3 blade prop

[Keith W]

Noticed a gazelle for sale on the RA website with a 3 blade bolly prop,is it legal to fit a 3 blade prop to a gazelle.

 

 

[Riley]

Noticed a gazelle for sale on the RA website with a 3 blade bolly prop,is it legal to fit a 3 blade prop to a gazelle.

I believe you can pretty much put any prop you want on a Gazelle and take pictures and go surreptitiously flying but (unless it's 19 rego-ed) don't plan to be included in any RAA paperwork , insurance claim, CASA ramp check, etc etc, unless it's wearing a two blade Allsize wooden club. The fact that the Bolly 3 blade Optima is a much superior propellor in all respects is of little interest to the helpful people at CASA . Maj Millar is barracking for RAA to 'front' CASA with the ridiculous 'traditional' propellor situation that we're locked into so if you're in his bailiwick make sure you and your mates cast your votes in his direction in the Sept elections.

 

 

[Keith W]

I believe you can pretty much put any prop you want on a Gazelle and take pictures and go surreptitiously flying but (unless it's 19 rego-ed) don't plan to be included in any RAA paperwork , insurance claim, CASA ramp check, etc etc, unless it's wearing a two blade Allsize wooden club. The fact that the Bolly 3 blade Optima is a much superior propellor in all respects is of little interest to the helpful people at CASA . Maj Millar is barracking for RAA to 'front' CASA with the ridiculous 'traditional' propellor situation that we're locked into so if you're in his bailiwick make sure you and your mates cast your votes in his direction in the Sept elections.

[Keith W]

Thanks Riley I thought that was the case, seems pretty ridiculous when everybody I have spoken to that's tried the 3blade on the gazelle says it makes them a much better aircraft.

 

 

[Neil_S]

Thanks Riley I thought that was the case, seems pretty ridiculous when everybody I have spoken to that's tried the 3blade on the gazelle says it makes them a much better aircraft.

Hi Keith,

 

Sad, but true. Recently removed a 2 blade Bolly from our Gazelle and refitted the original Allsize wooden one so as to remain 24 rego compliant.

 

Agree that something needs to be done to allow more efficient modern props to be fitted. Spoke to a number of CAR 35 engineers on the subject, but none seemed to know how to go about such things, and would have charged an arm and a leg in any case, so we gave up.

 

Cheers

 

Neil

 

 

[Guest Maj Millard]

Yes this is something I will try to highlight if elected to the board. Obviously we are running the so called "non-approved" props for a reason...not because they look sexy, but because they are better, more efficient, fuel saving and SAFER !!!!!.......we have been running them for sometime now, as have the rest of the known world, but CASA have simply put the matter in the "too hard" tray and banned them all !.........once again Australia goes severely backwards. And can someone give me one example where one of these more advanced props has actually caused an accident or fatality, in this country. (sting double fatality excluded as the damage was done before the aircraft came to Australia, done against Rotaxs operating instructions and misrepresented here when sold as 'new' ?!!.).......................Maj...

 

 

[Keith W]

Hi Neil, was there any difference between the 2 props, which do you prefer, let's keep our fingers crossed that maj Millard can convince casa on the benefits of the none standard props. Keith.

 

 

[Neil_S]

Hi Neil, was there any difference between the 2 props, which do you prefer, let's keep our fingers crossed that maj Millard can convince casa on the benefits of the none standard props. Keith.

Hi Keith,

 

I was actually quite pleasantly surprised - the wooden prop has performed OK since it was refitted. It has been a bit bumpy on the occasions I have flown since the refit, but my impression would be a slightly slower rate of climb, but in cruise it is about the same as the Bolly (pretty much the book figures). I guess a slightly different pitch/shape would be one factor.....

 

Rgds,

 

Neil

 

 

[Blueadventures]

Yes this is something I will try to highlight if elected to the board. Obviously we are running the so called "non-approved" props for a reason...not because they look sexy, but because they are better, more efficient, fuel saving and SAFER !!!!!.......we have been running them for sometime now, as have the rest of the known world, but CASA have simply put the matter in the "too hard" tray and banned them all !.........once again Australia goes severely backwards. And can someone give me one example where one of these more advanced props has actually caused an accident or fatality, in this country. (sting double fatality excluded as the damage was done before the aircraft came to Australia, done against Rotaxs operating instructions and misrepresented here when sold as 'new' ?!!.).......................Maj...

Hi Ross

Have you sourced a comment fromDaffad L. He may have some useful information.

 

Cheers

 

Mike

 

 

[68volksy]

Been trying for years to get an approval for the 3-blade prop. The issue is nothing to do with CASA - simply the manufacturer won't stump up the funds to get the prop approved. It's the same story with all things aviation - if you want it certified then you stump up the funds. We found an engineer who could do it but we were looking at thousands to get the report done. Bolly seems to be happy selling enough of the 3-blades to not concern themselves with getting them certified. Business case just doesn't stack up i'd say.

 

Maj - unless you have the engineer's report stating in black and white that the props are "better, more efficient, fuel saving and SAFER" then you're wasting your breath methinks...

 

 

[facthunter]

Safer would be the issue. I have seen a few people replace props on gazelles and in two cases they put the original back on saying there was no perceptible improvement. Wood is NOT the most efficient as you can't go as fast TIP SPEED before it gets draggy due to compressibility due blade thickness. This affects big dia props on ungeared engines so is not likely to be much of a problem with the Gazelle set up. Composite should be more accurate as far as shape goes, and thinner section.. IF your new prop doesn't let the engine get full revs you don't get the power either, so pretty accurate matching is needed to get good results. Two blades should be more efficient than 3 (Marginally) but are usually used for ground clearance or tip speed reduction where dia being smaller helps. Nev

 

 

[Dafydd Llewellyn]

Hi RossHave you sourced a comment fromDaffad L. He may have some useful information.

Cheers

 

Mike

The reason why nobody will give a formal approval of anything other than a fixed-pitch wood prop., is that the wood prop is certificated in the course of the certification of the Skyfox or Gazelle. See if you can get a copy of a Type Certificate for any of the composite props (LOL). Without one, there's no way anybody will approve the use of one. I understand there's one model of Warp Drive prop that is accepted by the British PFA for use on an 80 HP 912 in a Trike; that's not likely to cut much ice with CASA. And yes, there has been a fatal of one of the Skyfox variants due to a non-approved propeller being fitted; I don't know whether it was a composite type - may have been a ground-adjustable wood type. Maybe things are changing, but there were no certificated composite props around when the Gazelle or its predecessors were undergoing certification.

A FP wood prop can be certificated under FAR Part 35 by a documented flight history of 50 hours, a specified portion of which is at maximum RPM, maximum power, in cruise or climb. That can generally be achieved in the course of the Type Certification testing. I'd suggest Maj takes a look at what is required by FAR Part 35 for a composite-bladed prop. before he tackles CASA; if he does, he'll see why there are so few certificated composite-bladed propellers around.

 

Fitting a non-standard FP wood prop also requires formal approval; and it involves flight testing to verify that the engine does not overspeed in climb at full power, or at Vne with the throttle shut. Also, the takeoff and climb performance needs to be checked, to ensure the performance data in the flight manual are still valid - or if not, to update the data. It means, in effect, a re-run of those parts of the original type certification flight tests. This is not a cheap process.