44 Years ago today: On 14 April 1976 an Yacimientos Petroliferos HS-748 crashed near Cutral-Có, Argentina following the inflight separation of a wing, killing all 34 occupants.

Date: Wednesday 14 April 1976
Time: 16:25
Type:
Avro 748-105 Srs. 1
Operator: Yacimientos Petroliferos Fiscales
Registration: LV-HHB
C/n / msn: 1540
First flight: 1962
Total airframe hrs: 25753
Cycles: 24130
Engines: Rolls-Royce Dart 514
Crew: Fatalities: 3 / Occupants: 3
Passengers: Fatalities: 31 / Occupants: 31
Total: Fatalities: 34 / Occupants: 34
Aircraft damage: Destroyed
Aircraft fate: Written off (damaged beyond repair)
Location: 35 km (21.9 mls) N of Cutral-Có , NE (   Argentina)
Phase: En route (ENR)
Nature: Domestic Non Scheduled Passenger
Departure airport: Rincón de Los Sauces Airport, NE (RDS/SAHS), Argentina
Destination airport: Cutral Airport, NE (CUT/SAZW), Argentina

Narrative:
The Avro 748 aircraft, named “Ciudad de Corrientes”, was making a staff-transfer flight for the Yacimientos Petroliferos Fiscales (YPF) State Enterprise. It began in Cutral-Có at 14:00 and the aircraft landed 40 minutes later on a Company landing strip in Rincón de Los Sauces. The aircraft took off at 15:55 for Cutral-Có again with 31 passengers and 3 crew.
At 16:23 the crew contacted Cutral-Có and asked for information on the local state of the weather and estimated landing at 16:33. At an altitude of about 4000 feet the starboard wing failed, followed by separation of the starboard tailplane. The remainder of the plane corkscrewed and crashed.

Probable Cause:

PROBABLE CAUSE; “The accident was the result of detachment of the right hand wing in normal flight, through structural failure of the wing in the area between stringers 3 and 12 and in the area of the engine outer rib.
Within the area indicated, one may identify among the origins of the fatigue the reinforcing plate, and especially, the holes in it for rivets.
The cause of these fatigue cracks, since the material of which they were made was satisfactory, must be attributed to stress concentration in the area concerned due to geometry of the design, these cracks becoming critical sooner than had been estimated. The cracks remained undetected and became critical because the manufacturer’s inspection programme for the area concerned was insufficiently precise and made it possible for the operator not to detect and correct them in time.”