Aeroflot Flight 8641

Aeroflot Flight 8641

Aeroflot Yak-42, similar to the one that crashed
Accident summary
Date	June 28, 1982
Summary	Jackscrew failure due to metal fatigue; design flaw
Site	Near Mozyr, Soviet Union
Passengers	124
Crew	8
Fatalities	132 (all)
Survivors	0
Aircraft type	Yakovlev Yak-42
Operator	Aeroflot
Registration	CCCP-42529
Flight origin	Pulkovo Airport, Leningrad, Russian SFSR, Soviet Union
Destination	Kyiv-Zhuliany International Airport, Kiev, Ukrainian SSR, Soviet Union

Aeroflot Flight 8641 was a Yakovlev Yak-42 airliner on a domestic scheduled passenger flight from Leningrad, Soviet Russia, to Kiev, Soviet Ukraine. On June 28, 1982, the flight crashed near Mozyr, Belarus, killing all 132 people on board. The crash was the first and deadliest one involving a Yakovlev Yak-42, as well as the deadliest aviation accident in Belarus.

The aircraft involved in the accident was a Yakovlev Yak-42 registered to Aeroflot as CCCP-42529. The aircraft made its maiden flight on 21 April, 1981. At the time of the accident the aircraft had only 795 airframe hours and 496 cycles (one cycle equals one takeoff and landing).

There were eight crew members, with four cockpit crew and four flight attendants.

The cockpit crew consisted of the following:

The flight attendants were as follows:

The aircraft took off from Pulkovo Airport at 9:01 GMT, after stopping to pick up passengers who were running late. At 10:45 the aircraft entered the zone of Boryspil air traffic control center. The crew started to prepare for descent at 10:48:01. At 10:48:58 the crew contacted the air traffic controller and requested to land early. The controller instructed them to remain in a holding pattern at 7800 meters. The crew confirmed the flight path and no further communications were heard from flight 8641. At 10:51:20 the autopilot gradually brought about stabilizer angle of up to 0.3° into the descent for landing. Suddenly at 10:51:30 the stabilizer angle sharply increased, exceeding the 2° limit. The sudden change resulted in an overload of 1.5 g, but the autopilot adjusted the wheel and controls to lower it to 0.6 g. After the pilots pulled back on the yoke to level out the plane the autopilot switched off after three seconds, putting the aircraft into a steep dive. While struggling to maintain control the pilots pulled on the control columns, but the plane rolled 35° and went into a dive of 50°; at 10:51:50 and enduring well over 2 g forces the aircraft lost control and went into a dive, disintegrating in mid-air.

The cause was discovered to be a failure of the jackscrew mechanism in the aircraft's tail due to metal fatigue, which resulted from flaws in the Yak-42's design. The investigation concluded that among the causes of the crash along with poor maintenance was the control system of the stabilizer not meeting basic aviation standards, as for the official cause of the crash; "The spontaneous movement of the stabilizer was due to disconnection in flight of jackscrew assembly due to the almost complete deterioration thread 42M5180-42 nuts due to structural imperfections in the mechanism." As a consequence of the accident, all Yak-42s were temporarily withdrawn from service until the design defect was fixed in October 1984.