N6018Q Posted October 21, 2018 Report Share Posted October 21, 2018 My POH has the following warning, "In selecting a cruise rpm, the engine must not be continuously operated for cruise purposes within the range of 2100 to 2350 rpm." My engine was changed from the original IO360A1A to a IO360A1B6. I'm wondering if the original tach redline segment of 2100-2350 still applies. Or maybe its a different range for the A1B6? I realize that the crankshaft counterweights added to my engine may have nothing to do with the reasons for the redline, but I can't find those reasons anywhere that I've searched. Quote Link to comment Share on other sites More sharing options...
Guest Posted October 21, 2018 Report Share Posted October 21, 2018 The original engine/ propeller combination had a limitation. Your new engine/propeller combination may have a limitation depending on the model of propeller and the STC they were installed under. It should be laid out in the PoH supplement for the installation. Clarence Quote Link to comment Share on other sites More sharing options...
carusoam Posted October 22, 2018 Report Share Posted October 22, 2018 Often, the STC will stipulate various changes to the tach grapghics... Getting a tach repainted properly is easy for an instrument shop to get done... Great question, expect to get a proper update from the people that did the work for you... Each engine and prop and probably engine mounts too, get new and different limitations. Don’t expect the old limits to apply, but don’t guess on what the new limits are... Broken welds in the engine mount can result from these vibrations... PP thoughts only, Not a mechanic... Best regards, -a- Quote Link to comment Share on other sites More sharing options...
N6018Q Posted October 22, 2018 Author Report Share Posted October 22, 2018 6 hours ago, carusoam said: Great question, expect to get a proper update from the people that did the work for you... Broken welds in the engine mount can result from these vibrations... -a- And that's my problem, this work was done in 1979. I have all the log books and extensive records, including receipts, etc. for the plane but can find nothing related to this issue in the documentation. Make me think it wasn't addressed, and also worries me because of the "broken welds" or worse possibilities. The plane/engine/prop combination has a little over 1100 hours since installation but I know all that means is that a problem may be imminent. Probably an expensive proposition, but does anyone have any recommendations on someone who can do the engineering on this? Quote Link to comment Share on other sites More sharing options...
carusoam Posted October 22, 2018 Report Share Posted October 22, 2018 Similar to a good PPI... A review of logs and STC documents and POH updates... lining up model and serial numbers of the equipment that has been installed... Somewhere along the way, my 65C got an updated rpm range to avoid... the less than diligent ownership chain complied with the change by putting a sticker on the tach’s glass... Do you have a relationship with your local MSC? Your local mechanic should be pretty handy for this type of paperwork... they have to do AD searches at each annual... Often, a three bladed propellor or other specific prop have been installed to eliminate these tach restrictions... What prop do you have? PP thoughts only, not a mechanic... Best regards, -a- Quote Link to comment Share on other sites More sharing options...
N6018Q Posted October 22, 2018 Author Report Share Posted October 22, 2018 I have the (inspection required) Hartzell HC-C2YK-1B with 7666A-2 blades that, according to Hartzell's website, do have the 2100-2350 rpm limitation. I'm just not sure whether the -A1B6 engine changes that. I will bring it up at the next annual (hopefully at DMax). 1 Quote Link to comment Share on other sites More sharing options...
Bob_Belville Posted October 22, 2018 Report Share Posted October 22, 2018 You or your A&P might get an answer from Hartzell with a phone call. Pretty savvy tech folks there. 3 Quote Link to comment Share on other sites More sharing options...
jaylw314 Posted October 22, 2018 Report Share Posted October 22, 2018 From Hartzell's application guide for the HC-C2YK-1B(F) for the M20E: "With IO-360-A1A, A1B engines: Avoid continuous operation between 2000 and 2350 RPM." 1 Quote Link to comment Share on other sites More sharing options...
Marauder Posted October 22, 2018 Report Share Posted October 22, 2018 I have the (inspection required) Hartzell HC-C2YK-1B with 7666A-2 blades that, according to Hartzell's website, do have the 2100-2350 rpm limitation. I'm just not sure whether the -A1B6 engine changes that. I will bring it up at the next annual (hopefully at DMax). What Freemasm is saying that it is not just the prop but the combination of prop, engine and accessories that drove the creation of the RPM limitations.Any idea why they put another engine type in the plane? Looks like you still have the vintage cowl.Sent from my iPad using Tapatalk Pro Quote Link to comment Share on other sites More sharing options...
N6018Q Posted October 22, 2018 Author Report Share Posted October 22, 2018 12 minutes ago, Marauder said: What Freemasm is saying that it is not just the prop but the combination of prop, engine and accessories that drove the creation of the RPM limitations. Any idea why they put another engine type in the plane? Looks like you still have the vintage cowl. Sent from my iPad using Tapatalk Pro Yes, that "combination" issue is what prompted my question in the first place. Airframe had ~1000 hours when engine was replaced. There is no indication of damage (engine nor airframe) in the logs that prompted the change. The -A1B6 was a 7 hour since factory new engine when installed, maybe the owner just got a really good deal? It does seem that he really took care of the plane until the late '90's (other than the paint ) 1 Quote Link to comment Share on other sites More sharing options...
