Run up question

RobBurson · Post by **RobBurson** » Sun Mar 18, 2007 12:50 pm

Hello everybody: I just got 8:50s on my 2000 M7. I have new brakes. I can’t hold it back on run up. I can hold it at 1700 but no more. I can push harder on the brakes but I read a post here about bending some rod if you push to hard. I think it was an older model than mine if I remember right. Why does Maule like the 2000 rpm run up? Other planes I flown run up at 1700 rpm. Is there any draw back to just doing 1700 rpm run-ups? It also seems there is very little clearance between the caliper and tire. My AP who owns a Maule says it’s normal. I suppose I should by the dual puck brakes from Wup. Cheers…Rob

UP-M5 · Post by **UP-M5** » Sun Mar 18, 2007 6:06 pm

when you install 8.50 tires there are 3 little spacers that need to go in between the wheel and the brake disc. these space the caliper away from the tire 3/16" or so. make sure those were installed.

i just did a full power static run-up on mine yesterday, and the single puck brakes held just fine. are your brake linings brand new? maybe they aren't broken in yet???

RobBurson · Post by **RobBurson** » Sun Mar 18, 2007 7:49 pm

Thanks UP-M5. I'll bet you are right on the brakes not being broke in. They were brand new. I ask the AP about spacers, he didn't think the M7 could use them. I'll call Maule. Kind regards...Rob

maules.com · Post by **maules.com** » Sun Mar 18, 2007 9:50 pm

Your plane is new enough it does'nt have the weak pushrods. Double pucks will give a much better feel and gradation for braking. Best to use a set of 3 spacers between the disc and wheel. Mount the calipers on the front as downward forces make for better braking and if you get an inward rolled tyre, or soft or flat tyre the caliper will not grab the rubber and trip you up. If you make short landings with a load on you will definitely know the difference between single and double puck which have four times the performance and with the thicker disc less brake fade. Don't be conned into mixing single puck 1/4"discs with double calipers as I have seen done.
The runup rpm is suggested by Lycoming I think, there is a lot of information in the Lyc engine operaters handbook.

Kirk · Post by **Kirk** » Mon Mar 19, 2007 7:45 am

I've been trying to find the source with no luck but I read a great article on run-ups a while back that addressed RPM at mag check. I found it rather interesting I'll post the link if I find it.

Anyways, what I got out of that was: Lower than specified RPM at runup will not test ignition well (mags, plugs etc) but instead will be more indicative of fuel distribution.

In other words, if you have an engine that has a cylinder or two that are running much leaner or richer you will get a hefty "mag" drop when you check at a lower RPM since at lower RPM the combustion chamber swirl is more critical.

I found this to be the case with my airplane. The mag check was alwys right up to the 175 RPM limit (O540 J1A5D) until we checked the tach and found it was off 175 RPM. Then I boosted the power up and re-checked the mag drop and VOILA it was much better and was a better check of the ignition system.

E.I. has a great troubleshooting manual that can be downloaded free at: http://www.buy-ei.com/The_Pilots_Manual_by_EI.htm

It's pretty useful whether you have a JPI or EI engine monitor/analyzer

Kirk

a64pilot · Post by **a64pilot** » Tue Mar 20, 2007 4:15 am

You have to burn in your brake linings. They won't break in on their own. As has already been stated the double pucks have much greater stopping power. I think they should last longer as well, not sure because I have always had the double pucks.

Run up question

Run up question

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