[Mark Hislop]

Keven

I have had exactly the same problem, although my aircraft is a '73 P337. The gear would cycle down, but the doors would not close, and the gear motor would keep running. The gear would go back up, and the doors would close. Put the gear back down, and once again the doors stayed open, and the pump kept running. I pulled the LG circuit breaker and landed. Once on the ground, put the plane on jacks, and everything worked perfectly. Back in the air, the problem repeated itself...gear would come down and lock, but the doors would not close.

What caused the problem was the limit switch that indicates the gear is down and locked. Even though the gear operated properly, and was down and locked, the limit switch did not indicate so. The limit switch (actually three limit switches, one on each gear) must close, so that the valves can then direct hydraulic pressure to the door actuators and close the doors.

In my case, an adjusting shim had fallen out, and the limit switch on the right main gear was not making contact when there were air loads on the gear. Without the air load present, when the plane was on jacks, the limit switch made contact. Other problems with the switches could include intermittant contact at the terminals, dirt in the switches, or broken wires. There is a limit switch on each gear. I'll bet this is where your problem is.

By the way, shutting down the front engine when you have suspected gear problems is a procedure listed in the POH in my aircraft. I did the same thing.

Mark