1957 Begé VARIG Commando crash. The 1957 Bagé VARIG Commando crash, was an aviation accident that occurred on 7 April 1957 at Bagé Airport in Rio Grande do Sul. The accident resulted in the deaths of all forty occupants of the aircraft.

Aircraft 

The Curtiss C-46 Commando was developed between 1937 and 1940 as a transport aircraft for 24 to 34 passengers. During World War II, it was widely used for transporting troops and military material, with over 3,000 units produced. After the war, most were sold by the United States government as surplus to various airlines worldwide, which converted them for passenger and cargo transport. Viação Aérea Rio Grandense (VARIG) acquired 22 Curtiss C-46 aircraft, operating them between 1948 and 1971. Nine aircraft were re-engined, receiving Pratt & Whitney R-2800-83 AM4 engines of 2,100 hp (while the original engines, Pratt & Whitney R-2800-75, had only 2,000 hp) and were renamed Super 46C. The accident aircraft was manufactured in 1944 and received the serial number 30283. Upon arriving in Brazil, the aircraft was assigned the registration PP-VCF.

Accident 

The Curtiss C-46 was scheduled to fly the route Livramento – Bagé – Porto Alegre. The crew consisted of 5 members: pilot Fernando Silva Leandro, co-pilot Antônio Aniceto Silva Filho, radiotelegraph operator Joésio Cruz, and flight attendants Nicanor Ferreira and Dietrich Engl. It carried 35 passengers. After taking off from Santana do Livramento Airport at 08:00, it arrived in Bagé. Around 08:30, it took off towards Porto Alegre. Three minutes after takeoff, the crew declared an emergency to the Bagé Airport tower, caused by a fire in the left engine. During the return to Bagé Airport, the crew fought the fire using the four emergency engine extinguishers. During the first landing attempt, the Curtiss crew was informed that the landing gear had not been fully deployed, which would endanger the crew and passengers due to the risk of fire. Because of this problem, the landing was aborted, and another attempt was made, as the fire seemed to have been controlled and the emergency landing would occur only as a precaution.

Before executing the second attempt, the aircraft lost its left wing and crashed onto the airport runway, exploding shortly after. The crash and subsequent fire killed all the aircraft occupants, despite the rescue teams' efforts to combat the fire.  was one of the passengers on PP-VCF, and his death caused great emotion in Rio Grande do Sul. A journalist, politician, and diplomat, he served as the Secretary of Education of Rio Grande do Sul until his death.

Consequences 

The inquiry concluded that the left engine had not suffered damage, so the fire had originated in the lower wing area between the engine and fuselage. This point was completely invisible to the crew, who, seeing the wing and left engine engulfed in flames, thought it was an engine fire and activated the engine fire extinguishers.

The Curtiss C-46, like many aircraft of its era, was designed to operate in both modern airports and improvised dirt airstrips. Due to rain, the dirt could turn into mud, making landing and takeoff operations impossible. To prevent these problems, many rustic airports or small dirt airstrips received thin layers of gravel and pebbles, which reduced the effects of rain on the dirt. The airfields in Rio Grande do Sul at the time were no exception and also received this road treatment. The investigation commission, based on evidence, discovered that during landings and takeoffs on gravel and pebble-coated runways, the aircraft's landing gear wheels threw gravel and pebbles into the landing gear compartment. The sharp stones could rupture fuel lines (worn by time's action). Made of duralumin, these ducts interconnected the wing fuel tanks. The fuel leaking from these damaged ducts accumulated in the wing (which in early C-46 models did not have drains to expel this leaked fuel) and poured onto the engine exhaust, igniting rapidly. The flames reached the main spar of the left wing, which could not withstand the intense heat, detaching from the fuselage and causing the disaster.

The Curtiss C-46 had always been considered a problematic aircraft due to its poor performance, particularly in single-engine flight (with several airlines replacing the original Pratt & Whitney R-2800-75 engines of 2000 hp with Pratt & Whitney R-2800-83 AM4 engines of 2100 hp), its high fuel consumption, and frequent fuel tank leaks. Several aircraft experienced fires or mysterious crashes until the fragility of the fuel line system, made of duralumin, was discovered. The lack of wing drains (corrected in later versions of the aircraft) caused an accumulation of fuel leaking from these ducts, turning the wing into a ticking time bomb that could be ignited by a spark at any moment.

After the accident, Varig installed drains in the wings of its Curtiss aircraft and replaced all duralumin ducts with similar stainless steel ones. The runways at Bagé Airport were paved with concrete only in the mid-1960s. The last Curtiss C-46 aircraft of Varig were replaced in 1971 by the Hawker Siddeley HS 748.

References

Bibliographie 

 SILVA, Carlos Ari Cesar Germano da; O rastro da bruxa: história da aviação comercial brasileira no século XX através dos seus acidentes; Porto Alegre Editora EDIPUCRS, 2008, pp 190–193.

External links 

 Accident data on the Aviation Safety Network site (in English)
 Accident data on Plane Crash Info site (in English)
 Accident data on Air Disaster site (in English)
 Accident data on Desastres Aéreos site

Aviation accidents and incidents in Brazil
Aviation accidents and incidents in 1957
Aviation accidents and incidents caused by in-flight fires
1957 in Brazil
Accidents and incidents involving the Curtiss-Wright C-46 Commando