Hi Ian, As usual, you have raised some interesting points worthy of further discussion. The idea of a small air duct to cool the magneto can do no harm, indeed a similar arrangement should be incorporated into the electronic ignition mod for Dimonas & 109s as we know they have trouble with overheated coils & modules. For legal & safety reasons any such mods should be documented as an "Approved Mod" through the GFA Airworthiness Department to ensure the aircraft's certification is not compromised. Should you wish to create such a mod give me a call & I will guide you through the correct procedure. This is not onerous & while a CAR 35 input is necessary, the design & installation can be engineered at local level & our tame GFA CAR 35 engineer will endorse it if all looks okay. I see no reason why a magneto which was overhauled say 150 hrs ago and which was removed from an engine for reasons other than ignition problems should not be reinstalled on another engine to serve out the balance of its service life. This would of course require accurate tracking of component usage and to achieve this a logbook for the component is a feasible solution. For single aircraft owners it would be quite acceptable to dedicate a page or two of the yellow "component Record" section to individual magneto serial no's,(say half a page per mag) but this method will not work well if the component is likely to be installed on a different aircraft, and for multiple aircraft operators it might be more appropriate to establish separate logbooks for individual components in the same way that we do for propellers. So long as the method used permits accurate tracking of the component's history it would be quite acceptable to me.
Regards John G Viney Senior Technical Officer, Airworthiness GLIDING FEDERATION of AUSTRALIA INC. Please note my new e-mail address as of 23 Feb 2007: [email protected] <blocked::mailto:[email protected]> ------------------------------------------------------ The Gliding Federation of Australia Inc. invites you to visit the web site www.gfa.org.au <blocked::http://www.gfa.org.au/> newcomers to gliding and soaring are invited to visit www.soaring.com.au <blocked::http://www.soaring.com.au/> ------------------------------------------------------------------------ ------------------------------------------- This email transmission may contain confidential or privileged information that is intended only for the individual or entity named in the email address. If you are not the intended recipient, please be aware that any disclosure, copying, distribution or reliance upon the contents of this email is strictly prohibited ________________________________ From: Ian Mc Phee [mailto:[email protected]] Sent: Wednesday, 28 January 2009 8:27 AM To: DOG LIST Cc: Kevin Rodda Subject: [DOG mailing list] slick Mag possible overheating in h36 install Yesterday we had a old (say 1150hr TT slick- I only log engine airtime) which I sent in to Aero Enterprizes with the idea to keep as spare (notice the Swiss on Falke had musical magnetos). Steve when he opened it up said is was one of the worst he has seen even though his ogranization did 500hly on it about 450hrs ago. The trouble is the coil has been getting too hot and was failing under heat gun and Steve then suggested to look again at the installation and consider a small jet of air directed to Mag. Mag is now only core exchange value. The h36 then had the L2000 but now it has S2500. I have already made up aluminium tube to direct air onto the mag hidden down the back. In many aviation installations it is the norm to direct a jet of cool air onto the magnetos and I would consider it a good idea for Dimona especially in AUS. Have a look at a few GA planes. I do know Jabiru require a jet of air and or heat shield at their coil and the Powermate regulator in some installs needs a jet of air onto cooling fins. Electronics/electrical hate excessive heat My interpreting mags is they last the life of the aircraft which in Lycoming would be 1800 to 2100hours but in the case of Limbach it is 1000hrs. As one LAME friend told me as he services a Mag you can tell when they are too old - it shows just like looking at a horses mouth. Personally I would consider (need to pass it by John V) if you keep a log book with a magneto (the Swiss do!!!) then it could be serviced and be used in multiple aircraft. My friend who was chief engineer with King Island Airlines said they would do musical magnetos on Chieftains and would would change a magneto while the passengers sat in terminal for 1 hour. I seem to remember a very small card similar to a parachute repack card was with each magneto which was the mag log book. Anyhow my bottom line is consider air onto magneto like most GA do and maybe even consider doing services say 400hrs as we only have one magneto - it is cheap insurance and the Germans ONLY call for 250hrs on Slick. Ian M
