May have a “sticky” issue….
1976 Warrior, 1400 SMOH
A new and slight vibration upon reducing power from full or cruise, from 1800 to 1200 RPM.
Definitely there. (not imagination)
… Appeared on decent in circuit at power reduction after a 45 Min. local flight. Recall a couple of similar episodes in the past two months.. like when you “note a change” in the sound or feel of the plane and It clears after a few seconds, you note it and nothing ever concerns you until something happens to make “it all add up” , then you remember if it is related.
Other information…
Recent Annual… All plugs burning well, good colour as are the exhaust ports. Compressions good, 5% spread, low 70’, high 60’s. Engine makes upper band of static RPM with an almost new condition prop. (no extensive dressing or overhauls) Nothing appearing on the EDM data that is noticeable. (JPI 830)
Idle is smooth, as are the upper rpms above 2000. Rarely see the 3rd blade on startup. NO sign of “morning sickness” , runups are normal with expected EGT rise on mag checks, RPM drops on mags and carb heat all normal..
Upon shutdown, hand turning the prop, compression on all cyls feels good and normal on all cylinders .
Switching mags, changing mixture has no effect. Vibration feels like doing a runup with a quartering tailwind, like that small shudder you get with the wind against the back side of the prop disk.
Oil is Areoshell multi weight, changed with filter every 25 hours.. used since 2005 since plane purchase.
It’s early in this… starting checks/tests, but I have been around these forums long enough to know there are some very talented and qualified people here, that have a great deal of experience to offer, and may have actually “been there” before.
Intermittent issues can be bears to track down, so I am posting this early on the process.
Going to do a test , hopefully this will reappear, and will be keeping the power constant enough to get (hopefully) a period of EDM data for a better look.
Suggestions? Or a troubleshootng procedure… first to last?
Cheers!
Cap
1976 Warrior, 1400 SMOH
A new and slight vibration upon reducing power from full or cruise, from 1800 to 1200 RPM.
Definitely there. (not imagination)
… Appeared on decent in circuit at power reduction after a 45 Min. local flight. Recall a couple of similar episodes in the past two months.. like when you “note a change” in the sound or feel of the plane and It clears after a few seconds, you note it and nothing ever concerns you until something happens to make “it all add up” , then you remember if it is related.Other information…
Recent Annual… All plugs burning well, good colour as are the exhaust ports. Compressions good, 5% spread, low 70’, high 60’s. Engine makes upper band of static RPM with an almost new condition prop. (no extensive dressing or overhauls) Nothing appearing on the EDM data that is noticeable. (JPI 830)
Idle is smooth, as are the upper rpms above 2000. Rarely see the 3rd blade on startup. NO sign of “morning sickness” , runups are normal with expected EGT rise on mag checks, RPM drops on mags and carb heat all normal..
Upon shutdown, hand turning the prop, compression on all cyls feels good and normal on all cylinders .
Switching mags, changing mixture has no effect. Vibration feels like doing a runup with a quartering tailwind, like that small shudder you get with the wind against the back side of the prop disk.
Oil is Areoshell multi weight, changed with filter every 25 hours.. used since 2005 since plane purchase.
It’s early in this… starting checks/tests, but I have been around these forums long enough to know there are some very talented and qualified people here, that have a great deal of experience to offer, and may have actually “been there” before.
Intermittent issues can be bears to track down, so I am posting this early on the process.
Going to do a test , hopefully this will reappear, and will be keeping the power constant enough to get (hopefully) a period of EDM data for a better look.
Suggestions? Or a troubleshootng procedure… first to last?
Cheers!
Cap
