Tag Archives: Societé Anonyme Belge d’Exploitation de la Navigation Aérienne

1 September 1953

Sabena Sikorsky S-55 OO-SHA (Sabena)

1 September 1953: The Societé Anonyme Belge d’Exploitation de la Navigation Aérienne (SABENA) began scheduled international passenger service flying the Sikorsky S-55, a commercial variant of the military H-19 Chickasaw. It carried 8 passengers.

SABENA advertisement

For just over three years, since 21 August 1950, SABENA flew mail from Brussels to Antwerp, Liege, and Turnhout using the Bell Model 47D-1.

The Sikorsky Aircraft Corporation S-55 was flown by two pilots in a cockpit placed above the passenger/cargo compartment. The most significant design feature was moving the engine from directly under the main rotor mast to a position at the front of the helicopter. Installed at an angle, the engine turned a drive shaft to the main transmission. The engine placement provided space for a large passenger/cargo compartment. The aircraft was constructed primarily of aluminum and magnesium, with all-metal main and tail rotor blades.

Cutaway drawing of the Sikorsky S-55/H-19/HO4S/HRS. Note the rearward-facing, angled placement of the radial engine.(Sikorsky Historical Archives)

The main rotor consisted of three fully-articulated blades built of hollow aluminum spars, with aluminum ribs. Spaces within the blade were filled with an aluminum honeycomb. The blades were covered with aluminum sheet. The hollow spars were filled with nitrogen pressurized to 10 p.s.i. An indicator at the blade root would change color if nitrogen was released, giving pilots and mechanics an indication that the spar had developed a crack or was otherwise compromised. The main rotor turned counter-clockwise as seen from above. (The advancing blade is on the helicopter’s right.) Flapping hinges were offset from the main rotor axis, giving greater control response and effectiveness. The tail rotor was mounted on the helicopter’s left side in a pusher configuration. It turned clockwise as seen from the helicopter’s left.

The helicopter’s fuselage was 42 feet, 2 inches (12.852 meters). The main rotor had a diameter of 53 feet (16.154 meters) and tail rotor diameter was 8 feet, 8 inches (2.642 meters), giving the helicopter an overall length with all blades turning of 62 feet, 2 inches (18.948 meters). It was 13 feet, 4 inches (4.064 meters) high. The landing gear tread was 11 feet (3.353 meters). The S-55 had an empty weight of 4,785 pounds (2,173 kilograms) and maximum takeoff weight of 7,200 pounds (3,271 kilograms). Fuel capacity was 185 gallons (698 liters).

The S-55’s large clam shell doors provided excellent access to the engine.

The S-55 commercial helicopter and H-19/HO4S and HRS military variants used an air-cooled, supercharged 1,301.868-cubic-inch (21.334 liter) Wright Aeronautical Division 871C7BA1 Cyclone 7 (R-1300-3) 7-cylinder radial engine with a compression ratio of 6.2:1. The R-1300-3 was also a direct-drive engine, but was rated at 700 horsepower at 2,400 r.p.m., Normal Power, and 800 horsepower at 2,600 r.p.m. for Take-Off. The engine incorporated a large cooling fan to circulate air around the cylinders. The R-1300-3 was 49.68 inches (1.261 meters) long, 50.45 inches (1.281 meters) in diameter, and weighed 1,080 pounds (490 kilograms).

SABENA Sikorsky S-55 OO-SHF. (Mike Hooks/Avia Deja Vu)

© 2018, Bryan R. Swopes

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15 February 1961, 09:05 UTC

Boeing 707-329 OO-SJB, Sabena Flight 548. (© Guy Van de Merckt)
Boeing 707-329 OO-SJB, Sabena Flight 548. (© Guy Van de Merckt)
Commandant de Bord Ludovic Marie Antoine Lambrechts, Officier de l’Ordre del Couronne, Chevalier de l’Ordre de Leopold. (1917–1961)
Commandant de Bord Ludovic Marie Antoine Lambrechts, Officier de l’Ordre del Couronne, Chevalier de l’Ordre de Leopold. (1917–1961)

15 February 1961, 09:05 UTC: This Boeing 707-329 airliner, registration OO-SJB, under the command of Captain Ludovic Marie Antoine Lambrechts and Captain Jean Roy, was enroute from Idlewild Airport, New York (IDL) to Brussels-Zaventem Airport (BRU) as SABENA Flight SN548, when three miles (4.8 kilometers) short of the runway at an altitude of 900 feet (274 meters), it pulled up, retracted its landing gear and accelerated.

The airliner made three 360° circles, with the angle of bank steadily increasing to 90°. The 707’s wings then leveled, followed by an abrupt pitch up. OO-SJB spiraled into a nose-down dive and crashed into an open field 1.9 miles (3 kilometers) northeast of Brussels and all 61 passengers and 11 crew members and 1 person on the ground were killed, including the entire U.S. Figure Skating Association team, their families, coaches, judges and officials.

