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Erratic Trim Position Indication

T

todehnal

Well Known Member
I've been noticing that my Skyview trim indication is starting to jump around a bit while setting it to the take off position. The trim up and trim down switches are still providing smooth movement of the pushrod and trim/servo assembly, but the indicator bounces around quite a bit, and even fails to move with some small trim adjustments. My guess is that there is a wire wound rheostat inside of the little black trim assembly. I thought about squirting a little contact cleaner in there, but I thought it best to seek a little advice first. Also, I was wondering if this is an isolated case. Thanks for any thoughts.........Tom
 
I have an early model 12 (SN58) and it used to do same thing with trim indicator on the D-180 EFIS. I unplugged and cleaned all the wire connections in the tail for the trim servo using contact cleaner and then CRC 2-26 Multi-Purpose Lubricant / Corrosion Inhibitor. Both can be purchased at Home Depot. Problem solved and trouble-free for last 50 hours or so.
 
Tom, if your sure it's not a bad connection (wht/orn, wht/blue, or wht/grn) and you think it's a problem with wiper in the pot, I don't think you will have any issues using contact cleaner on this. You will have to open up the servo. Here is an overview
45pGJpwAwHUl7jiCufho6cHmOF75azIGB5S9MhpWdZcDCTIqLXyJYYougf48JzFAT-UA3U0LPKFvDLTR2mMDlYfLMt61qsI_Ab-VHjwvSyzaZd3Q-2Vh1xnlYYZ4pMvVSggo7MXeIltDkl5mcrSv2LsYcUKesVkmnBDI7gXvEf0KKCo9ugY8LFVMuZ8MaDDB30fuYcAZ4w-xm374O9RnrPmlxJZUiOp1CxyblOBBtpYJg4-l_-XcHkXGrnB4CCiQlnL_iRp57AARHcsL_XpjEF0Ytb3wey_F15_lV4h5VC_TZ3IgEr7KI8M4po1YDMXnnBzhwRdtMTh8FfMmH0Sq0VJda3olAjfhFmwruY358CK-nWPInT-bL-9jiuGT0BfWEwku4U-YgPH9sSjz83WfjR8SXr9yJPXc0qZUrF3jvzV7kme2-lSRUFRSwuUL9pYMcIeufl4vMvaAsZQtwtAzDM9-HQEJT7uviceGoEetojsnCYSmA_-kgEd4kk8nXCJZit7HSw_NTcpRFfwrqe9RX6oapetiCUD73SlbL-Sik6XPjEfSmM_Cm-u6GqDAuGIDZEfNcSTBpGw-ICLyfMKbiVtqh5w3XVJWWqQbL9hIclsjbM_zSZOvb7GyrRQgIEr3LM39M6nHo6ZxNEYt2j90WDqySdRgit8=w650-no



Here is the pot, that long silver thing with the slot in the middle
LV_mM_tpdzVQdPJUi08sVU27d89V7BQuN1GNULTSnNsZ-zt7yxB6W08vZyyamQdTtjNRCCRBEwBVXqhON3iVlflunBo45R_l3nYz6CPYRmgC-Hr-k54aGUvGdtguJQUgPsLqQaG3SPU3y9Bs1WRyg8W12Gn6gqOeB7wsdlwCdJv5pBsaqPzBfbxTfbJM3_gnKrkmyTn4nEMPHWmwkI7nhkQvzD-TJnXJFLJVdKyB8JRkzAMvbpwln3xi9iocK95qp9fVyp5iCCdA5vbkfowT4HLzzEpnRIMQIElGrA1FLNIAWmCmh2FN1vxVjTZ98aDhF1pTu3vYRtapWkhxfOxGrEoGYXuNAZ44StzxqY9SJeK0g5fWZGPR4LtAq3C6T2JwIQ1OKzP6ZbqW3NdDY3KiLwUrUOuAty4UUGq4_I6yHqt3CVniPew9QfiEVRMa9Qox4s-6gR3XAXgTsjAmw5VGVcTg2MBRVnoP5IpvO1_LWaZah-rgxLMuq6GtIHyhwvqHgrmPQNo10AhRlaNk7ANilOffDB_ei8JrK9HfuXyHgY5m7ct-nhOd2u3krOofzSyk4e7SsX8iA-2gRlXZxvVPmZvHCC5on4c600-k7T57TXtHAKnKZZwBbH-VgybK6uql_BNvNC1XbgWyz548NfHXp1hvleKmJkQ=w650-no



This pot is offered with an optional dust shield, I'm not sure if the one in the servo has one. This could complicate the cleaning.
Here is the data sheet for the pot. The pot lever is modified in this applacation.
2m5kxp4.jpg
 
Last edited:
todehnal said:
I've been noticing that my Skyview trim indication is starting to jump around a bit while setting it to the take off position. The trim up and trim down switches are still providing smooth movement of the pushrod and trim/servo assembly, but the indicator bounces around quite a bit, and even fails to move with some small trim adjustments. My guess is that there is a wire wound rheostat inside of the little black trim assembly. I thought about squirting a little contact cleaner in there, but I thought it best to seek a little advice first. Also, I was wondering if this is an isolated case. Thanks for any thoughts.........Tom
Click to expand...

I had exactly the same problem. Mine turned out to be the connector that connects the airframe harness to the trim motor in the tail. Seems like it should be easy but I had a real hard time making sure that connector was making a good connection. It took me several tries and I ended up removing it from the square mounting hole and zip tying it together and to the bracket.
 
Mmiller, thanks for posting that. I am having the same issue on my older D180 system. I've already replaced the connectors, so I'm thinking I probably need to take the servo apart and clean it out. Good to see that it's not impossible to get apart.
 
Thanks guys. I'll perform a detailed inspection and testing of the wiring first, and if that fails to identify the problem, I will move on the the servo itself. Sounds like the most likely cause may be in the connections back there. I do remember those tiny wires and connections as being tedious to work with.

Thanks again................Tom
 
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