Date & Time:
Dec 4, 1952 at 1752 LT
Type of aircraft:
Lisunov LI-2
Operator:
Registration:
CCCP-L4661
Flight Phase:
Flight
Flight Type:
Scheduled Revenue Flight
Survivors:
Yes
Site:
Plain, Valley
Schedule:
Dudinka – Yeniseysk – Krasnoyarsk
MSN:
46 01
YOM:
11
Flight number:
SU688
Country:
Russia
Region:
Asia
Crew on board:
5
Crew fatalities:
0
Pax on board:
14
Pax fatalities:
3
Other fatalities:
0
Total fatalities:
3
Aircraft flight hours:
2670
Circumstances:
The airplane left Yeniseysk Airport at 1655LT bound for Krasnoyarsk. Thirty minutes later, while cruising at an altitude of 1,800 meters by night and in good weather conditions, the crew encountered technical problems with the left propeller that was over speeding. For unknown reason, the crew was unable to feather the propeller and took the decision to return to Yeniseysk. Due to drag, the aircraft lost height and thirty minutes later, at a speed of 130 km/h, it hit tree tops and crashed in a wooded area located 25 km south of Yeniseysk Airport. Three passengers were killed while 16 other occupants were injured. The aircraft was destroyed.
Probable cause:
Failure of the pressure switch on the left-hand drive regulator in flight, which caused the propeller to overspeed. A contributory factor was the crew who failed to set the nominal mode of operation on the right engine immediately after the start of the descent, using full power on the right engine with delay, which caused the aircraft to lose altitude rapidly. Despite good visibility due to moonlight, the crew failed to attempt an emergency belly landing in a suitable terrain.
