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Topic-icon Landing gear problems

  • James Weller
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2 weeks 4 days ago #1791

My PA28R will retract, but on commanded down with the gear lever, it simply drops and locks without hydraulic motor running at all. Up until this last flight, the motor did operate. What could be going on here? The emergency extent lever appears to be loose- not connected to anything. Thanks, James

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2 weeks 3 days ago #1793

It sounds like the emergency down valve is stuck open or is being held open. Do you know if the back up extender system have been de activated?? Piper Service bulletin 866A is the bulletin that details the de activation procedure. If it has been deactivated, the spring that keeps the emergency down valve (also called the free fall valve) should have been relocated.
I suspect you'll find that the spring that keeps the valve closed has broken or become disconnected with the emergency down handle, or the valve has is stuck open due to crud inside the valve.

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  • James Weller
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2 weeks 3 days ago #1797

Steve, I requested that the back up extender system be confirmed operable in my last annual. On a test flight, the report was positive for that- it does work as designed. So it seems as though your observation is correct and I can direct my mechanic to look for a broken or disconnected spring. Why would the gear stay up anyway if this valve was open during and after the retract sequence?

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2 weeks 3 days ago #1799

the electric motor in the landing gear hyd system rotates one way for gear up and the opposite way when gear down is selected. When the handle is in the up position there is pressure on the up side of the actuating cylinders. If the pressure in the gear up manifold drops to 1000 psi, a pressure switch closes and power is applied to the motor to pump up the pressure. When the pressure reaches 1500 psi the pressure switch opens and the motor shuts off.
When the gear handle is moved to down, the motor reverses rotation and applies pressure to the down manifold. As I understand it, the second down pressure no long bares against a shuttle valve in the hydraulic reservoir/control a path is opened for the fluid in the up lines to return to the reservoir.
Again, as I understand it, until gear down is selected hydraulic pressure keeps the gear up in the wells.

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2 weeks 3 days ago #1800

Steve, I know just what to say to my mechanic tomorrow. I am going to remove the rear seats today in hopes of reducing his labor time since this valve is located beneath. Thanks, I will let you know the results.

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2 weeks 2 days ago #1801

Excellent, glad I could help.
Your follow up report is welcomed.

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