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Ray.R.Doerr(at)sprint.com
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 Posted: Thu May 10, 2007 6:20 am Post subject: Additional item to check at condition inspection time. |
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I'm in the middle of my rolling condition inspection and one of the things I did for the Firewall Forward was to shim the two top engine mount bolts because initially when I did the cowl, I allowed a little too much (5/16") for engine sag. So I thought that after 245 hours on the plane the engine would have sagged enough to just correct the rest of the spinner alignment by shimming the top engine bolts where the engine mount meets the firewall. Two steel washers measuring 1/8" thick on each side did the trick and the spinner matches the top of the cowl perfectly now. Well with this done, I buttoned up the cowl and went for a test flight. Everything was fine for engine run-up and off I went. At 2000 AGL I leveled off and adjusted throttle and prop to 20 squared. While screwing out the prop, at about 1" out it started to get a lot harder to screw out. I kept going because it wasn't too bad yet, but then all of a sudden the engine went from 2300 rpm to something like 1000 or so. I immediately started to screw the prop back in and headed back to the airport.
On my way back I had a few moments to think about this and figured it was the prop linkage hitting the upper air dam. What had happened is the rod-end was up inside the air dam when the prop is fully in, but once you screw it out about 1", it gets to the point where it was hitting the cutout in the air dam, then as I kept screwing it out, it did nothing to the RPM until it finally popped out on the underside of the air dam and this is when the RPM went from 2300 to something really low all at the same time. Once I was back on the ground, I looked at the rod-end bearing at the governor and sure enough, it was hitting the air dam. Since I shimmed the engine by 1/8", it not only dropped the engine at the spinner, but it also moved the engine forward just enough so the prop linkage was hitting the upper air dam. A stupid thing to overlook on my part.
Anyway, I thought I would share this with everyone so they check the clearance of the prop linkage as it goes up through the air dam at there condition inspection. This is important because as the engine sags in time, the clearance you had at first flight may be different now and you may need to remove a little more of the upper dam to have the proper clearance.
Thank You
Ray Doerr
40250
N519RV
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LarryRosen
Joined: 16 Jan 2006
Posts: 415
Location: Medford, NJ
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| Posted: Sat May 12, 2007 6:14 pm Post subject: Additional item to check at condition inspection time. |
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Ray,
How much engine sag did you experience? After how many hours?
Larry
Doerr, Ray R [NTK] wrote:
| Quote: |
I'm in the middle of my rolling condition inspection and one of the things I did for the Firewall Forward was to shim the two top engine mount bolts because initially when I did the cowl, I allowed a little too much (5/16") for engine sag. So I thought that after 245 hours on the plane the engine would have sagged enough to just correct the rest of the spinner alignment by shimming the top engine bolts where the engine mount meets the firewall. Two steel washers measuring 1/8" thick on each side did the trick and the spinner matches the top of the cowl perfectly now. Well with this done, I buttoned up the cowl and went for a test flight. Everything was fine for engine run-up and off I went. At 2000 AGL I leveled off and adjusted throttle and prop to 20 squared. While screwing out the prop, at about 1" out it started to get a lot harder to screw out. I kept going because it wasn't too bad yet, but then all of a sudden the engine went from 2300 rpm to something like 10!
00 or so. I immediately started to screw the prop back in and headed back to the airport.
On my way back I had a few moments to think about this and figured it was the prop linkage hitting the upper air dam. What had happened is the rod-end was up inside the air dam when the prop is fully in, but once you screw it out about 1", it gets to the point where it was hitting the cutout in the air dam, then as I kept screwing it out, it did nothing to the RPM until it finally popped out on the underside of the air dam and this is when the RPM went from 2300 to something really low all at the same time. Once I was back on the ground, I looked at the rod-end bearing at the governor and sure enough, it was hitting the air dam. Since I shimmed the engine by 1/8", it not only dropped the engine at the spinner, but it also moved the engine forward just enough so the prop linkage was hitting the upper air dam. A stupid thing to overlook on my part.
Anyway, I thought I would share this with everyone so they check the clearance of the prop linkage as it goes up through the air dam at there condition inspection. This is important because as the engine sags in time, the clearance you had at first flight may be different now and you may need to remove a little more of the upper dam to have the proper clearance.
Thank You
Ray Doerr
40250
N519RV
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| | - The Matronics RV10-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
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_________________
Larry Rosen
#40356
N205EN (reserved)
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Ray.R.Doerr(at)sprint.com
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| Posted: Mon May 14, 2007 4:43 am Post subject: Additional item to check at condition inspection time. |
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After 250 hours on the plane, it sagged around 1/8" - 3/16".
Thank You
Ray Doerr
40250
N519RV
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