900 install...

Does the gear warning horn have anything to do with manifold pressure, in a 252?  In the C I used to fly, there was a switch at the carb end of the throttle cable. I know on other Mooney models, the switch is on the cockpit side of the throttle cable.

Today after flying the 252 for the first time with the EDM-900, the gear warning horn came on at take-off and stayed on the entire test flight only going off when the gear was extended for landing.  I know that the manifold circuit that runs into the cockpit was disconnected and rerouted for the EDM-900. I'm wondering if that had anything to do with the gear horn issue.

No, the gear horn is activated by a micro switch on the throttle cable but rather at the cockpit end like some other Mooneys, on this engine it on the engine side like your old C, just right above the MAGs before it attaches to the servo. Sounds like it got loosened up so it not turning off (I assume not closing the switch).

Can't imagine how the EDM 900 install caused that but maybe you'll see why when you look at it. But from memory there is at at least one other hose with UDP air coming through the same grommet in the baffling as the throttle cable, but the hose I recall was just to give UDP air to pressurize the mags.

[Zwaustin]

Could have something to do with the airspeed switch .... I fought this for a while in my K ... but sounds like they messed with the MP circuit from above post so back to installer I guess. 

 

[kortopates]

2 minutes ago, Zwaustin said:

Could have something to do with the airspeed switch .... I fought this for a while in my K ... but sounds like they messed with the MP circuit from above post so back to installer I guess. 

 

The airspeed switch has no associated horn and only serves to prevent the gear from retracting till sufficient airspeed. If it wasn't working, Paul would have had to push the red button override to enable bypassing the airspeed switch and get the gear up. 

Edited January 11, 2017 by kortopates

[Zwaustin]

18 minutes ago, kortopates said:

The airspeed switch has no associated horn and only serves to prevent the gear from retracting till sufficient airspeed. If it wasn't working, Paul would have had to push the red button override to enable bypassing the airspeed switch and get the gear up. 

True, that's what I experienced except yes there was a horn and the gear would come up without the bypass depressed. Turned out to be a bad diode and a wiring problem under the belly. Was a pain in the neck troubleshooting and finally getting it all squared away, obviously that's why it was not functioning per spec. With that being said I have a 930 now and the bill was about 20k installed on a twin and quite a bit gets tampered with thus opening up the door for issues especially if the shop doesn't test fly or conduct a thorough run up after the job is done.