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Re: M7-235 to M7-260
Posted: Tue Oct 05, 2021 2:51 pm
by asa
In my search for a shop that can turn around an overhaul in less than 5 months, I called AirPower about Lycoming factory remans.
IO-540-W1A5D Factory Reman is 20-22 weeks (5 months) and $52k. Extends TBO by 200 hours as well and includes roller tappets.
Getting a V4A5 in exchange for W1A5D is same lead time and price.
Exact Quote:
Re: M7-235 to M7-260
Posted: Tue Oct 05, 2021 9:48 pm
by Andy Young
maules.com wrote: ↑Tue Oct 05, 2021 9:10 am
http://www.pponk.com/HTML PAGES/propcalc.html
On this site one can find the table to enter prop length, blade length and temperature, to calculate tip speed. There is also a discussion re mach speeds and performance, altitude changes etc.
Noise limits were not as limiting as they used to be, but with good reason we should attempt to be neighborly especially to the non flyers who live only on the ground.
For fresh certification, there are specific noise limits and ground clearance limits.
Different types of blades produce different reaction so certification is dependent on proving specific props on specific engines/airframe combinations.
Thanks Jeremy,
I couldn’t make that link work (even copying and pasting the whole thing got an error message) but I did find a similar calculator elsewhere. Turns out an 86” prop stays below .92 Mach (where thrust efficiency drops dramatically) only down to -3°c. So maybe that RPM would not be useful in the winter.
Re: M7-235 to M7-260
Posted: Wed Oct 06, 2021 8:26 am
by wtxdragger
Re: M7-235 to M7-260
Posted: Wed Oct 06, 2021 9:43 am
by asa
Andy compared to an io520 185 spinning a 86-88” prop at 2850, your (hypothetical) situation seems like nbd.
Re: M7-235 to M7-260
Posted: Wed Oct 06, 2021 7:56 pm
by bobguhr
I used Victor Aviation and had my O-540J1A5D (235hp 2400rpm) overhauled as an XR Black VII
I’ve put about 400hrs on the overhaul and no problems to date. Very smooth and plenty of power. I run it with a two blade MT prop (213 cm/ 84”) . The MT is 17lbs lighter than the 81” MAC it replaced.
https://www.victor-aviation.com/Black_Editions_XR.php
Re: M7-235 to M7-260
Posted: Wed Oct 06, 2021 9:34 pm
by Andy Young
asa wrote: ↑Wed Oct 06, 2021 9:43 am
Andy compared to an io520 185 spinning a 86-88” prop at 2850, your (hypothetical) situation seems like nbd.
Very good point.
Though I have often suspected that 185s were not getting the most efficient drive with the 88” prop spinning 2850. In fact, my own experience with them (we have one at work) is that if you start out your takeoff run at full rpm, then dial it back just slightly, you can feel it accelerate as the RPMs drop. In normal practice, we pull it all the way back to where it will keep the RPMs below 2350 prior to beginning the takeoff just to reduce the noise, as it rarely needs all the performance.
Re: M7-235 to M7-260
Posted: Fri Oct 08, 2021 8:20 am
by Rezrider
These engine overhaul prices are crazy. That's more than what my plane is worth. I guess I'll sell mine and let someone else figure out the engine overhaul.
300 hours past TBO and still running well.
Re: M7-235 to M7-260
Posted: Fri Oct 08, 2021 2:09 pm
by asa
Rezrider wrote: ↑Fri Oct 08, 2021 8:20 am
These engine overhaul prices are crazy. That's more than what my plane is worth. I guess I'll sell mine and let someone else figure out the engine overhaul.
300 hours past TBO and still running well.
You must not have checked the airplane market in the past couple years… prices are wild