Several times in earlier sections of this web site, I mentioned the need to grease the bearings and other parts of the helicopter on a regular basis. Back in the old days, when one had the oil changed, one also had the car “greased.” Technology has replaced the need to grease ball and constant velocity joints, and to some extent, that is true with modern helicopters. But back in the old days, the H-2 and H-3 had many, many bearings and other rotating parts that had to be greased regularly.
The grease that was specified was a molybdenum disulfide compound that retained its lubricity when hot. We called the stuff “molly D” and it still is available today. Before I sold my tractor in the summer of 2013, I bought a commercial version in an auto parts store to grease bearings in the steering gear, drive shafts and other areas.
“Moly D” has one ugly characteristic that whoever specified the grease didn’t think of, or if he or she did, figured that if we greased according to the maintenance manual, the problem would never arise. We were told that when one used “molly D” in a salty environment, i.e. at sea, hovering at forty feet, or exposed to the salt air or if just rain,the molybdenum disulfide grease and as it deteriorated, it reacted with the chlorine in the salt air and water and turned into a mild form of sulfuric acid.
I’m no chemist, but sulfuric acid even in its mildest form is very corrosive when it comes into contact with aluminum and magnesium alloys. Guess which helicopters had aluminum skins and were full of castings made from those metals?
So, we were always giving the helicopters a fresh water bath to minimize the effects of corrosion. Or, we were flushing out the old grease and replacing it with new grease. And yes, molly D has its unique odor and a practiced nose could tell the difference between cold and hot molly D.