Some Piper Arrows were fitted with an auto gear extension system. This was an attempt by Piper to eliminate unintentional gear-up landings. The system operates as a function of airspeed and thrust and should the airspeed and thrust from the propeller, reach a point where the system thinks you’re coming into land, it’ll lower the gear. From memory, this should occur somewhen around 85 knots. (I don’t have the POH in front of me!)
There are occasions when you might want to over-ride this system. In an emergency, perhaps after an engine failure, you might want to control when/if the gear comes down. It would play havoc with your glide approach, if the gear came down too early. Also, the surface you’ve selected for your forced landing, may not be suitable for a gear-down landing – on water or a soft/boggy surface for example.
You might want to over-ride the system for take-off too, if you have obstacles or terrain on your departure path. As well as making the gear fall automatically below 85 knots, it will conversely not retract the gear until your speed/thrust is in the same range, regardless of the position of the gear selection lever. So if you’re adopting an obstacle clearance climb-out, you’ll be climbing at about 80 knots and so the gear may stay locked down, affecting your performance.
For these reasons, Piper installed an over-ride of the auto-gear extension so that the gear will only operate in manual mode. When this over-ride is activated, an orange blinking light flashes on the instrument panel to warn the pilot of the over-ride configuration.
As the years have passed, the rudimentary over-ride system has aged and on some Pipers, it’s difficult to adjust the auto-gear extension system so that it works as intended. On mine, for example, when we first acquired the aeroplane, it was not allowing me to retract the gear until my speed was in excess of 100 knots. We adjusted it, which has fixed that problem, but now it doesn’t lower the gear at 80 knots as intended.
So, since the system isn’t working as intended, I will often just over-ride the system, as it serves no purpose at the moment. Therefore you’ll often see the blinking orange light. I intend to have it adjusted one more time at the next major maintenance check, to see if we can get it working as intended. Alternatively, I may have the system completely removed – something many Piper owners have already done.