Yak-42 Crash Near Verbovichi (CCCP-42529)

Incident Overview and Crash Details During an enroute flight from Leningrad to Kiev, the crew of a three-engine Yak-42 was cleared to descend from 9,000 to 7,800 meters to avoid a thunderstorm area. Minutes later, the aircraft entered a dive. During the uncontrolled descent, the aircraft lost several elements and partially disintegrated before crashing at a speed of 810 km/h into fields and wooded areas. A large crater was found at the point of impact near the village of Verbovichi, with debris scattered over an area of 22.7 km² (6.5 km long and 3.5 km wide). The accident was not survivable. ## Probable Cause and Maintenance Findings The official investigation determined that the crew lost control of the airplane after the jackscrew connected to the stabilizers mechanism failed due to abnormal wear and a structural imperfection of its mechanism. This failure caused the stabilizers to move down and remain blocked in the down position. Despite several attempts, the crew was unable to regain control of the aircraft. Aerodynamic forces caused several elements of the airplane to break off as they exceeded their certification limits. ## Maintenance Program and Fleet Impact Investigations revealed that it was not possible for those in charge of Yak-42 maintenance to detect the jackscrew's abnormal wear because of an incomplete maintenance program. Similar problems were found on other Yak-42 aircraft, and the type's certificate of airworthiness was suspended during the investigations. Following modifications and updates, the Yak-42 returned to service at the end of 1984.