912 912s 914 facts

[dan3111]

Hi there

 

I have always owned two strokes and have got a 912 s for the new project and since have been looking for tips and things about these engine and there is so much to learn on these engines and a lot of traps that can catch us all out . .

 

I just thought I would start a thread on the 912 engines that people can post there tips and things they have seen for there own eyes only (not here say) or bull shit ) . I will start with a few things I have seen for my self on friends 912s.

 

1. That seen two ing coil modules on the same engine give up (one probably stop working before the other just wasn't,t notice until second one stop working ) about 2006 engine with 200 plus hours . The engine was hard the start had to turn over many many times when started run ok but , had weak spark . The fix was two new soft start modules . May be start engine on a different coil each time in stead of both to help pick up a crock module .

 

2. I have seen a 912s with slipper clutch stripped down after it,s TBO had a bend in the crank shaft it had a wood prop strike not long before the strip down . There were rub mark in the cases where the bend crank had been floating around . May by you might get away with a prop strike at idle that,s about it .

 

3 I have seen two seats of carby rubbers look good on the outside but separated from backing plate on the inside real trap to reck your days flying .

 

Cheers

 

 

[Guest Maj Millard]

Hi there Dan3111, Good subject and I'll refer you to my recent post " Rotax 912 failure modes..."....I got a few responses but nothing out of the norm, and I'll do a wrap-up on that one when I get time.

 

On your three points I would offer the following..........

 

Failure of both IGN boxes:........................Please see a recent post on this subject, and my reply. the Rotax IGN boxes are very reliably normally and have a good no-failure history now. the new 'soft-start' boxes are even better and give a cleaner start.

 

Gearbox damage:.......................After any prop-strike either at power or idle the gearbox is assumed to have been damaged, and needs to be removed for inspection. This is a Rotax recommendation.

 

Carb-mount rubbers:...............A known and real problem. Rotax has issued several Service Bulletins on this one, as to how to adequetly inspect them inside and out, and the correct methods of mounting and securing the carbs to eliminate movement. I have seen a good set ruined fairly quickly after being sprayed with Inox. possibly something in Inox that rubbers doesn't like ?. I personally am on my third set, and have another set on order as we speak. I do a lot of flying, and have just turned 700 hrs on my 912uls. The rubbers suffer from overtightening of the clamps, which is why they put the little 7ml bushes on them to eliminate that problem. They have to be well inspected often, inside and out, and can go pretty quickly when they go. General thinking atm is to replace them with new ones every 200-250 hrs, or whenever any deteriation is noticed. When they do crack they tend to 'extrude' from under the clamp, usually at the top. I inspect mine now every preflight as it's easy for me to pop off my top cowl.

 

Positive imput is always good !..............................Cheers Maj...