Rotax - hand swinging.
 

I have been told it is impossible to hand swing a Rotax 912 because you can not generate enough energy for a start; and that because of this you do not need to treat the prop as always live.

As this goes so against the grain of everything I have ever been taught I thought I would elicit some views from those with rotax experience.

Any views or comments?

I'd agree that hand-swinging pretty much any Rotax is not viable - they need a high speed to get going, have a gearbox which interferes somewhat, and also generally the prop blades are too darned sharp.

The 2-stroke Rotaxes mostly have an optional recoil starter fitted (a bit like a lawnmower's) which solves the problem.

On a 912? If the battery was flat I'd charge it or jump it, if the starter motor was poorly, I'd fix it. I'd not attempt a hand start.

However, I see no reason not to still treat the prop as live - it's basic common sense, which loses you nothing.

G

It doesn't matter what type of prop aircraft your in or which power plant to be honest always treat the prop as live.

I even do when I with the works machine which is a turbine. I try and keep out the prop arc as much as I possibly can.

If you presume every prop is live they can't bite you and more importantly it ingrains keeping yourself safe when sods law is you forget what type of aircraft your dealing with one day.

Your former boss might disagree :)

Air Accidents Investigation: Skyranger 912(2), G-CCXM

Knowing the chap well, he would be the first to admit to having been a complete pillock in that accident. He has, since that occasion, been very open about it, and how stupid he had been - as he is in the quote from him in the report itself.

It probably flavoured my own thinking.

G

I saw a 912 hand-swung a few weeks ago. Started first swing, no problems.

According to my manual the engine requires 300 rpm to start and the prop is geared. There is no special retardation on a magneto for starting. However all that does not preclude an efficient magneto and correct mixture from firing a cylinder.

Jemima is a pusher with wing wires from the deck at the leading edge of the fin. Nothing would induce me to turn over the engine standing inside those wires in any circumstances.

So, it CAN be done!
Where does the story come from that the 4 stroke Rotax are (nearly) impossible to hand crank?

As a 914 owner, this concerns me………


###Ultra Long hauler###

Similar feeling here - and will forward these stories to quite a few people!

Seems a popular subject - it was in the 'hand starting' thread only a couple of weeks ago.

Conrad Beale is widely (and correctly) accepted as the UK Rotax guru. On his course, he says it can be done - so it can be done. Anyone saying anything else is wrong.

Read the AAIB report!

Thanks for the replies - shows the benefit of this forum.
I, and the 400 odd who viewed, now know you can hand swing a Rotax so be careful!

I am still confused.
If you need about 300 RPM to start a (cold) Rotax 4 stroke; how did the gentleman hand-crank his Rotax in the above described incident?

Would a warmed up engine be easier to hand crank?

Cheers,

###Ultra Long Hauler###

Assuming ( :bored: ) 300 RPM is the engine / not prop RPM required to start.

Gear redux ratio in Rotax 912 aircraft I have flown ~2.43, so approx 123RPM required at prop.

Also worth considering is that Rotax throttles are sprung open if the throttle friction is lost! :ok:

Precisely.

Club member chatting to newcomers in the hangar, hand resting nonchalantly on the prop. New Student being introduced to the cockpit, switches off but being shown which key position NEVER to select until ready to start, but did !

Guess what happened !

Fortunately welcoming club member not injured - but he won't touch the prop again.

Murphy is always with us.

Our ALPI / Rotax 912 has a third electronic ignition module, only in circuit when the key is turned to the start position, this retards the ignition on one ignition circuit only, so we start on that one ignition switch. When the starter is released, that starting module is taken out of the system and the circuit reverts to the normal ignition module. It is known as a "Soft Start" system for Rotax engines, and works well, avoiding that teeth shattering jerk if the engine doesn't start first time.

I was told by the dealer that sold me my engine that you could not hand start a 912. I have also watched an owner spend 3 hours trying without success. I do accept that it can be done, but the idea that it is not possible has been around for many years.

Rod1

I saw Brian Milton successfully handswing his Global Flyer flexwing which has a Rotax 912 at the Popham microlight rally many years ago.

Would this be with a warmed up engine only perhaps?

###Ultra Long Hauler###