Tommy Posted March 16, 2015 Author Report Posted March 16, 2015 Lol. I still don't quite get it! Is it possible to have a step by step description how you adjust the rod end so that the stop screw is the limiting factor not the cable? I was reading this : ""Lengthen the control rod 1/2 turn by loosening the jam nut and turning the rod end bearing 1/2 turn."" What the prop cable cockpit end? Does it need any adjustment as well? Thanks! Quote
Guest Posted March 16, 2015 Report Posted March 16, 2015 Lol. I still don't quite get it! Is it possible to have a step by step description how you adjust the rod end so that the stop screw is the limiting factor not the cable? I was reading this : ""Lengthen the control rod 1/2 turn by loosening the jam nut and turning the rod end bearing 1/2 turn."" What the prop cable cockpit end? Does it need any adjustment as well? Thanks! Go to the prop control in the panel and push it full forward, is there a space between the knob and the panel nut? This is called cushion, all power plant controls should have it. Go to the engine and make sure that the pin on the governor arm is in firm contact with the high RPM stop screw from your earlier picture. If you need to adjust further the typical is 25-30 rpm per revolution. If you need to reset the cushion you have to remove the bolt from the cable end and governor arm, loosen the jamb nut and turn the rod end out on the cable, set the jamb nut and reinstall the bolt. If Australia is like Canada you will need two engineers to sign off the control change. If there is no effect from turning the screw there are other things to check. Aside from the governor it is possible that either the prop fine pitch stop is limiting the engine max rpm, which if you have a McCauley propeller is not field adjustable on a Hartzell it is, or the engine does not have the guts to turn the prop to rated speed. Clarence Quote
cliffy Posted March 17, 2015 Report Posted March 17, 2015 Tommy- Please get the help of a competent A&P to do this job. It is classified as "maintenance" and not "preventive maintenance" that an owner/PP is allowed to do. It does need to be signed off in the log book also by an A&P. 1 Quote
Tommy Posted March 17, 2015 Author Report Posted March 17, 2015 Tommy- Please get the help of a competent A&P to do this job. It is classified as "maintenance" and not "preventive maintenance" that an owner/PP is allowed to do. It does need to be signed off in the log book also by an A&P.My A&P is very competent! I just like to educate myself and take this opportunity to expand my knowledge of aircraft mechanics as I don't have an engineering background. Moreover, my A&P actually welcomes the knowledge that I have learnt on MS and loves the idea of having the owner cross referencing his work! And I would NEVER break any rules and regulation intentionally. Quote
cliffy Posted March 17, 2015 Report Posted March 17, 2015 That is very cool! Anything an owner can learn about the inner workings of his plane is great! The time may come when that info proves valuable, very valuable. My hat is off to you for wanting to learn all you can. Quote
cujet Posted March 22, 2015 Report Posted March 22, 2015 Many aircraft will not reach full RPM while static. Yet, will easily reach 2700RPM at some point on the take off roll or in flight. This is generally normal. Also the prop has a low pitch stop. Preventing the blades from going to a flat pitch. Adjusting this stop to achieve 2700RPM static is sometimes not a good idea. "IF" the prop gov fails, the prop blades will rest on the stop. A low pitch stop improperly adjusted will result in an aircraft that might not fly at 2700RPM. The failure of a prop gov to produce sufficient oil pressure will result in high engine RPM in flight. The pilot then pulls back the throttle to reduce RPM to 2700. Airspeed then bleeds off. At some point, generally around 80Kts, the prop is producing enough thrust at 2700 to keep you aloft. Adjusting the low pitch stop for higher static RPM simply reduces in-flight thrust with a failed gov. Most pilots are fully unaware of what happens when a prop gov fails. Some pilots try to maintain airspeeds too high, and simply fly the aircraft into the ground! Properly adjusted, a prop will produce barely enough thrust to maintain straight and level flight, at max gross, at a fairly low airspeed, max RPM. 1 Quote
Andy95W Posted March 22, 2015 Report Posted March 22, 2015 Many aircraft will not reach full RPM while static. Yet, will easily reach 2700RPM at some point on the take off roll or in flight. This is generally normal. Also the prop has a low pitch stop. Preventing the blades from going to a flat pitch. Adjusting this stop to achieve 2700RPM static is sometimes not a good idea. "IF" the prop gov fails, the prop blades will rest on the stop. A low pitch stop improperly adjusted will result in an aircraft that might not fly at 2700RPM. Nice explanation, never thought that whole thing through until now. Thanks. Quote
Marauder Posted March 22, 2015 Report Posted March 22, 2015 I have been watching this thread with interest. Before installing the electronic tach, I would see 2700 on the mechanical tach. Both the JPI and the EI RPM instruments are reporting 2,670 as my max RPM. How much am I losing in rate of climb if I am truly 30 RPM low? Sent from my iPad using Tapatalk Quote
cujet Posted March 22, 2015 Report Posted March 22, 2015 I have been watching this thread with interest. Before installing the electronic tach, I would see 2700 on the mechanical tach. Both the JPI and the EI RPM instruments are reporting 2,670 as my max RPM. How much am I losing in rate of climb if I am truly 30 RPM low? Sent from my iPad using Tapatalk Very little. It's about 1% down on RPM and well less than 1% down on power. Even so, I prefer to achieve full rated RPM when possible. 1 Quote
carusoam Posted March 23, 2015 Report Posted March 23, 2015 Using numbers from the Standing O... They correspond with CUJet, I believe...? O1= 280hp @ 2500 rpm. Standing O1 = 310hp @ 2700 rpm. 30hp gained over approximately 300hp by increasing 200rpm. 10% more hp over 200 rpm. 1% for each 20rpm. Of course, FF must be increased proportionally with that. These thoughts added to performance... O1 take off distance is about 1200' Standing O1 take off distance is about 800' 400' less for the same 200rpm increase. Misusing linear math the same way to extrapolate the data... A 20 rpm decrease 'could' change the T/O distance by about 40' Stretching the data some more... A 30 rpm decrease could decrease the T/O distance 60'. I don't expect that you could use the linear algebra this way. But, the trend is clearly not in your favor... Climb rates are even less linear in the math department. Where excess power is used to climb. I have yet to experience Excess power! Chris, how did I do? Best regards, -a- Quote
Marauder Posted March 23, 2015 Report Posted March 23, 2015 Using numbers from the Standing O... They correspond with CUJet, I believe...? O1= 280hp @ 2500 rpm. Standing O1 = 310hp @ 2700 rpm. 30hp gained over approximately 300hp by increasing 200rpm. 10% more hp over 200 rpm. 1% for each 20rpm. Of course, FF must be increased proportionally with that. These thoughts added to performance... O1 take off distance is about 1200' Standing O1 take off distance is about 800' 400' less for the same 200rpm increase. Misusing linear math the same way to extrapolate the data... A 20 rpm decrease 'could' change the T/O distance by about 40' Stretching the data some more... A 30 rpm decrease could decrease the T/O distance 60'. I don't expect that you could use the linear algebra this way. But, the trend is clearly not in your favor... Climb rates are even less linear in the math department. Where excess power is used to climb. I have yet to experience Excess power! Chris, how did I do? Best regards, -a- Don't know, feel asleep after reading something about fuel flow I got off a red eye this morning, so I'm still falling asleep reading posts... Quote
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