Compans swing on float plane

[Bede]

Is there any way to do a compass swing on a float plane other than take it out of the water and tow it to a compass rose? How do you guys do compass swings on float planes?

[Heliian]

You'll need a fiberglass boat with wooden paddles and an oarsman. Anchor the back end of the plane and do your cardinal checks with a master compass. Have a radio with you and give the pilot instructions on tuning the compass or have another person in the cockpit.

Pro tip: shoot from behind the aircraft so as not to get run over if the anchor comes loose.

Or do it like most other people and use the gps track to tune it in flight or just pencil whip it.

[ourkid2000]

Even the thought of doing this in the water sounds hilarious.

[robertw]

Most small aircraft manufacturers do not spell out how to do a compass swing. You may see it in large transport category aircraft maintenance manuals. If there's a procedure in the maintenance manual, you need to do whatever it says. Otherwise AC43.13-1B Ch 12., Sec. 3, Para 12-37 lays out the acceptable practices for the compass swing. Unfortunately, that does not include the use of the aircraft GPS. I definitely wouldn't want to try doing this in the water as the engine is barking away at cruise RPM.

I have heard of people using the GPS to verify the accuracy of the wet compass, but that's not really the way to do it. If TC ever questioned you on how you did that compass swing and you used the GPS in the aircraft, there would be problems I suspect. See the attached pages from AC43.13-1B.

There's no "right" way to do it without pulling the A/C out of the water and getting to a compass rose.

[robertw]

...or just pencil whip it.

Really?!

[torquey401]

Most small aircraft manufacturers do not spell out how to do a compass swing. You may see it in large transport category aircraft maintenance manuals. If there's a procedure in the maintenance manual, you need to do whatever it says. Otherwise AC43.13-1B Ch 12., Sec. 3, Para 12-37 lays out the acceptable practices for the compass swing. Unfortunately, that does not include the use of the aircraft GPS. I definitely wouldn't want to try doing this in the water as the engine is barking away at cruise RPM.

I have heard of people using the GPS to verify the accuracy of the wet compass, but that's not really the way to do it. If TC ever questioned you on how you did that compass swing and you used the GPS in the aircraft, there would be problems I suspect. See the attached pages from AC43.13-1B.

There's no "right" way to do it without pulling the A/C out of the water and getting to a compass rose.

http://www.airpathcompass.com/

[ahramin]

NOTE: If aircraft is equipped, GPS can be used (allow for deviation) to establish reference headings for compass compensation. This technique will eliminate possible errors caused by gyro precession.

That is fascinating. I'm going to give them a call next week for more information. Very strange that they say to allow for deviation. I thought the whole point of the check was to minimize deviation and record whatever is left.

[Heliian]

Ok folks, calm down, I merely presented some scenarios.

To swing it you need a master compass.

Compass roses are essentially dead.

You don't have to be at cruise power, just running.

It's very easy to do.

[crazyaviator]

If the compass rose is accurate then use it , otherwise determine its deviation from the actual and do the math.
The swing is done with the engine taken up to cruise power to confirm that there is no excessive change in the compass. If there is no change between cruise rpm and low rpm (1000-1500) then use the low rpm. Be careful with overheating! Also, move the control column to cruise position and confirm no compass change or just leave it at cruise position, also ALL normal electrics on, Where are the headsets? Is the magnets housing all the way into the compass? Full of fluid? Did you take the magnetic screwdriver out of your pocket? After being diligent with all this, I wonder how many times the compass accuracy has gotten a pilot out of danger?

[BGH]

If you actually use the compass rose to do the swing make sure the beaching gear isn't under the plane.

Daryl

[crazyaviator]

Yes, once the guys line you up to North with the beaching gear on, and you bring the power up to check the compass stability, you may soon find the rose behind you in your peripheral vision, and the taxi way, and the runway, and the perimeter fence, and Airport road,,,,,,,,,,

[Zaibatsu]

Yes, once the guys line you up to North with the beaching gear on, and you bring the power up to check the compass stability, you may soon find the rose behind you in your peripheral vision, and the taxi way, and the runway, and the perimeter fence, and Airport road,,,,,,,,,,

Uhh.... okay.

[crazyaviator]

Some folks call that vehicle in the pic a dolly. Some beaching gear involve a wheel that is stuck into a round hole in the floats for "beaching" only ( no brakes) ,,,,, I was trying my luck at a joke !

[crazyaviator]

This is beaching gear ,,,likely has no brakes!!