Cracks in Spinner

[Kenny]

I don't know if this has been discussed before, however, whilst doing the two hundred hourly on my 912s Savannah which is fitted with a four blade Brolga prop and Cummins spinner I noticed several cracks on the spinner, one about 20m long and the other about 10m long.

 

It has always been kept tight with absolutly no movement and is one thing I keep an eye on to make sujre it is tight, however I haven't particularly been looking for cracks during my walk round.At first I thought the cracks were only scratches until further inspection.

 

What adds a bit of urgency to this matter is that I know of two other incidents with the same brand of spinner one of them at the same strip that I fly out of . his spinner was also on a Brolga prop fitted to a Lightwing powered with a Rotax 582.

 

The pilot removed the spinner to see if it was repairable and then flew the plane with the spiggot still attached (this is an alumineum rod aprox 15mm thick and about 160mm long) after landing he noticed that the spiggot was missing and there was a big chip out of his prop.

 

The other incident I know of also involved a Savannah which was a much more serious event where the spinner came off in flight breaking one of the prop blades , the plane was just flyable with only a touch of power and had to make an emergancy landing befor the engine tore away from its mounts

 

I would encourage those with spinners fitted to check them regually for cracks also I will not be fitting another to my Savannah and will have to put up with it looking even more agricultural.

 

 

[Guest Maj Millard]

One of the reasons I don't have a spinner on my Powerfin on the Lightwing !. The prop on an aeroplane is the most stressed item on that aeroplane, subject to at least eight different forces, trying to destroy it. The second most stressed item is the crankshaft. Unfortunatly one is firmly attached to the other. Then you go and attach a flimsy aluminum spinner to them both. The potential for cracks in spinners is well known, especially if any looseness or movement is allowed to develope in the fit. I see cracks in spinners all the time on GA aircraft.

 

The potential for disarster is certainly there if a spinner comes loose and decides to go flying on it's own. You are very lucky indeed if it doesn't do serious blade damage on the way out. Some incidents have shown an even worse-case scenero where the spinner is driven back through the windscreen into the pilots face.

 

one recent incident that comes to mind was with a Tigermoth where the spinner departed then impacted and damaged one of the moveable leading-edge slats on the top wing. Had that slat been damaged enough to stop it coming out as speed slowed for landing, and the other one did, things could have got pretty interesting !....If a particular brand of spinner is showing continuing problems, then the manufacturer must be informed, maybe his product needs to be beefed up a bit to handle what it has to. Checking your spinner installation for any movement prior to flight is a real good idea...............................Maj...