M7-235 to M7-260

Mods, approval, 337's, STC's, fun with the Feds.
asa
100+ Posts
Posts: 296
Joined: Sat Dec 22, 2018 1:09 pm
Location: KY+AK
Contact:

Re: M7-235 to M7-260

Post 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:
Image

User avatar
Andy Young
100+ Posts
Posts: 1545
Joined: Wed Oct 05, 2011 7:10 am
Location: Alaska, Antarctica, Colorado, and Others
Contact:

Re: M7-235 to M7-260

Post 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.

User avatar
wtxdragger
100+ Posts
Posts: 243
Joined: Sat Nov 09, 2013 3:46 pm
Location: Iraan,Texas
Contact:

Re: M7-235 to M7-260

Post by wtxdragger »

Mercifully Free from the Ravages of Intelligence
1989 M7-235 N90KD
1975 T210L N1675X
2022 CCK-1865 N922UM

https://www.instagram.com/wtxdragger/

asa
100+ Posts
Posts: 296
Joined: Sat Dec 22, 2018 1:09 pm
Location: KY+AK
Contact:

Re: M7-235 to M7-260

Post by asa »

Andy compared to an io520 185 spinning a 86-88” prop at 2850, your (hypothetical) situation seems like nbd.

User avatar
bobguhr
100+ Posts
Posts: 297
Joined: Tue Jun 08, 2010 4:57 pm
Location: West Milford, New Jersey
Contact:

Re: M7-235 to M7-260

Post 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

User avatar
Andy Young
100+ Posts
Posts: 1545
Joined: Wed Oct 05, 2011 7:10 am
Location: Alaska, Antarctica, Colorado, and Others
Contact:

Re: M7-235 to M7-260

Post 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.

Rezrider
100+ Posts
Posts: 486
Joined: Wed Oct 23, 2013 7:53 am
Location: CO
Contact:

Re: M7-235 to M7-260

Post 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.
1980 M5-235
Four Corners

asa
100+ Posts
Posts: 296
Joined: Sat Dec 22, 2018 1:09 pm
Location: KY+AK
Contact:

Re: M7-235 to M7-260

Post 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

Post Reply

Who is online

Users browsing this forum: No registered users and 6 guests