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Gear motor blowing CB
- Gordon C Keymer
- Posts: 2
- Joined: Fri Sep 27, 2013 2:23 pm
Re: Gear motor blowing CB
JIMICS2452- ICS member
- Posts: 254
- Joined: Sat Mar 09, 2002 9:26 pm
- Location: Pine Shadows Airpark - North Fort Myers, FL
Re: Gear motor blowing CB
Patricia Jayne (Pat) Keefer ICS 08899
PA-39 #10 Texas
N3322G- ICS member
- Posts: 1911
- Joined: Thu May 08, 2008 1:58 pm
- Location: Fort Worth, Texas area
Re: Gear motor blowing CB
Definitely take Matt Kurke's guidance, check the wiring - perhaps put the plane on jacks retract and see what happens, if it stops short - ohm out the wires. Beyond that look for something mechanical and check the retraction loads.
- Charles
Charles Schefer- Posts: 563
- Joined: Mon Mar 12, 2012 7:09 pm
Re: Gear motor blowing CB
Check your generator, regulator, and battery.
The shunt wound motor in the gear transmission will pull enough amps as required to keep moving as the field coil voltage drops or as the rotor stalls. If you have a low battery, weak regulator, dirty brushes then the voltage drops, the gear motor pulls a massive amount of amps, enough to trip the breaker.
Your regulator should keep the bus voltage around 14.7 volts when charging the battery.
My original equipment regulator was completely shot. Replaced with new electronic one and my gear issues (and another of other electrical issues) went away.
Once I correlated it to the electrical system I could even repeatedly make it occur, for example, by turning on all the electrical loads such as the nav lights and pitot heat, which draw huge current, load the system, and drop the voltage. With all that on the gear would pop the breaker on the way up. With it off it would work - most times.
During the gear swing on jacks, there is less load on the gear and on the electrical system and the battery can do the job as the generator and regulator isn't involved. So the breaker doesn't pop during the gear swing.
Measure the bus voltage while the generator is allegedly charging the battery and see if the voltage is below specification.
There is nothing more frustrating than fixing something that isn't broken. I'd make sure your electrical system (battery, generator, regulator, wiring) is up to snuff before getting into the really expensive stuff...
William Hughes- Posts: 97
- Joined: Mon Apr 21, 2014 9:23 pm
- Location: Saskatoon, SK