PIPER AIRCRAFT

[Captainkirk]

PA31-310 Navajo

The pilot complaint was that the gear handle would not return to center using the left engine. Preflight check requires you to check pump output by selecting the gear down position with one engine running. With the pump operating properly, the selector handle should pop back to neutral within a few seconds. This was the case with the right engine, but not the left. Both Piper's maintenance troubleshooting chart and tech support targeted the left pump as being defective....except, that it was freshly overhauled!
The resolution to the problem was that the RIGHT engine check valve was bad (located at the front of the powerpack unit) and allowing left pump pressure to bleed back through the non-operational right pump (right engine off) The tip-off to this problem was that all the other check valves were internal to the power pack and would've affected BOTH hydraulic systems. The left engine check valve is readily visible from the right forward fuselage panel, however, the right one is not visible and requires access through the forward baggage compartment (not such an easy job!) Hope this helps someone!

[Spinner]

good point Gary. I have had this problem appear and disappear on the chieftan wich has basically the same configuration. I know a good place to start my troubleshooting next time.

Paul

[Spinner]

Here is a new one. Did hydraulic pump test on the runup and handle would not return to neutral. Boys brought it in the hangar for troubleshooting.

With the hydraulic cart gear would go all the way up and D doors would close about halfway. They then sat there and shuddered for a while until there was a loud bang from the powerpak and the doors operated normally.

Same thing happened on the way down. Gear would come down normal but doors would not close. Stay tuned troubleshooting in progress.

PA31-350

[Captainkirk]

Originally Posted by Spinner

good point Gary. I have had this problem appear and disappear on the chieftan wich has basically the same configuration. I know a good place to start my troubleshooting next time.

Paul

Gary?
This is the Captain speaking!

[Spinner]

hmm must be the good drugs that I have been taking (hydraulic fluid and avgas). Now do I feel really bad.