Prepping Your Pitot Tube

As you approach your aircraft, you notice that you forgot to cover the pitot tube the last time you flew. Oh well, it happens all the time. No biggie, right?

It is according to NTSB Report CEN17LA184.

While in flight, the pilot of a Mooney M20E noted a discrepancy between what was displayed on the airspeed indicator and what he expected to see.

Attempting to land, the pilot stated that the airplane would not “settle,” and initiated a go-around. On second attempt, the airplane floated again, consistent with a higher-than-indicated airspeed. He “forced” the airplane onto the runway. The airplane collided with numerous objects, resulting in substantial damage. No injuries.

Probable cause: Inaccurate airspeed indications due to contamination of the pitot-static system with insect remains.

Warmer Spring temperatures mean bugs are back. Every region has native insects and spiders to deal with, but two common offenders seem to live everywhere: silverfish and wasps. No one’s pitot tube is safe from these and other bugs looking to homestead in your aircraft.  

Even if you cover your pitot and hangar your aircraft, you should inspect your pitot tube carefully before every flight. Here are some tips to minimize pitot pest problems.

DO:

• Use a bright flashlight for inspection, day or night. It’ll help you peer farther into the tiny opening of the tube. If you already keep a headlamp in your flight bag, that'll get the job done.
• Check the drain hole on the backside of the pitot tube.
• Check the static port, which can also become clogged, so don’t gloss over that checklist item.
• Tell your A&P if you find or suspect a blockage. Let them handle it with the correct testing and repair tools.

DON'T:

• Blow into the pitot tube because anything that’s stuck in there is now deeper inside your pitot/static system.
• Stick anything into the pitot tube (for the same reason as above).
• Fly with a fully or partially clogged pitot or static port. Not only is it dangerous, but it also could be illegal (since it makes several instruments listed in 91.205 technically inop).
• Try to fix it yourself unless you are an A&P.

Quiz