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  1. Hi sir, I am sorry I haven’t responded due to not knowing you responded. I have a happy conclusion to our issue. The problem ended up being multiple LRUs failing at the same time. This is why no box swap or mock up change out helped us narrow it down. We found that we had a bad Acceleration sensor, mode coupler, and mode selector. The acceleration sensor was causing the rising command bars AND a computer flag only on the pilots ADI (odd). The #1 mode selector was also causing a intermittent computer flag. On top of all of that, the pilots mode selector Altitude hold would disengage intermittently causing vertical monitor signal errors. The herk is at Youngstown Air Reserve station. To answer your other questions because you took the time out of your day to write me, our swaps were including supply parts, aircraft parts, parts from other aircraft, and back shop mock ups. This particular plane has had FD109 demons for roughly 20 years (usually involving the #1 side of the system. The altitude hold information does come from the Air Data Controllers, and there is one for each side of flight director. This issue started while I was with the plane in a deployed location early this year after the plane had AC bus issues. The 34GS is basically worthless. I used the WDs (formally known as the 13s) to finally figure this one out. It was especially difficult due to how many parts of flight director receive or input the vertical monitor, and vertical fail signals. I appreciate you looking into TOs, and using all the right verbiage obviously showing you know your stuff. We were on the same track the whole time.
  2. Hi there, Yes, the command bars start floating when Altitude hold is engaged. It happens on both sides (#1 and #2). I wouldn’t consider it an A/P issue, as it happens when FD109 Altitude hold is engaged, whether coupled to A/P or not. I should also mention there is a flashing computer flag when it occurs as well. Considering it happens on both sides when the systems are separated 1 and 2 it has me to believe it is a power issue somehow, it also does it in AC and DC. We checked all LRU’s that feed both sides of flight director and they all operate as advertised. tail: 92-3024
  3. Currently having an issue on a 92 model 2.5 that I haven’t been able to crack. When engaging altitude hold on either side, the horizontal command bars float around 5 degrees up. No LRU swap/r2 has fixed the issue and after shooting wires between ADC’s, flight computers, mode selectors, mode couplers, and yaw damper everything checks as advertised. Also have tried SCNS relays. It does it in all flight director modes. If anyone has come across this problem I would love some help. The issue has been on and off for the last 5 months. thanks everyone
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