Ever wonder why parked planes have red labels with capital letters that say “REMOVE BEFORE FLIGHT”?
The end of the red flag often has a hatch or a locking pin because many parts in an airplane are vulnerable and need to be properly covered or secured before a long parking time. Pitot tubes, APUs (Auxiliary Power Unit), engines and more. There are many parts to be covered and secured during long term parking.
For example, the pitot tube that measures air velocity has a small, tiny entry hole in front of it, providing the perfect habitat for flies or other small insects.
Or if your plane is parked on a runway in the desert, sand can build up in the pitot tube over time, causing an inaccurate or no reading.
A similar situation is experienced during the winter months. Melting snow can enter the pitot tube and freeze and block it.
Birgen Air Disaster and Remove Before Flight
On February 6, 1996, the plane belonging to Birgen Air, which took off from Gregorio Airport in Puerto Plata, Dominican Republic, with 180 passengers and 9 crew, crashed into the Atlantic Ocean.
The reality that emerged in the accident analysis was interesting: The plane with the passengers coming for a Caribbean vacation waited in Dominican for 25 days, the pitot tubes that had to be covered were not closed. During this parking time, wasps had nested in the tubes and prevented the airflow of the tube during flight. As a result, pressure increased and pitot tube gave a wrong signal showing the speed of the plane higher than it was.
Same comes with locking pins. Locking pins or bolts are very often used to prevent rudders, ailerons and stabilizers from flapping about in the wind and damaging the hinges and joints over time. Therefore many light category planes have a little hole in the yoke to fit a bolt in place at a neutral position of the rudders to block the moving when exposed to windy conditions.
Big airliners, which sometimes are being parked outside for an entire winter or summer, the complete engines are being cover up to prevent the turbines from windmilling and getting damaged due to friction without lubrication of the inner parts of the turbine.
Even the doors and all other vents and holes are being completely sealed up to reduce stand damage.
Therefore aircraft manufactureres have come up with an easy and reliable solution, cover up what is valuable and attach a huge “REMOVE BEFORE FLIGHT” sign onto the cover or locking pin to make it stand out for the pilot whilst performing his outside check!
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