Engine Misfire at Altitude.

[hharney]

Originally Posted by JimC

Is it possible to get pressurized magnetos on a non-pressurized turbo Skymaster? I took my T337E up to FL180 for the first time yesterday and had bad misfiring, so I went back to 16,000 where it ran well. I'd like to be able to use all the FLs I can, especially eastbound.

Sure, it wouldn’t be too difficult. You’d have to tap into the upper deck pressure line…the pressurized Skymasters have a nipple welded to the steel pressure line that runs between cylinders 1 & 2, then a rubber hose comes from that nipple to a tee fitting, then rubber hoses going to the barb fitting on each mag. You’d also want to add an inline filter (1396-2 from RAM Aircraft) just before the tee fitting to make sure you’re not pumping crud into the mags.
You’d have to remove one plastic cap on each mag and add a barb fitting. Also add a gasket between the ignition harness & the mag. Whelen Bruce at Magneto ER is very familiar with this stuff and could hook someone up with the necessary parts if he was given the mag model #’s.
I’m not sure how to do this legally, but I don’t think the actual work would be that much.

Craig Griswold, Director of Maintenance
Griswold Aviation llc
1243 S Kalamazoo Ave Ste C
Marshall, MI 49068
(269) 213-6746 office
(269) 330-2908 cell