Harsh conditions are foiling Russian jets in Syria

Sand is a funny substance. We see it everywhere, we walk on it, and yet most people are pretty oblivious to what a disaster it is on machines with moving components. The sand itself is silicon dioxide, better known as quartz. If you look up a hardness table, you'll find that quartz is one of the hardest substances, definitely the hardest one we come into contact with every day (unless you have a diamond ding). This is bad news for engines which are typically made of metal, and nowhere near as hard. Dust and sand get into moving metal parts and chew them up badly. They get whipped around and cause nasty scoring and extremely fast wear on metal surfaces. In a gas turbine where you have a lot of precision, moving parts this is a nightmare.

Zaphod also brought up the glassification which is pretty funky. Obviously we can melt sand into glass, and in the right spots in a gas turbine you get some pretty high temperatures. You can get ingested material melting, and hardening in really bad spots in the engine. As it builds up and the engine vibrates you can get chunks of the glass falling off and getting further chewed up in the engine bits. If there's something worse than tiny pieces of glass, it's really big hunks of it. British Airways Flight 9 accidentally flew through a volcanic ash cloud during a night flight, and its engines got glassed. When it exited the cloud the engines were able to restart, but Air Crash Investigation did an excellent episode on what must have been the creepiest flight ever for the pilots and passengers.

Thing is Russia has had their time in the sand before in Afghanistan.You would think lessons learnt there would be applied to Syria..

There's an old pre-Cold War espionage story about a Russian who was allowed to tour an Allied aircraft mfg plant. He modified the soles of his shoes with deep cuts to pick up swarf and chips of the metals from the factory floor in order to obtain samples for Soviet examination.

Reciprocating internal combustion engines, like in a car, become quickly worn when there is a source of dirt being ingested by the air intake. Often, there's a leak around the air filter, or a gauze "performance" filter has been substituted, which allows big dirt particles to pass, unlike a paper filter. Another source is when guys try to clean the old filter with compressed air, usually in sandy areas.

When a used oil (lab) analysis is done, the dirt shows up as silicon in the spectral analysis. When the si spikes, you see wear metals from the engine also go thru the roof. Different metals correspond to different parts in the engine, notably upper cyl (bore) wear of al or fe, and the rings, in the form of excess tin and chrome dissolved in the old oil. Getting to the point, wear rate can be 20-30x faster than clean engines. So, in one oil change you can put 100k worth of wear on an engine, in extreme cases.

Just wanted to give an informative analogy on something interesting and put a number to the "sand" thing. It's quite real and if anyone wants to see some wild lab work from the spectral analysis of these used oil samples I refer to, I'll dig them out.

Used Oil Analysis is commonly used in heavy industry, military apps, aircraft maintenance, OTR trucking and other HD diesel engines like heavy equipment, locomotives or stationary engines like generators and to a smaller extent passenger auto engines. I use Caterpillar Labs for my UOAs, like $15 if you drop off your own....Blackstone is the most common.

Now many of us learned something new! (don't monkey w/your airfilters until they are due, like 30k miles minimum, paper filters don't clog, they filter BETTER over time)