TSRABECOMING

I am looking for information of the reasons that Engine manufacturers paint their engine spinners with black and white strip.

I heard that one reason is forr bird strike prevention. Are there any support document or link about this reason??
Thanks
TS

skwinty

The purpose of this pattern is to provide ground personnel with a visual cue that the engine is actually turning. This simple warning is an important safety feature that can often prevent tragic accidents when personnel are working near rotating engines. This precaution dates back to at least the 1930s when spirals appeared on the spinners of many propeller-driven aircraft. Otherwise, a propeller rotating at high revolutions per minute can become nearly invisible and very difficult to see to an observer on the ground. For example, think of the spinning blades of an electric fan or ceiling fan. As the speed of rotation increases, the blades become increasingly difficult to see.

dazdaz1

Skwinty......Although I have no experience in the aviation field, I would (with props) imagine the high sounding revs of a engine might indicate the props are spinning at a good rate of rpm. Having said that, (in your defence) the ground crew may be wearing ear defenders.

Daz

Matari

Dazdaz,

The rotors windmill without power, so it is helpful to see they are in fact spinning.

Trivia, which is the "Dolly" and which is the "Madonna" spinner, and why?

skwinty

Even with these visual and audible cues, people still manage to walk into spinning propellers.

skwinty

Madonna has the pointy tits.

dazdaz1

I would suggest 'Dolly' has the bigger ones, did you see the web photo? I'm off before I get banned again.

Daz

Matari

Skwinty didn't need to squint to guess that one!

I once heard the official reason for the different shapes was that Dolly shed ice better than Madonna, and I can only imagine that is true!

stevef

The apron can be a pretty loud place sometimes. I've worked at a cargo hub where there were often two or three turboprops with engines running at the same time so noise isn't necessarily an indication of which aircraft is 'live'.
Discontinuous black & white (flickering) concentric markings on the propeller blades seem to be the most effective warning of rotation.
Aircraft are like guns in some ways - perfectly safe until you forget that they're dangerous...

FCeng84

While an operating engine produces quite a loud noise signature, on a busy flight line it is easy to confuse which aircraft/engines are generating the engine noise that is being heard. Ear protection further impacts the ability to determine a noise source.

One thing I have found curious (my nerdliness is showing here) is to notice that turbofans on parked jets often windmill in the wrong direction. Planes at passenger gates (head in toward a several story building) often see a localized tail wind that causes the fans to turn backwards.

Leatherman

The straight white line on the spinner is the norm I think. Mostly for ground staff warning.The large spiral is owned by someone and it costs the user. I think it was proven to be bird scaring at some distance.

skwinty

Didn't help Scully.

That story is for the birds, methinks.

tonytales

You would be surprised how numb you can get when working around running engines. I was in the hydraulic hell hole on a DC-4 adjusting autopilot hydraulic pressure which required the engine be run. After a half hour in there, no ear protection in those days, amidst a lot of whining and screeching noises from the hydraulics and the engine noise, I backed out the hatch which was just fwd of the wing L/E on the right side. Engine of course was right there, even at idle making a great deal of noise. I turned right, took a step and realized there was a prop whiling a foot in front of me. Another step and I would have been into it. Stupid of me of course, a lesson I learned at no cost fortunately but my knees still get that weak tingle whenever I think about it.

Capt Claret

Spend enough time around them and they tend to blur into the background, which is why vigilance is required at all times, but it's hard to completely prevent the human condition of complacency.

Turbine D

Fan spinner cones shapes - An interesting subject...

Not only does the shape have an impact on shedding ice, the shape plays an important role in water ingestion. There was an early B-737-300 incident with CFM56-3 engines where this was learned. TACA Flt. 110 was beginning decent into New Orleans and passed through some heave rain. Both engines flamed-out and the aircraft landed without power on a levee near the NASA facility. This aircraft had "Madonna" spinner cones on the engines. These spinner cones evolved from the original CFM56-2 which had long, large & pointy cones.

What was determined was the FAA test for water ingestion, during the CFM56-3 engine certification process, did not call for enough water and did not duplicate what was encountered in this rain incident. So, the spinner cone was changed from the "Madonna", to the "Dolly". It isn't that pointy cones don't work, they do but it depends on other factors as to how well they work.

Personally, I like the "Dolly" size and shape the best!

The stripes painted on the cones are primarily for ground crews, the bird theory is still a theory. The paint stripes can also tell which way the engine fan is turning. The fan can be windmilling in the opposite direction of normal rotation depending on wind direction. I am not sure, but, this could have a negative effect on starter life?

barit1

Turbine D:Negatory - The starter cranks the core rotor, which is (almost) never windmilling from terrestrial wind. And at very low rotor speed, there's negligible aero coupling between the core and fan. Most modern engines have minimal restrictions against starting in a tailwind.

(Although - recalling the first PAA 747 revenue flight, Jan. 1970, an engine stalled/overtemped when started in a tailwind. We've learned a lot since.)

Turbine D

Thanks barit1,

You cleared up the uncertainty I had in my mind about that.

lomapaseo

Not true

Nobody owns the spiral and even the shape is debateable. The shape does affect where the ice and bird guts go behind the fan, but in the end it's a trade with other parameters like RPM, aircraft speed and exactly what point the bird-ice-hail-rain drop hits

The birds proved that any of the paint schemes don't bother them a bit (FAA ingested Bird data)

tonytales

The Bristol Britannia with its Proteus engines had a prop brake to prevent windmilling on the ground. When starting engines in a tailwind,you would go and hold the prop to prevent backwards rotation after brake release. The Proteus was sensitive to wind up the kilt and could be hard to start. The electric starter turned the engine compressor and would wind up but the free turbine driven prop could be held. At light-off which was audible as a thud, you would feel the prop pull out of your hand and you could amble away to the next engine to be started. You could see the pax noses pressed against the windows looking down at you as they wondered what was going on.
I agree the spiral paint on the spinner is for ground crews. It is harder than you think to determine which engine is running on a busy ramp.

Eman Resu

The bigger question is why did the Germans do it and who's copying who?