Can a turbulence cause an airplane to crash?

Severe turbulence in level flight does not impart sufficient forces upon modern aircraft to cause a crash. It nevertheless imposes a risk of injury to the passengers and crew. There have been hundreds of documented cases during severe turbulence in which unrestrained passengers and crew (without their seatbelts fastened) were "thrown" about the cabin leading to serious injury and death ⁽¹⁾.

There is a special form of turbulence, called windshear (also known as wind shear), which presents a potentially high risk to the aircraft itself, and a particular form of windshear, called a microburst, which has proven catastrophic to aircraft during final approach for landing. Microbursts are especially vexing because they are extremely powerful, localized, and they manifest themselves quickly and without warning. For example, Delta Airlines flight 191, a Lockheed L1011 that crashed at Dallas-Forth Worth, Texas, USA on 2 August 1985, encountered a microburst near the end of the runway less that two minutes after an earlier aircraft landed safely on the same runway without experiencing the microburst. ⁽²⁾.

Microbursts are such a serious concern that modern airports and airplanes are equipped with windshear detection and alert systems that advise air traffic controllers and pilots of potential windshear conditions.

^{1 - Source: http://www.fss.aero/accident-reports/browse_keywords_results.php?cb_key=cb_flt_attendant}

^{2- Source: http://www.ntsb.gov/ntsb/brief.asp?ev_id=20001214X37434&key=1}