luv737s Posted January 27, 2015 Report Posted January 27, 2015 Noticed on most takeoffs the RPM never goes above 2550. I know the engine is rated to 2700 RPM, is that normal? Quote
Guest Posted January 27, 2015 Report Posted January 27, 2015 You are correct that it should turn 2700 on takeoff. It could be that your tachometer is not accurate, your propeller governor may need adjustment or your propeller may need adjustment. Clarence Quote
Tmack1 Posted January 27, 2015 Report Posted January 27, 2015 i run 2700 on take off you might want to have that checked has it always done that if it has it should have been caught in an annual Quote
luv737s Posted January 27, 2015 Author Report Posted January 27, 2015 Going into the shop Wed because the nose gear doors are not closing everytime. Russell at Southwest Texas Aviation seems to know his way around Moonys and I will ask him about the RPM. Thanks Quote
luv737s Posted January 27, 2015 Author Report Posted January 27, 2015 Just did the annual in Nov, but the plane had not flown for 4 years!!! I did notice one cylinder is about 68 (#2) but the rest are in the 70s. Quote
jetdriven Posted January 27, 2015 Report Posted January 27, 2015 Put an optical tach on it before adjusting the governor. Often the mechanical tachs read low after a few years. Money procedure says fly it full throttle and full rpm fr 5 minutes then note the rpm then adjust. 3 Quote
Andy95W Posted January 27, 2015 Report Posted January 27, 2015 Russell Stallings is top notch. Definitely able to mention him in the same sentence with Don Maxwell, Paul Loewen, and others. Quote
bonal Posted January 27, 2015 Report Posted January 27, 2015 My mech tach was found to be off by 1000rpm once above 2450 below 2400 it's accurate. Checked with an optical tach. After checking we needed to make an adjustment to the governor to get 2700 in climb. By the way congrats on your 20C and welcome to the Mooney ward. Or is it the Mooney Looney bin...(hey that rhymes) Quote
luv737s Posted January 27, 2015 Author Report Posted January 27, 2015 Thanks for all the great advice. I have a digital Tach but that could be off as well. Will let you all know what happens after Russell gets hold of the plane. Quote
NotarPilot Posted January 27, 2015 Report Posted January 27, 2015 I had the same problem. I felt it was likely the tachometer that was the problem. I sent it to Berkshire Instruments to be recalibrated and whah-la, problem solved. They were very reasonably priced and had a fast turn around time. Quote
RobertGary1 Posted January 27, 2015 Report Posted January 27, 2015 If you have a smart phone there are apps that will measure rpm based on the sound or the flash strobe. Quote
FlyWalt Posted January 27, 2015 Report Posted January 27, 2015 I have a smart phone that I am too dumb to use right :-) Quote
orionflt Posted January 27, 2015 Report Posted January 27, 2015 I had the same situation a number of yrs ago, it was a combination of a number of issues. the first issue was my tach was reading 50 RPM low, the next was the amount of power my engine was producing. when i first bought my plane i was seeing 2650 on take off, a few yrs later I started to notice lower RPM on the first take off of the day and it seemed like i was cruising slower but I couldn't pin down any consistent numbers. during that time i replaced my prop with a new non-AD prop and had the governor rebuilt, my RPMs stayed in the same range 2550-2600 on take off, but i could get 2700 in decent so my governor was working correctly. I was talking to another Mechanic friend and said that I had no evidence but it seemed like my engine wasn't the same power as when I bought it. we discussed the different things to look at (all previously check multiple times) then he said I wonder if your Cam is wearing........the cam had been reground during it's last overhaul and a couple of the lobes were wearing, this reduced the duration and the distance my valves opened reducing the engine performance. the feeling the engine wasn't performing at peak was most prevalent during the first takeoff because the engine was still warming up and hadn't expanded completely, also why later takeoffs seemed better. once I knew what was going on with the engine, I flew it for a few more yrs monitoring the oil and the overall performance. I replaced the cam when I had to tear down my engine due to the prop getting damaged by the hanger door during a storm. once I put everything back together my numbers cam back up to normal. Brian Quote
flyboy0681 Posted January 28, 2015 Report Posted January 28, 2015 Like others here I had the same issue. My A/P had me fire her up while he turned a simple screw which controls the governor. It went from 2550 to 2700 instantly. Since 2550 was all I knew since the time that I bought into the partnership two years earlier, I was amazed at the difference in power during takeoff. Quote
