PilotPete
Well-Known Member
- Joined
- Mar 16, 2011
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I have the HYC5005 Prestolite hydraulic pump on my PA32R-300, and I've noticed over the past while that there has been some hydraulic fluid drips on the underbelly of the aircraft, right at the back of the nosewheel well - not alot, but just enough to be bothersome. I figured there was a slow leak either in the pump or the lines coming from the pump, but my mechanic couldn't find anything at annual.
The other day I went to drop the gear, and no go. No "in transit light", nothing. I had to manually drop the gear.
When I looked at the pump I noticed two things. One, the floor under the pump was wet with hyraulic fluid, as was the underbelly of the plane; and two, the vent screw on the reservoir was tightened right down. The manual for the pump says to ensure the vent screw is backed off two complete turns or you can "do damage to the pump". OK, a third observation was that the hydrualic fluid was way down in the reservoir when I removed the fill screw. Doh!
So questions:
i) Does the pump stop working if the fluid level drops below a certain level (ie. is there some kind of level sensor or float that shuts down the motor if it detects low fluid) ? As I said, I didn't even get the "in transit" light coming on.
ii) What damage could occur if the vent screw was tightened down? I'm guessing there could either be a high pressure build-up or a vacuum set up (hence the need for the vent!), but I don't understand how either could occur if the system is closed (ie. fluid in = fluid out). Presumably, pressure somehow became elevated in the reservoir and that forced some fluid past the O-ring seals.
My plan is to clean the area really well, refill the reservoir, set the vent screw properly, and then run the gear on jackstands and see what happens. Do you think the seals will need to be replaced? Any other potential damage to the pump or motor?
The other option I'm toying with is to get an overhauled unit and send mine in for service.
The other day I went to drop the gear, and no go. No "in transit light", nothing. I had to manually drop the gear.
When I looked at the pump I noticed two things. One, the floor under the pump was wet with hyraulic fluid, as was the underbelly of the plane; and two, the vent screw on the reservoir was tightened right down. The manual for the pump says to ensure the vent screw is backed off two complete turns or you can "do damage to the pump". OK, a third observation was that the hydrualic fluid was way down in the reservoir when I removed the fill screw. Doh!
So questions:
i) Does the pump stop working if the fluid level drops below a certain level (ie. is there some kind of level sensor or float that shuts down the motor if it detects low fluid) ? As I said, I didn't even get the "in transit" light coming on.
ii) What damage could occur if the vent screw was tightened down? I'm guessing there could either be a high pressure build-up or a vacuum set up (hence the need for the vent!), but I don't understand how either could occur if the system is closed (ie. fluid in = fluid out). Presumably, pressure somehow became elevated in the reservoir and that forced some fluid past the O-ring seals.
My plan is to clean the area really well, refill the reservoir, set the vent screw properly, and then run the gear on jackstands and see what happens. Do you think the seals will need to be replaced? Any other potential damage to the pump or motor?
The other option I'm toying with is to get an overhauled unit and send mine in for service.
