All the Arrows I've flown have had the automatic gear extension feature. The system is driven by a pitot probe on the left side of the fuselage. On departure the system sees a higher airspeed than ambient due to the propeller slipstream. On approach this effect is reduced.
Note that the dump valve switch (on the floor between the seats and just aft of the flap handle) can be moved down to dump the gear or up and latched to override the auto down feature. This is used during slow flight/stall practice or when retracting early on departure.
I haven't had any issues with it.
- Kyrilian
"I have my airspeed sensing switch set a 90 knots, in the gear-up
circuit, so that no matter where the gear switch is, it can't raise the gear
unless the airspeed is greater than 90 knots.
Same on landing. I fi forget to put the gear switch to down, the
gear will come down anyway at 90 knots."
As I recall Piper used to have an automatic
gear extension system on the Arrow. After some accidents caused by the
gear coming down before the pilot expected or wanted it to, and sometimes
failing to retract because best angle climb speed could be below
the gear extension speed, Piper published a service bulletin
recommending disabling the automatic gear extension system. Sounds to
me like the system was too simple, using one set airspeed below which the gear
would extend if it was up, or stay down after takeoff even though the gear
switch was in the retracted position. There was an override switch
but too often the pilot forgot about it, especially in a tense
situation.
Tom Gourley
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