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AVIATION SAFETY

Dave Fry, WVFC CFI and Aviation Safety Counselor dgfry@aol.com

The Potato Rhythm

Before reading this article, please check out the YouTube video - http://www.youtube.com/watch?v=3w_v0k57KhE&noredirect=1, or Google Beaver Ballad.

Every time you fly something new, you add to your own flying database, and learn things that apply to other aircraft, and things that you’ve learned in other aircraft help you learn the new one – and provide (in some cases) negative knowledge transfer.  As you may have guessed, the previous statement can be used to justify spending the money to fly something that has no practical purpose for the pilot (me, in this case).  I can talk myself into almost anything, or as my wife says, “It’s not willpower you lack, it’s won’t power.”  Oscar Wilde (I believe) captured it with, “I can resist anything but temptation.”  I digress, again.

This week I flew a Pilatus with a couple of owners up to Seattle, home of Kenmore Air, the world’s largest seaplane operation, so the question of what to do while my clients were off taking care of business kind of answered itself.

As soon as I knew I had a flight to Seattle, I arranged to fly a Beaver on floats with a Kenmore instructor, and already having a Single Engine Sea rating, I knew something about floatplanes.  In fact, I finished my Commercial Single Engine Sea rating at Kenmore back in the days when one could rent a seaplane after getting the rating.  I flew there a few times after the rating, but even though I’ve flown a variety of seaplanes, I’d never flown the Beaver – the quintessential floatplane.

There are any number of differences between land planes and seaplanes in general without even considering the differences that make the Beaver unique.  A couple of the obvious things that come to mind include:

- A preflight that involves pumping out the floats

- A preflight that often means turning the plane around while making sure it doesn’t blow into another

      plane

- Performing the run up and moving at the same time (no brakes in the water)

- A takeoff that starts with holding the wheel all the way back, then at the right time pushing forward to pitch the plane down to the takeoff attitude

- Landings that (most of the time) can be directly into the wind, since there aren’t runways in the water (mostly)

- Using the direction ducks takeoff to indicate wind direction instead of non-existent windsocks.  However stupid you think ducks are, they are smart enough to know not to takeoff downwind.

- Landing without being able to tell your height above the landing surface – when the water is glassy, especially when there are high clouds, you look down and don’t see the surface, you see the sky, and in extreme cases, you can’t tell within the nearest 100 feet how high above the water you are.

- Taxiing power-off into the dock, and jumping out while the plane is still moving (the only time I jump out of a moving airplane) to bring it to a stop alongside the dock.

The list is actually a lot longer, but you should get the idea.  And each model of seaplane has its own idiosyncrasies.

My instructor, Jeremy Schultz started by briefing me on the differences between the Beaver and the previous seaplanes I’d flown, and we discussed power settings and procedures.  Pretty much the same thing you’d expect during a checkout in any new airplane.

The first really different thing I noticed during our flight was that the flight controls were extremely light, even with no airflow across the control surfaces.  Jeremy told me that the control feel would remain very light – fingertip light – throughout the flight.  In addition, the oil fill tube and dipstick is actually in the cockpit, and the acceptable oil range is 4.5 to 6 – GALLONS!  We started the engine, and that isn’t done the normal way, either.  Prime, as usual (though the primer is on the doorsill to the pilot’s left), master on, pump the throttle a couple of times and then BARELY crack it open, propeller to high RPM, and mixture rich.  Sounds pretty normal up to this point, then you lift the starter switch and after four or five blades go by, switch the mags to both – which is a little different, but pretty normal for a radial engine.  Then things start getting weird.  It takes a LONG time to warm up 6 gallons of oil, so the standard procedure (the plane is tied down, remember) is to leave the plane idling for about 10 minutes and come back to find the oil temp at 100 or higher.  Don’t do this with a West Valley plane!!

Setting the power for the run up isn’t completely scientific, but it’s way cool.  At low power settings, (mixture brutally leaned, and carb heat on) the engine doesn’t idle smoothly, but makes a rhythmic sound that Jeremy described as, “potato”.  Or perhaps “potatoe” if you’re Dan Quayle, oops, another digression.  At any rate, when idle is set correctly, the engine will call out “potato” about once per second.  And of course, it changes a bit as the engine warms up, but the sound was so cool, that I stayed with the plane while it warmed up – radials sound great!  For ten minutes, I listened to the “potato rhythm”.  Love it!

Finally warmed up, we turned the engine off, untied the plane, shoved off, and fired up the plane to taxi away from the dock.  With the water rudders down (it takes two hands to lower them), the plane taxies about the same as a 206, but the conditions were calm, so things might have been a bit different had there been more wind – this thing has a lot of surface area to get pushed around.  The mag check with wheel all the way aft results in a nose up attitude and needs a bit of right rudder to keep from drifting off to the left.

We did a 360 turn at low power to clear the area for takeoff, and then brought the power in for a step taxi to kind of explore the feel on the step – important for both takeoff and landing.  The controls were still amazingly light, even the push to bring the nose down for the step taxi.  The Beaver has a HUGE sweet spot – the pitch attitude at which the plane accelerates best to takeoff speed.  Some planes have very tight sweet spots, but not the Beaver.

The weather was nice by Seattle standards, which means it wasn’t raining, but the skies were overcast at about 300 ft – plenty of altitude for a floatplane.  I mean, we weren’t going to do stalls, but we could takeoff, climb to “altitude”, turn, and land back on the water – what more could I want?  Most landings were glassy water landings, which means you establish the landing attitude and set up a 100 foot per minute descent, then when you see spray out to the side, you know you’re on the water, and you reduce power if you want to come to a stop, or add power if you want to stay up and step taxi.

I had a complete and total blast, and will try to do it again the next time I find myself in Seattle.

Maybe someday we’ll get a seaplane in our club.



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