[JAG]

Tom,

Regarding your question around temperatures and the subject of wind loading. Temperature certainly has an effect on a rotating component that is greased, and in addition, the wind loading from airspeed does provide an amount of resistance to the hydraulic system. It could be that with just a little cold grease and some airspeed provides enough resistance on the hydraulic system to make that pump work that much harder and draw more current. These are not your root cause however, just possible contributing factors in my opinion.

I used to be a crew chief on a L382 Hercules (commercial version of the C-130) and we operated in the Canadian Arctic. Ground temperatures were often below 40 C. We kept everything greased and clean on the gear and never had problems. One winter we were working out of Amsterdam - was a nice break from the cold. Of course in Holland, it seemed like it rained every day, and instead of a parka, I wore a rain suit to maintain the aircraft. We had to come back to Canada at Christmas to do a few fuel-hauls. This was the first time I discovered how grease can hold water in suspension, and when it gets cold, it can loose its flexible properties. We had to stop in Iqaluit (Frobisher Bay for the old-timers) for gas, and when the crew went to put the gear down, it was frozen! The hydraulic system could not overcome the drag of the moisture laden grease in the gear screw jacks. I took meticulous care of this landing gear - never had a problem until this day. Anyway - we ended up getting the gear down...I had to hand crank the mains down on both sides. That is a whole other story.... The problem was solved once I was able to purge all the old grease out of the ball nuts.

So the point of my rant is this - landing gear (in my experience) needs constant TLC. Cleanliness in areas that need to be clean, and consistent fresh lubrication where it is required. Old Grease and lots of grease is not good. Actuators need to be clean, and pivot points free from dirt and build up.

Cheers!
Jeff