Mkruger2021 Posted July 3, 2022 Report Posted July 3, 2022 Hello Community, I fired up the plane after a year of working on her (Pretty Proud fired right up!) and took her out for a run up. I noticed a hard left pull on the aileron. (I kind of remembered that too when I flew her home from Minnesota- previous owner. At the time, I could not figure it out. I did some research to find out that I have what is called a PC wing leveller.....Hehe... question is: 1. is it worth keeping 2. I hope i can get it to work 3. Parts 4. If not, how do i disconnect it so i can fly her correctly while I sort things out. (I don't want to hold the button all the time) I hope you all can help out! Thanks in advance Matt Quote
LANCECASPER Posted July 3, 2022 Report Posted July 3, 2022 https://www.windfield.farm/positive-control https://www.knr-inc.com/shoptalk-articles/25-shoptalk/91-201806-pc-systems Quote
Mooneymite Posted July 3, 2022 Report Posted July 3, 2022 (edited) The PC is a simple, reliable, inexpensive wing leveler. There are many (MANY) threads about troubleshooting and repairing it on Mooneyspace. While PCs are aging and nothing lasts forever, most repairs involve finding and patching vacuum leaks. Be aware that there are several versions and up-grades depending on the year of your Mooney, so make sure any advice on Mooneyspace applies to your specific version. The are red and green pneumatic lines. The direction of your turn will determine which color lines and which servos should be traced to find the leak. Serviceable parts (should you need them) are pretty easy to find since many systems have been removed from Mooneys and Beechcraft for autopilot upgrades. However most repairs can be effected with 3M electrical tape, or Permatex. Edited July 3, 2022 by Mooneymite 1 1 Quote
Shadrach Posted July 3, 2022 Report Posted July 3, 2022 Depends on your goal. If you’re flying a lot of hard IFR, the wing leveler is better than nothing but it’s not an auto pilot. The upshot is that they’re simple, reliable, and easy to maintain. First step is to determine actual symptoms. Taxi the aircraft to an open apron and make 90° turns in each direction. The yoke should bank in the opposite direction of the turn. If the yoke turns slightly in the same direction as the turn, the PC isn’t working and you’re seeing the interconnect between the rudder and ailerons move the yoke. First thing is to determine whether the PC is working, partially working or not working at all. Your heavy wing may just be a rigging issue that you’re mistaking for a PC issue. check the logs to see when the vacuum hoses behind the panel were last replaced. They start to look like Swiss cheese after about six years. Very few mechanics like lying on their back in a Mooney foot well and these hoses often stay in service for years if not decades longer than they should. Also check the hose fittings on the pilot sidewall under the instrument access panel ahead of the windshield. It’s not hard to inadvertently knock a hose off the fitting. Quote
MBDiagMan Posted July 3, 2022 Report Posted July 3, 2022 Some good responses here. I fixed up my PC several years ago after figuring out that the Trutrak for Mooney’s was nothing but smoke and mirrors. I flew from far NorthEast Texas to Galveston last Tuesday. Once I had the trim wheel and turn coordinator trim dialed in, it wasn’t an autopilot, but it was very easy to keep it on heading and altitude with a little nudge every once in a while. It is straight forward and simple to fix and very much worth the trouble IMHO. 1 Quote
David Lloyd Posted July 3, 2022 Report Posted July 3, 2022 In the meanwhile, to disable, pull the button out of the control wheel. Seems like there is just an o-ring that keeps it snug in the hole. Do not lose. This is an early 1965 model with the separate PC gyro mounted in the back radio bay, the only year that did so. Quote
Guest Posted July 4, 2022 Report Posted July 4, 2022 7 hours ago, Mkruger2021 said: Hello Community, I fired up the plane after a year of working on her (Pretty Proud fired right up!) and took her out for a run up. I noticed a hard left pull on the aileron. (I kind of remembered that too when I flew her home from Minnesota- previous owner. At the time, I could not figure it out. I did some research to find out that I have what is called a PC wing leveller.....Hehe... question is: 1. is it worth keeping 2. I hope i can get it to work 3. Parts 4. If not, how do i disconnect it so i can fly her correctly while I sort things out. (I don't want to hold the button all the time) I hope you all can help out! Thanks in advance Matt PM sent to you. Clarence Quote
Mkruger2021 Posted July 4, 2022 Author Report Posted July 4, 2022 Thank You everyone for your comments..I will scour through the threads and advice and get her figured out…Might as well leave her in for awhile. Taking them out of the wings looks like a real pain in the XXX….I hope if that pneumatic gyro in my back radio bay operates as described above. Ill look for leaks and check the hoses on the pilot side and get back to you all…. Matt…. Quote
0TreeLemur Posted July 4, 2022 Report Posted July 4, 2022 2 hours ago, Mkruger2021 said: Thank You everyone for your comments..I will scour through the threads and advice and get her figured out…Might as well leave her in for awhile. Taking them out of the wings looks like a real pain in the XXX….I hope if that pneumatic gyro in my back radio bay operates as described above. Ill look for leaks and check the hoses on the pilot side and get back to you all…. Matt…. Unless you are a wiz at boolean search, I find the best way to search mooneyspace is through google. In the search box type keywords like: "repair pc system site:mooneyspace.com" Google will then search mooneyspace.com for those key words. Several of us here on MS have working 3-axis autopilots in our C, all Brittain. Here's a great article: https://knr-inc.com/shoptalk-articles/25-shoptalk/91-201806-pc-systems Quote
DCarlton Posted July 4, 2022 Report Posted July 4, 2022 You'll find many different opinions about keeping the PC system. I've kept mine going for over 18 years now. I'm a mechanical engineer and appreciate old mechanical systems that don't have any software or data bases. Even flew to Tulsa once to have it overhauled before Brittain closed; mine tracks a DG heading bug. Yes there's lots of information on line and there may be one former Brittain employee (Kevin) still willing to help with troubleshooting over the phone. You may be able to install a panel mounted pneumatic switch to deactivate it too if you don't like pushing the yoke button all the time. I have one of those. Quote
65MooneyPilot Posted July 7, 2022 Report Posted July 7, 2022 Just put a wide rubber band over the yoke switch. That is what people did in the old days. Quote
Shadrach Posted July 7, 2022 Report Posted July 7, 2022 I just remove the button when I want to disable the system for an extended period. Quote
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