AMMETER READING ON PIPER LANCE

JLINNX01

GROUND CHECK IS NORMAL, GET A GOOD CHECK BY TURNING ON PITOT HEAT, LANDING LIGHT IS LED SO IT NO LONGER GIVES MUCH OF A JUMP.DURING RUNUP AT 2 2000 RPM STILL NORMAL. WHEN RETRACTING GEAR ON TAKEOFF AMMETER SHOWS BIG JUMP, ONCE GEAR IS STORED, PRESSURE SWITCH SHOULD SHUT OFF PUMP. NOW IS WHEN I NOTICE PULSING ON AMMETER, PULSING GOES AWAY WHEN GEAR IS EXTENDED. ANY IDEA WHAT IS GOING ON HERE?

R-Trans

I am not a mechanic, but I do own a Lance. I believe the hydraulic system tries to maintain a certain amount of pressure on the system when the gear is stowed (so it will stay up and not slip down). The pulse to me would indicate that the system is losing pressure and the hyd pack is activating to build the pressure back up and keep the gear stowed. This would indicate a leak in the system. Usually this would be one of the wheels retraction cylinders. Do you have any drips of oil under one of the gear? Or on the gear door? If not a cylinder, then it must be the pack itself or internal plumbing. You should see oil somewhere.

If left unattended, the pulse will eventually become more continuous. Eventually wearing out the motor in the hydraulic pack (from extended use) or from loss of oil. My Lance has had two hydraulic packs in its days.
The first one was from the electric motor just being toasted. Brushes melted to the armature and it was a mess (just wore out). In your case brush wear or metal to metal would definitely explain high amp reading. If you (or your mechanic) have never looked in the brush cavity of the hyd power pack motor, I encourage you to do so very soon.

Then I sold the airplane and bought it back 10 years later. Looking in the logs I see the previous owner had changed a power pack too. Upon investigation, I discovered it was from a leaking cylinder that had caused the pump to run almost non stop.

I am guessing you will be in the same boat over time unless you find your leak.
Hope this helps.
Jeff

R-Trans

You could verify what I have said by pulling the landing gear breaker in flight and see if your pulse goes away.
DON'T FORGET TO RESET THE BREAKER BEFORE LANDING

pricewr

I had the same problem in a toga. 2 power packs later and finally a nose wheel actuator. problem solved, 6 years now

Scott Sherer

Hi,
I've had a Seminole and three Seneca's, all with a power pack. When the gear system has a leak and the hydraulic pressure decreases beyond a certain point the pump cycles, just as you surmise. Your A&P can fix this... good luck and let us know how you make out.

Scott Sherer
N344TB
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