luv737s Posted January 28, 2015 Author Report Posted January 28, 2015 Great advice...I have not thought of the optical device for my smart phone. Going out to do an engine run today and will give it a try. Like I mentioned, the Queen is out of the hanger but she still has a few parasites looming and I will figure it out. She cruises well and close to expected speeds so it may be in my mind, but being new to the mooney I just want it right!! Thanks for all the great advice. Mike Quote
N601RX Posted January 28, 2015 Report Posted January 28, 2015 Be careful, If it is not making 2700 rpm takeoff performance will suffer considerably. One of our former members posted the asking the same question and a few weeks later attempted an intersection takeoff. Unfortunately he isn't a member of any forums or flying anymore. Quote
Marauder Posted January 28, 2015 Report Posted January 28, 2015 Be careful, If it is not making 2700 rpm takeoff performance will suffer considerably. One of our former members posted the asking the same question and a few weeks later attempted an intersection takeoff. Unfortunately he isn't a member of any forums or flying anymore. How far off would be acceptable? I'm seeing between 2,670 and 2,680 consistently on both the EI tach and the JPIS 830. Is it better to be slightly low or slightly high? (2,710 to 2,720) Quote
flyboy0681 Posted January 28, 2015 Report Posted January 28, 2015 Be careful, If it is not making 2700 rpm takeoff performance will suffer considerably. One of our former members posted the asking the same question and a few weeks later attempted an intersection takeoff. Unfortunately he isn't a member of any forums or flying anymore. I assume you are referring to Patrick. I wasn't aware he posed the same question prior to his incident. Quote
N601RX Posted January 28, 2015 Report Posted January 28, 2015 Yes, he had made the same post a while before the accident. Another member had even taken their J model up and did some climb test for comparison. It was fairly close in time, but I don't remember if it was weeks or a couple of months. Its possible he could have resolved it before the accident.. Try a takeoff or go around at 2500 it will make a big difference. I did it accidentally once. It took a few seconds to realize it wasn't climbing normally Quote
flyboy0681 Posted January 28, 2015 Report Posted January 28, 2015 Yes, he had made the same post a while before the accident. Another member had even taken their J model up and did some climb test for comparison. It was fairly close in time, but I don't remember if it was weeks or a couple of months. Its possible he could have resolved it before the accident.. Try a takeoff or go around at 2500 it will make a big difference. I did it accidentally once. It took a few seconds to realize it wasn't climbing normally Since 2550 was all I knew, I guess I always compensated for the lower power. Quote
carusoam Posted January 28, 2015 Report Posted January 28, 2015 To apply some kinda real numbers for thought... The O1 has a 280hp engine (IO550g)with Max RPM set at 2500 rpm... An STC has proven to allow max RPM to be set a 2700 rpm... The new hp rating is 310 hp... Approximately 10% more than the original... Performance change... T/O distance went from 1,200' to 800' at SL.... FF is adjusted to go along with the change. If your engine is not producing full RPM, the effect on T/O distance can be huge. In this case 100rpm is 5% hp difference which equates to 200' T/O distance. Climb rate will be effected in a similar fashion. Measure your RPM, check your FF have your mechanic make the adjustments... Something to consider..., -a- Quote
flyboy0681 Posted January 28, 2015 Report Posted January 28, 2015 To apply some kinda real numbers for thought... The O1 has a 280hp engine (IO550g)with Max RPM set at 2500 rpm... An STC has proven to allow max RPM to be set a 2700 rpm... The new hp rating is 310 hp... Approximately 10% more than the original... Performance change... T/O distance went from 1,200' to 800' at SL.... FF is adjusted to go along with the change. If your engine is not producing full RPM, the effect on T/O distance can be huge. In this case 100rpm is 5% hp difference which equates to 200' T/O distance. Climb rate will be effected in a similar fashion. Something to consider..., -a- After our adjustment, everything was noticeably different, most notably the noise level. Quote
carusoam Posted January 28, 2015 Report Posted January 28, 2015 Pilots that race planes add additional rpm. Noise level goes from bad to hellacious..... Quote
John Pleisse Posted January 28, 2015 Report Posted January 28, 2015 Couple of things. Most people run-up or begin their t/o roll and see only their static rpm (low by about 100rpm), then fail to notice it slightly after lift off when it comes up to full dynamic rpm. My J runs up to only 2600, then produces 2685 shortly after lift off. This is normal. However, 2550 may be a hair low, even for a carbureted bird. Check your full rpm in the air. Also, before you go and spend time with a light, check your vernier adjustment at the governor. Two turns on the rod end or your interior control stop may do it. Quote
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