February 29, 2012: Russia has approved ATR 72 and ATR 42 twin prop transports for use on non-tarmac runways. Nearly 40 percent of Russian airports and airbases use non-tarmac runways (dirt, hard sand, gravel). Larger commercial aircraft need government approval before they can use these non-tarmac runways. That's because the heavier aircraft have to be tested to make sure their landing gear can handle the softer surfaces and that the underside of the fuselage is covered with another layer of material to protect it from objects (rocks especially) that are thrown up by the wheels while taking off and landing. Maintenance crews for the heavy aircraft must also be checked to make sure they know of the additional cleaning and checks required to remove the additional dust and spot damage done by the debris thrown up by the moving wheels. The retractable landing gear of larger aircraft also has to be checked more carefully for dirt and damage and the tires wear out more quickly.
The ATR 72 is a 22 ton transport while its predecessor, the ATR 42, is a very similar looking 18 ton aircraft. About a thousand of these aircraft have been built in the last three decades and most are still in service. Western oil firms brought these aircraft in for operations in remote areas of northern Russia and Siberia and Russian firms followed suit. The ATR aircraft are popular with oil companies around the world and anyone operating in out-of-the-way places. The ATRs are built by a Franco-Italian consortium.
Many large military transports, and some large Russian commercial transports, are built and certified for use on non-tarmac runways. This process is expensive, as heavy transports require more elaborate landing gear. Russia did it for some twin-engine jets but only because so many airports in Siberia and the Far East had non-tarmac runways. This made these Russian transports exportable to many African and Asian nations that also had a lot of non-tarmac airfields. But the big seller was the An-24 series, which was built from the ground up for non-tarmac runways.