Monday, April 3, 2017

Remounting my replacement Dynon Heated Pitot tube

A very long time ago Dynon had some issues with their heated Pitot Tube probes where ice or water blockages were causing erroneous airspeed indications. Since Dynon's attitude reference is based on airspeed, this caused a number of different problems with their EFIS and autopilot systems. From some of the accounts that I read many of them were what I refer to as just short of loss of control types of events with the autopilot. This is not something I wanted to experience if flying IFR, or any other time for that matter.

They apparently found an issue with the location of their drain holes on the bottom of the tube, and after doing some robust testing came out with a redesigned pitot tube. I have not seen many flight reports since the new tubes were sent out to existing customers, but the ones that I have seen seem to indicate that the former problems have been resolved.

That said, I received my replacement Pitot tube a long time, and it has been sitting idle ever since. IN the past 2 weeks I have ben reviewing my blog posts and re-organizing my shop and getting re-acquainted with some parts that I had ordered for a variety of things. Among these are the bung kit for my future auxiliary fuel tanks, leading edge access hatch kit, LED landing, position, and nav lights from AeroLED, and the replacement heated pitot tube from Dynon.

If you search for the words Pitot Tube you will find a handful of previous posts where I performed the initial mounting of the tube to its mast. This did not go well for me the first time, and I plan to make sure it goes much better this time. The main reason for this is that the pitot mast that extends down from the bottom of the wing skin to provide clearance between the wing and the tube is a very expensive part that I do not wish to replace if possible. I messed up the mounting holes the first time and so I want to trim the pitot mast just a bit so I can redrill new holes.

I submitted a post to VAF to ask if there are any issues with trimming the mast below its original size. Airflow around the tube is a concern, as this is what is used to provide airspeed information in the cockpit. Click here to see the VAF post. If I can trim the mast down a bit I can redrill new holes and hopefully be done with that once and for all.

I've also got an order to aircraft spruce and Vans to make - time to start getting building supplies again. I am going to start with the pitot tube as a way to begin with a "small" project and then work my way back into the leading edge and fuel tank mess that I left almost 2 years ago. I need to make a decision about the fuel tank skin that messed up with a deep scratch made by a cleco while trying to force it into the skin and rib - not fun, and expensive if I need to replace the skin.

Like I have said before, I know exactly where I left off. it ain't pretty but I just need to tackle one problem at a time and move on. That is how you build an airplane one day.

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