Bendix Scintilla Mag query

[kevkevkel]

I have two Bendix Scintilla mags on my engine - a straight 0-320 originally built in 1957 and sold to Piper.  Engine was rebuilt by Canadian Aero for the vendor from whom I purchased it.

Right mag is S4LN -20 (part #10-51360-29); Left is S4LN-21 (part #10-51360-37).

 Recently when I installing a vacuum pump I loosened the nuts on the right mag to give me a little more room to work and of course damaged the gasket.  I got a new one and installed it after carefully removing and replaced the mag.  Now I read that removal, of mag should only be done by an A&P and that great care is required to avoid dislodging "rubber cushions"!!! Which can apparantly fall down into the accessory case or into the sump.   I never noticed these things and wonder if I missed them.  I'm now reluctant to touch it again unless I really, really, have to, in case (a) I got lucky and didn't disturb them or (b) end up losing them if I open it up again.  If I remove the sump and they're not there then I'm worried I may have to remove the accessory case to find there were none fitted in the first instance.

I also get the impression from some fora that not all engines require these rubber cushions but don't know which - apart from two versions of 0-360 specifically mentioned in dispatches.  I've downloaded the Bendix manual from the Aeronca site and gone through it carefully examining the exploded view and parts list in detail but can find no reference to these rubber cushions.

Can anyone HELP??? 

Regards

Kevin

[BruceHughes]

You might try posting on "canard-aviators@yahoogroups.com"

I have the impression that there are about 10 times as many experts on it.  I know nothing about
magnetos although I have one Slick.

Bruce Hughes   

[MikeD]

Kevin,

What model of O-320 do you have?  I have recently fitted both Bendix mags to my O-320 B3B (Narrow Deck)... no rubber cushions on this model.

Can you remember what the Mag drive gear looked like?  The cushion type is quite large and and only has about 6 large splines  while the other has about 12 splines and is a lot smaller (I'm going from memory here!)

MikeD (U.K.)

[kevkevkel]

Thanks Mike.   According to Lycoming (based on case number) engine started out as a straight 0-320 and was sold to Piper in 1957.  This was before Lycoming introduced suffixes.  That model subsequently became designated as an 0-320 A1A, narrow deck engine.  It was involved in an accident and eventually ended up in the hands of Frank Hoffman in Canada who bought it as a core and whose background I thoroughly checked before buying it - (lecturer in aeronautics in John Abbott university, Montrael; EAA Technical Councellor; Member of Canadas AOPA; representative of the International Council of Aircraft Owner and Pilot Associations (IAOPA) to the International Civil Aviation Organization (ICAO).  He had the engine rebuilt by Canadian Aero to zero tolerances before I bought it from him.   The mounting lugs were modified to fit a Dynafocal mount (this was done before he bought it) and an E2D oil pan was fitted as original was damaged.

 As regards the mag, I'm afraid I just slipped it off as carefully as I could taking as much care as possible to avoid moving any of the gears and replaced it immediately so am afraid I can't remember the detail.  I guess I'll just have to pull it off and have another look.  In any event thanks for the detail.  It is most useful.

Kevin.