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PT20J

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Everything posted by PT20J

  1. How many threads are we going to have on this issue? We may set a record!
  2. I believe most instances are from failing to close the latch completely before flight. On the models with an internal latch, it is possible to improperly reset this latch after use which might cause it to open in flight. Also, if the cover is missing it might be possible for something in the baggage compartment to shift and catch the latch.
  3. The 3” extensions affect pedal angle moving the top of the pedals aft. My 1994 M20J has different master cylinders, but it looks looks like the technique I used would work on yours. Leave everything connected. Loosen the jam nut. Then you can rotate the shaft. There is a lot of leverage and I didn’t need to turn it more than a couple of turns. More info here…
  4. Any that have the factory inside handle will open when locked from the outside.
  5. No, but you are probably the only one who will admit it
  6. Someone must make them — It seems pretty common for Cessnas to have one for an avionics master.
  7. The GAD 27 provides power to 14V G3X/EIS during engine start brownout so you probably have to pull both breakers to shut down the G3X. But it shouldn’t have any other effect on the autopilot.
  8. Just remember that those are circuit breaker switches, so you need to either find a different breaker/switch or install breakers with the new switches.
  9. I had something similar initially. When pulling the G3X breaker, the G5 would not pass PFT an would show continuous PFT and PTRIM indications and so the auto pilot would not engage. Updating the software to 9.0 fixed it. You might have the dealer update (or reload if you already have the latest).
  10. The GFC 500 has software in multiple components. The G3X and G5 contain part of the logic, and the servos contain part of the logic. The mode controller is primarily a user interface. So, when you pull the G3X breaker, it shuts down the autopilot because that part of the logic is now gone. You can manually restart the autopilot and it will now use the G5 logic in place of the G3X. You shouldn’t have to do anything with the AP circuit breaker. I don’t recall if the G5 PFT runs after a G3X power down, but if it does you will have to wait for it to complete before the FD or AP will work. Skip
  11. I don’t know. My 1978 M20J had Klixons, and my 1994 M20J has E-T-As.
  12. It’s really a good idea to examine the filter media. Lycoming has a service instruction that describes what to look for. Your friendly A&P may cut it open for you or loan you the tool, but the tool is not expensive. I used to carefully cut them open with a hacksaw which, if you are slow and careful, can be done without contaminating the filter media.
  13. Doesn’t the yaw damper servo go beside the pitch servo on the same bracket that has to be installed for the basic autopilot?
  14. If you are talking about the spark plug, Lycoming uses a special serrated helicoil to make sure it stays in place. There is a special tool to do it correctly. https://www.aircraft-tool.com/shop/detail.aspx?id=4260-18
  15. There are usually some for sale on eBay.
  16. The yaw damper is not supposed to be an automatic rudder trim. It will keep the ball centered to coordinate turns and compensate for minor out of trim conditions. If you are significantly out of trim, as in a climb if you don’t have rudder trim(or have it but don’t use it), the yaw damper may not be able to center the ball. Even if it can, you are putting needless strain on the servo asking it to maintain a constant torque for a prolonged period. Skip
  17. Now that we have some indications by model which are experiencing pitch oscillations, let's see what the total number of Mooney installations is regardless of any issues. Yes, I know this is not a scientific poll. And we may do the earlier models later.
  18. Lets say I apply left rudder. The airplane will bank to the left because the rudder introduces a yaw rate which causes the right wing to have a greater airspeed (and thus more lift) than the left wing. However, the directional stability of the airplane will eventually cause the yaw rate (and thus the rolling moment) to decrease. There will however be a sideslip, and if the airplane has dihedral, the resulting yaw angle will cause a rolling moment to the right. So, the ability to turn the airplane with the rudder is dependent on the interaction between the two moments. Reducing dihedral improves the ability to bank with the rudders, but decreases lateral stability and increases propensity to diverge in a spiral. So, rather than mess with the dihedral, the usual fix is to add a spring interconnect between the ailerons and rudder. Skip
  19. I agree with your analysis -- I did neglect the sign. Thanks for pointing that out. There are several roll effects that can be produced by rudder deflection: Roll due to sideslip (dihedral effect) Roll due to yaw rate (differential airspeed between wings) Rolling moment due to rudder deflection (discussed above) Aileron deflection due to rudder deflection (due to the interconnect springs) Skip
  20. For simplicity, I just lumped all the effects into “torque.” But you are correct that there are several forces at work. However, it is incorrect to say that rudder does not counteract torque. The aerodynamic center of the vertical tail is above the aircraft roll axis and so the force generated by rudder deflection does produce a rolling moment. Skip
  21. If it's the Micky Mouse arrangement on the throttle like on my M20J, it's a pain to get it just where you want it. I went up and set up in the landing configuration and figured out where I wanted the throttle to be positioned when it went off and then marked the throttle shaft with a sharpie. Back on the ground, I could fiddle with the switch adjustment until the switch would close when the throttle it the mark.
  22. I have a small group of aeronautical engineer friends that are kind enough to answer my questions and beat around ideas from time to time. I try not to bug them too often. But Ron always seemed happy to hear from me and answer whatever question I had and gently point out the flaws in my understanding. I will truly miss our interactions which were always so informative and pleasurable. Skip
  23. I think Dutch roll is a Beech thing. My wife and I once flew a Duchess from Palo Alto CA to Santa Fe NM and the ride wasn't great out over the desert southwest. One trick is to recognize that there are two different stability criteria: stick-fixed and stick-free. Stick-free is where the control surfaces can float and that's what we normally experience when we fly. Stick-fixed is when we rigidly hold the controls so that the control surfaces cannot move at all. Stick-fixed stability is generally greater than stick-free because the float is destabilizing. So, in the Duchess, I used both feet to block the rudder pedals so that the rudder could not float and the Dutch roll calmed down considerably. Think of it as a poor man's yaw damper
  24. If it is rigged right, the ball should be centered in cruise and require a bit of left rudder in a dive. It's important to make sure the airplane is rigged correctly and that as much control friction as possible has been eliminated before autopilot installation. I understand that Garmin spent a fair amount of effort on this with each test airplane before installing the autopilot for certification. Installers probably not so much. How many avionics shops are even equipped to check Mooney rigging? Even when new, the Mooney controls have a fair amount of friction. I know everyone thinks the push pull tubes are better than cables because cables can stretch. But, cables run through pulleys with ball bearings. The Mooney aileron tubes run through guide blocks with some grease smeared on them at numerous points through the wings. At high airspeeds, the low pressure on the top of the ailerons causes them to want to float up which puts the tubes on both sides in compression and this flexes them slightly increasing the friction. Roger Hoh flight tested the Predator and told me that it was so bad in that airplane that the stick would stay wherever you put it with very little centering force. Another problem with the push pull tubes is that there are a lot of rod ends, and they develop lost motion over time as they wear. The Mooney elevator control friction is worse than the ailerons. Much of the problem is in the eyeball bearing where the control shaft penetrates the control panel. Mooney has had at least three iterations of the penetration, chrome plated the shaft, and tried various lubricating recommendations. The black nylatron eyeballs currently in use are supposed to be self lubricating and kept dry, presumably to avoid crud buildup. I put new eyeballs in my panel when I had it apart and they had significantly less friction than the ones that I removed that were only 1200 hours old but had been lubricated with who knows what. Even with all this effort there is enough friction to create a measured trim band of about 5 KIAS at 65 KIAS. Skip
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