Wreckage of Sabena Flight 548, 15 February 1961.
Wreckage of SABENA Flight SN548, Brussels, Belgium, 15 February 1961.

The cause of the crash was never determined but is suspected to be a mechanical failure in the flight control system:

Having carried out all possible reasonable investigations, the Commission concluded that the cause of the accident had to be looked for in the material failure of the flying controls. However, while it was possible to advance certain hypotheses regarding the possible causes, they could not be considered entirely satisfactory. Only the material failure of two systems could lead to a complete explanation, but left the way open to an arbitrary choice because there was not sufficient evidence to corroborate it.”

The Federal Aviation Administration commented that the most plausible hypothesis was a malfunction of the stabilizer adjusting mechanism permitting the stabilizer to run to the 10.5° nose-up position.

Societé Anonyme Belge d’Exploitation de la Navigation Aérienne (SABENA) was the national airline of Belgium. It was based at Brussels and operated from 1923 to 2001.

The United States Figure Skating Association team, boarding SABENA Flight SN548 at Idlewild Airport, New York, 14 February 1961. From left in front row are: Deane McMinn, Laurence Rochon Owen, Steffi Westerfeld and Rhode Lee Michelson. From left on the bottom: Douglas Ramsay, Gregory Kelley, Bradley Lord, Maribel Y. Owen, Dudley Richards, William Hickox, Ray Hadley Jr., Laurie Hickox, Larry Pierce, Ila Ray Hadley, Roger Campbell, Diane Sherbloom, Dona Lee Carrier, and Robert and Patricia Dineen. (U.S.F.S.A.)
The United States Figure Skating Association team, boarding SABENA Flight SN548 at Idlewild Airport, New York, 14 February 1961. From left in front row are: Deane McMinn, Laurence Rochon Owen, Steffi Westerfeld and Rhode Lee Michelson. From left on the bottom: Douglas Ramsay, Gregory Kelley, Bradley Lord, Maribel Y. Owen, Dudley Richards, William Hickox, Ray Hadley Jr., Laurie Hickox, Larry Pierce, Ila Ray Hadley, Roger Campbell, Diane Sherbloom, Dona Lee Carrier, and Robert and Patricia Dineen. (U.S.F.S.A.)
This February 13, 1961 edition of Sports Illustrated was found in the burned-out wreckage of SABENA SN548. U.S.F.S.A. figure skater Laurence Rochon Owen’s photograph is on the cover. The 16-year-old skater is second from the left in the team photograph, above.
This February 13, 1961 edition of Sports Illustrated was found in the burned-out wreckage of SABENA SN548. U.S.F.S.A. figure skater Laurence Rochon Owen’s photograph is on the cover. The 16-year-old skater is second from the left in the team photograph, above.

SABENA Flight SN548 was a Boeing 707-329 Intercontinental. OO-SJB, Boeing serial number 17624, was nearly a new aircraft. It made its first test flight 31 December 1959 at Renton, Washington, and was delivered to SABENA 15 January 1960. At the time of the accident, it had just 3,038 total flight hours (TTAF).

The Boeing 707 was a jet airliner which had been developed from the Model 367–80 prototype, the “Dash Eighty.” It was a four-engine jet transport with swept wings and tail surfaces. The leading edge of the wings were swept at a 35° angle. The airliner had a flight crew of four: pilot, co-pilot, navigator and flight engineer.

The 707-329 Intercontinental is 152 feet, 11 inches (46.611 meters) long with a wing span of 145 feet, 9 inches (44.425 meters). The top of the vertical fin stands 42 feet, 5 inches (12.928 meters) high. The wing is considerably different than on the original 707-120 series, with increased length, different flaps and spoilers, and the engines are mounted further outboard. The vertical fin is taller, the horizontal tail plane has increased span, and there is a ventral fin for improved longitudinal stability.The 707 pre-dated the ”wide-body” airliners, having a fuselage width of 12 feet, 4 inches (3.759 meters).

The airliner’s empty weight is 146,400 pounds (66,406 kilograms). Maximum take off weight (MTOW) is 333,600 pounds (151,320 kilograms). At MTOW, the 707-329 required 10,840 feet (3,280 meters) of runway to take off.

OO-SJB was powered by four Pratt & Whitney JT4A turbojet engines, producing 15,800 pounds of thrust, each. Its maximum speed is 0.80 Mach (552 miles per hour, or 889 kilometers per hour). It had a range of 4,298 miles (6,920 kilometers).

The Boeing 707 was in production from 1958 to 1979. 1,010 were built.

The cover of the 13 February 1961 edition of Sports Illustrated. (SI)
The cover of the 13 February 1961 edition of Sports Illustrated. (SI)

© 2017, Bryan R. Swopes

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