N6018Q Posted October 22, 2018 Author Report Share Posted October 22, 2018 1 hour ago, Freemasm said: For the subject torsional dynamics, it's not just the critical frequency of the individual components that must be considered (e.g. an individual counterweight, prop blade, etc.). The entire rotating mass must also be analyzed when determining critical frequencies (and thus speeds/rpm to avoid). Have all of your related info available before asking your questions if you want to avoid a lot of back and forth or vague answers. If I recall correctly (doubtful as it's been a long time), this issue is specific to that prop paired with non-counter balanced Lycoming four bangers. Let us know what you find, if you would please. It seems you recalled correctly. As @jaylw314 pointed out, the Hartzell application guide states, "With IO-360-A1A, A1B engines: Avoid continuous operation between 2000 and 2350 RPM." The only difference between the A1A and the A1B is the impulse coupling magnetos. Starting with the A1B6, counterweights were added to the crankshaft. The same section of the Hartzell guide lists the HC-C2YK-1B(F) as acceptable for usage with the A1B6 and A1B6D, but does not list these as needing placards. As suggested above, I called Hartzell tech services and they did confirm that my engine/prop combination does NOT have any sub-2700 rpm limitations. 2 Quote Link to comment Share on other sites More sharing options...
N6018Q Posted October 22, 2018 Author Report Share Posted October 22, 2018 Quote Link to comment Share on other sites More sharing options...
carusoam Posted October 22, 2018 Report Share Posted October 22, 2018 18Q, Thanks for sharing all the details and contacts for your decision. Need a recommendation for repainting the Tach’s face to remove any improper markings? The power of MS is amazing sometimes... Best regards, -a- Quote Link to comment Share on other sites More sharing options...
N6018Q Posted October 22, 2018 Author Report Share Posted October 22, 2018 7 minutes ago, carusoam said: Need a recommendation for repainting the Tach’s face to remove any improper markings? Is that possible on a CB budget? As sad as my paint and interior are, I fully intended 6018Q to be my forever plane. As such, I could ignore that little red line. However, I am in a unique position in that my wife WANTS me to upgrade. So, yes, I could use the recommendation. She is hung up on aesthetics and can't or won't see the value of a mid-time, 150 knot, 1 qt of oil per 20 hour plane that flies straight and level without a functioning AP. Quote Link to comment Share on other sites More sharing options...
jaylw314 Posted October 22, 2018 Report Share Posted October 22, 2018 17 minutes ago, N6018Q said: Is that possible on a CB budget? As sad as my paint and interior are, I fully intended 6018Q to be my forever plane. As such, I could ignore that little red line. However, I am in a unique position in that my wife WANTS me to upgrade. So, yes, I could use the recommendation. She is hung up on aesthetics and can't or won't see the value of a mid-time, 150 knot, 1 qt of oil per 20 hour plane that flies straight and level without a functioning AP. Upgrades? Don't listen to anything @xcrmckenna says! Although honestly, that probably applies to 90% of MS'ers The CB in me would suggest simply an EI digital tach gauge. I'm guessing cheaper than finding someone willing to open up the factory tach... 1 1 Quote Link to comment Share on other sites More sharing options...
carusoam Posted October 22, 2018 Report Share Posted October 22, 2018 Parallax is a real challenge with this method... Might be better to get an EI or other tach if spending dough on this... Some smart tachs even calculate rpm drop during run-up... -a- 2 Quote Link to comment Share on other sites More sharing options...
N6018Q Posted October 22, 2018 Author Report Share Posted October 22, 2018 1 hour ago, jaylw314 said: Upgrades? Don't listen to anything @xcrmckenna says! Although honestly, that probably applies to 90% of MS'ers The CB in me would suggest simply an EI digital tach gauge. I'm guessing cheaper than finding someone willing to open up the factory tach... EI is probably the way to go if and when I sell. I largely ignore the original gauge since I got my JPI 830 installed. Quote Link to comment Share on other sites More sharing options...
Guest Posted October 22, 2018 Report Share Posted October 22, 2018 Here is the Type Certificate for the propeller. It doesn’t appear to have a restriction with your engine and prop combination. Quote Link to comment Share on other sites More sharing options...
carusoam Posted October 23, 2018 Report Share Posted October 23, 2018 Amazing skill sets Doc! MSer, MSCer, Mechanic with excellent writing skills, technical documentation skills, and patience! It is great sharing the web with you! Best regards, -a- Quote Link to comment Share on other sites More sharing options...
jazztheglass Posted October 23, 2018 Report Share Posted October 23, 2018 I called Hartzell and quickly got confirmation that I could avoid the interval with my new props 1 Quote Link to comment Share on other sites More sharing options...
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