The safest way to protect your pitot tube
The Pitot tube is used to drive the airflow to the airspeed indicator. If something blocks this small air intake the airspeed indicator stops working. When aircraft are parked their Pitot tubes must be protected to make sure that they stay clean. Dust, dirt, grass, bugs… many things can block a Pitot and possibly damage it.
The easiest way to protect a Pitot tube is to use a so-called Pitot cover. This can take the form of a fabric, leather or plastic cover shaped to fit the Pitot tube. They are usually fitted with a long “REMOVE BEFORE FLIGHT” tag. Some are custom made, and some are even home-made. I’ve seen this one recently and loved it. Particularly because it is not protecting the Pitot tube of an experimental aircraft but of a Learjet 45.
The hazard associated with the use of a Pitot tube cover is simple: forget to remove it before flight. Flying with a non-working airspeed indicator is not something a pilot wants and there are two mitigation measures to avoid it: a good pre-flight inspection and the “speed is alive” call-out during the take-off roll. If the Pitot cover remains on, the airspeed will not rise and the take-off should be aborted.
I recently discovered an other way to protect a Pitot tube without using a cover. It is made of a small metallic cache that obstructs the tube’s opening. It is mounted on a pivot and when there is sufficient airspeed the cache pivots upwards. The airflow itself opens the tube.
The assembly is designed in such a way that if it fails the closing part can’t stay on but will detach and leave the tube clear. This is a very simple and clever device and I like it. If you have experience with it, I’d like to learn more from you. I’m particularly interested to know how this behave in icing. Is it safe to be mounted on a heating tube, and is there not a risk that the ice closes it down?
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