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Alon Vacuum system

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08 Oct 2023 02:06 #1 by Martin Gibbs
Replied by Martin Gibbs on topic Alon Vacuum system
Hi Gordie
Thanks. I have considered doing the same. My intention is to keep the airplane a day VFR machine .So trying to justify the expense keeps me back from going that route. It would be nice to have reliable attitude and heading information for the occasional night flight and for flying ATC assigned headings though. Pulling the vacuum system may be in my future.

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07 Oct 2023 19:18 #2 by Gordie Meade
Replied by Gordie Meade on topic Alon Vacuum system
I was flying my M-10 along on a beautiful day. I glanced down at my vacuum gauge and watched as it went to zero and the artificial horizon went off about 40 degrees. Had I been IFR or even night flying it would have been a real problem. The fiber gear in the vacuum pump sheared and made all vacuum gauges inop. I depend on my Mooney so I bit the bullet, removed the vacuum system, and installed Garmin G5s. It is probably my best decision. They have back-up batteries that would last about 4 hours if I lost electric power. The batteries are charging while in flight so I never have to do anything to them except check the charge level when I start the airplane.

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11 Sep 2023 01:33 #3 by Martin Gibbs
Replied by Martin Gibbs on topic Alon Vacuum system
Thank you Mike.
Excellent information. It has helped me understand my system much better. I do have a regulator on the inside of the firewall. I think it would take a contortionist to get at it though. I will call AQI and see what they can do for me. I am not opposed to having these instruments overhaul if it isn't too costly. It would be nice to keep the retro look as long as everything is working well.
Thanks again.

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11 Sep 2023 01:22 #4 by Martin Gibbs
Replied by Martin Gibbs on topic Alon Vacuum system
Hi Warren.
Thank you for the info.
I do have a suction gauge. I get about 4.3inhg when the engine is running. Slightly low but the instruments seem to function ok.

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10 Sep 2023 05:34 #5 by Mike Then
Replied by Mike Then on topic Alon Vacuum system
Martin-
Your DG and AI are referred to as "AN" style gauges.  I kept those in my M10.  The only company that I could find to overhaul them was Aircraft Quality Instrument in Kansas (800-842-9938), as they have a source for the bearings.  I found my AI and DG each had a built in filter for the intake, and no single shared intake source.  They are about 1.5 inch round, maybe AQI could help you source replacement filters.  I added a single shared intake (rapco filter) for mine after AQI overhauled my AI.  There should be a regulator in your system, that has a foam garter you want to replace.  Mine was on the firewall inside the cockpit.  I think rebuilt vac pumps are around $350 with an exchange.  Good luck! 
Mike

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05 Sep 2023 22:53 - 05 Sep 2023 23:16 #6 by Warren Hampton
Replied by Warren Hampton on topic Alon Vacuum system
Pic 2 looks to be the Vac pump up side down. that would be under the front case 1. pic without the pump running 5. would be oil pressure line to the oil pressure gauge6. looks to me to be, top oil pressure line at firewall below carb primmer line thru firewall. 4. could be the vacuum to the pump. missing are air filter to vac instruments and a pressure regulator they would be behind the panel inside. 3 & 4 I would have to see where the lines go. the vac pump draws air thru the system that is why the filter and regulator are inside. My Alon had the reg passing thru the firewall. filters have to be replaced every so often 100 hrs.' run to mind. Do you still a Vac gauge? (may say suction on it or Vac) If it is not reading with engine running the pump is dead. I had to replace two pumps one each in my A2 and M20 Mooney. rebuilt pumps are about $1,000. From Aircraft Spruce. or repair kits are available
Last edit: 05 Sep 2023 23:16 by Warren Hampton.
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