Gear goes down half way... then stops

[KS Arrow Pilot]

For anyone who is familiar with the piper arrow... I'm flying my 1968 arrow yesterday solo, breaking in my rebuilt engine. After a 2 hour flight, I return to my airport and hit the gear down switch. I can hear the gear start to drop... then stop and no green lights. No light on the "gear in transit" light. I can feel the flight characteristics that something isn't right.

I radio unicom ( it's an uncontrolled airport ) and make a low pass while they look at me fly by. They confirm my gear is down "half way" and not locked. I try to put the gear back up, but nothing happens. I hit the "emergency gear down" button which is supposed to disconnect the gear from the hydraulics and let it free fall. Nothing happens. I push full right then left rudder hoping the wind will lock the gear. Nothing happens. I cycle the gear switch a couple more times, and nothing.

The fuses are fine. I check the panel lights and they are fine. Then on my forth pass, the gear mysteriously comes down while I'm climbing back into the pattern. I get all 3 greens and I can feel in the controls that the gear is now down.

I land and taxi back to the hangar. There is no sign of hydraulic leak. This am the mechanic puts the plan on jacks and cycles the gear 10 times and it works perfectly every time.

So... now we have to figure out why it didn't work yesterday. My feeling is that there is an electrical short between the switch and the motor. But I'm also ****ed that the emergency gear down switch didn't work right.

Anyone have any ideas on what we should be looking for?

 

[Skylane81E]

Hydraulic leak, if not leaking out then an internal leak.

First guess is the free fall valve, there is a tiny little oring in there that seems to be the weak point in the system.

I test them by jacking the plane and retracting the gear. If it won't go up all the way I cap off one of the lines going to the valve and try again. The gear should be able to stay up with the power on without cycling the pump more than once in a 5min period.

They didn't free fall because the springs need the inertia of the gear to fully lock them. And when starting from a half down position it's a crap shoot. I have had to g load the plane WHILE holding the free fall lever down to lock the gear before.

 

[bbchien]

ON THE JACKS short out the pressure limit switch, which is a consolidated Controls Type 211C243-12, and see if it works. Ask me how I know.....

 

[Skylane81E]

ON THE JACKS short out the pressure limit switch, which is a consolidated Controls Type 211C243-12, and see if it works. Ask me how I know.....

I've fixed this failure mode as well.

If the motor is shutting off before the cycle completes suspect this switch, if the motor continues to run but the gear fails to complete the cycle then check for leaks.

 

[flyer]

I had a arrow come into the shop years ago with the opposite problem, his gear would stop half way up.I checked everything and found it to be a broken wire on the gear leg inside the wiring harness going to the ground safety switch and when the gear would go up it would disconnect the switch. Wire replaced and all was good again.

 

[Sac Arrow]

That happened to me once - the gear slowly came down halfway in flight then stopped. I was unable to cycle the gear, but I was able to get the gear down via the hydraulic dump valve. Turned out to be a busted hydraulic line feeding one of the mains.

 

[Henning]

Look for loose parts and damage in your gear well, it was possibly physically bound.