Gear's Down - Prop's Fine

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Re: Gear's Down - Prop's Fine

Post by PilotDAR » Wed Nov 07, 2018 7:05 am

Although off topic a little, a few years back, I flew the formal noise testing for the 182 amphibian following a Continental 550/MTV prop, and Gomolzig exhaust for Transport Canada and EASA noise compliance. This testing involved 39 overflights of a microphone 2km from brake release. The passes were flown at different power settings. Considering RPM as a factor in power being developed, with full open throttle, and all other things equal, the difference in crossing altitude 2km from brake release between 2700 RPM all the way, and 2500 all the way (from brake release, takeoff, and climb to the microphone point) was 60 feet - hardly anything in the grand scheme of things. The flying was very precise, and recorded in many parameters, so the data (though gathered for noise) can be considered persuasive in terms of performance. The MT STC for this prop on this plane is limited to 2500 RPM (EASA, for noise), where the FAA STC for the same combination is 2700 RPM (noise compliance not required). The 200 extra RPM isn't really getting you much more.

So screaming the engine is not really getting you a lot more performance. On the other side of that, lugging it will create a detonation risk, a whole other discussion. Interestingly, when we landed at a very popular airport on an island in the north of Germany, were were asked to produce a noise certificate. Fortunately, the Transport Canada approved Flight Manual Supplement contained a statement about noise, and the airport officials accepted that. Without the noise certificate, our landing fee would have been many more Euros.
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Re: Gear's Down - Prop's Fine

Post by shimmydampner » Wed Nov 07, 2018 4:09 pm

C.W.E. wrote:
Tue Nov 06, 2018 7:45 pm
By the way what type of aircraft do you fly that requires full fine pitch on a normal missed approach?
The Viking manual for the 300 series twin otter calls for props full increase following selection of flaps 10 on approach, or when the reset props caution light illuminates, whichever occurs first. It specifies they must be full increase prior to 500' AGL when visual or 500' above DH/MDA on an instrument approach. For go around, the first order of business is to set takeoff power and ensure props are full increase. It also states that with flaps 10 and props full, aircraft performance and handling will be very similar to a normal takeoff.
The 705 turboprops I've flown also call for full fine props on approach and for go around.
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Re: Gear's Down - Prop's Fine

Post by C.W.E. » Wed Nov 07, 2018 4:21 pm

Interesting, it has been a long time since I flew a Twin Otter and I think it was a series 100.

So if that was what the manual called for that was the way I operated them.

As close as I can recall the last time I flew a Twin Otter was the winter of 1974/75 out of Johnston Point,

Here is a link to that flight

I must begetting old I guess. :mrgreen:
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