Date & Time:
Apr 15, 1966
Type of aircraft:
Lockheed C-130 Hercules
Operator:
Registration:
10304
Flight Phase:
Flight
Flight Type:
Military
Survivors:
Yes
Site:
Plain, Valley
Schedule:
Rivers - North Battleford
MSN:
3590
YOM:
1960
Country:
Canada
Region:
North America
Crew on board:
0
Crew fatalities:
0
Pax on board:
0
Pax fatalities:
0
Other fatalities:
0
Total fatalities:
0
Circumstances:
On a flight from Rivers AFB, Manitoba, to North Battleford, a technical failure occurred on the front cargo door that detached in flight. The crew decided to reduce his altitude and to attempt an emergency landing. The aircraft eventually completed a belly landing in a field located near North Battleford, slid for several yards and came to rest. There were no injuries among the crew while the aircraft was considered as damaged beyond repair. After the accident, the engine number one could not be stopped, probably after being hit by debris.
Probable cause:
The door opened in flight, detached and was later found 15 miles away. The causes were both material failure and maintenance error. The latching mechanism, consisting of four eyebolts, had failed allowing the door to tear off and with it, the top of the fuselage. The n°1 eyebolt tying the door to the fuselage ruptured through over-stressing causing the n°2 bolt to fail as the load was transferred to it. The fact that n°2 eyebolt failed in this manner is strong evidence that the n°1 eyebolt had been overloaded. Laboratory investigation disclosed that the n°1 eyebolt had been cracked for some time; only 2/3 of the cross sectional area was carrying the load at the time of this failure. Analysis disclosed that both the initial crack and the ultimate failure were a result of overloading; also, rough machining during manufacture had helped the crack form. Misalignment during door rigging is strongly suspected as creating the overload.
