USAF B377 - A lesson of courage over the Pacific ! (en)

Article original en français

Boeing 377 Stratocruiser. Civil transport aircraft derived
Bombers B-50 and B-29 of World War II.
Note the size of the propellers and their proximity.

 Occurred fifty years ago, this story remains to this day a lesson in courage and airmanship. It shows determined pilots, facing a plane inventing them problems more and more severe in the night, in the middle of the Pacific Ocean. To this succession of damage, an extraordinary series of rapid and appropriate decisions.




After World War II, Boeing plans its fate bombers B-50 and B-29 and decided to launch a safe and comfortable civilian aircraft. Recipes that have been proven were taken by Boeing and the Boeing 377 was born in 1947. A little larger than an Airbus A320, this aircraft was capable of carrying a hundred passengers in conditions of comfort that is much higher than what we see today. Passengers had bars, lounges and beds for rest during long flights just under 500 km/h. Until the release of the Boeing 707, it will remain as a reference plane for the long haul.

 
The Boeing 377 had four piston engines Pratt & Whitney R-4360. Each had 28 cylinders distributed on 4 stars staggered to allow proper cooling. With 71.4 liters, each engine was able to send 4,300 horsepower in its propeller shaft. A turbocharger driven at 6.374 times the engine speed powered the engine. At the same time, a reducer entailed the propeller about a third of the speed of the motor.Engine P & W R-4360 Wasp Major. Its 71.4-liter engine are 4360 cubic inches, hence the name.From the start of operations, the engines are very finicky. When a plane stays at night in parking, central oilpan oil leaked down to the lower pistons. If the segments are not perfect, it flows even in the huge combustion chambers. At startup, the passengers remained unconvinced by the impressive black smoke ejected from their aircraft engines.

On August 8, 1957, a Boeing 377 took off from Los Angeles to Honolulu. The crossing to the south west lasts more than 10 hours to go 3700 km above the water. The flight is organized on the U.S. Navy that gives the name C-97 in the same plane. In addition to the 10 crew members, 57 passengers are on board. There are military families and a dozen young children.Once it reaches 16,000 feet, the aircraft is stabilized at cruise altitude on autopilot and the navigator is the crew member who works the most. He ensures engines and parameters of the cabin while the copilot constantly monitors his flight instruments.The plane had just passed the middle of his route when all the occupants were alerted by a great roar coming from the left. On the board, the engineer sees the engine 1 rpm indicator needle racing. At 3,800 rpm, the blade extremities of the propeller exceed the speed of sound! At every moment, the propeller may break and come tearing the cabin of the aircraft.

The current aircraft propellers are equiped with a mechanical stop to prevent the propeller to take a small pitch back when the plane is cruising. Indeed, in case of engine failure, the first movement of a propeller is to return to the fine pitch. Thereafter, another mechanism by feathering. This recoil to the fine pitch is not desirable. The propeller overspeeds and creates a strong yaw moment. In addition, it is necessary to make it a more important mouvement to be feathered.

Immediately, the captain reduced the engine number 1 throttles and mixture then pressed the button to turn the propeller feathered. At the same time, he pulls on the yoke to reduce the speed and asks the first officer to extend the flaps to position 55%. To reduce the speed of the plane is the only way available to calm the propeller especially since it does not seem to turn feathered. The plane is so unbalanced by the drag generated that the pilots reduce all engines throttles. For some long time, they soar into the sea while trying to solve the problem.

While the continuous roar still tearing the night, engine 1 propeller regulator oil quantity dipstick falls to zero. This is very bad news. It means that it is possible to feather this propeller but have to live with. The speed of the plane decreases and full power must be applied on the remaining engine to stay in the air. With this configuration, it is no longer possible to reach the destination, neither to go back. The sea-landing is the most likely prospect.

While ensuring the performances of engines still active, the crew decided to sacrifice the number 1 engine. Its lubricating oil is removed. Indeed, these engines consume large quantities of oil provided by an external tank. By cutting this arrival, it is possible to eventually cause engine seizure. A propeller not turning has less resistance than a propeller that is lead by the relative wind.While the engine consumes the residual oil, passengers are equipped for a sea-landing. At the station, the navigator remakes its calculations: it will not be possible to reach the destination. It missed 30 minutes of fuel. The captain decided to close as possible to the destination and put the plane into the sea when it's light. The co-pilot launches distress messages to the HF radio.Suddenly, a loud explosion was heard on the left side. The engine without oil seized. However, it blocked so brutally that the inertia of the propeller broke the engine shaft and the propeller started crunching harder. Nothing prevents it from turning faster.

The mechanic looks and from his window he sees the propeller hub turning red. The temperature is such that this part, that connects the blades begins to melt. From minute to minute, the crazy propeller will break.The captain takes a decision absolutely unique in the history of aviation. He cuts the number 2 engine and propeller turns feathered. The plane is almost in the air, but the captain is adamant : it tilts 40 degrees right the wing with engines 1 and 2 closed. For passengers, it becomes clear that the plane is in distress.

A minute later, the engine one propeller snatch and pulls sharply to the right. It breaks a blade of engine number 2 then rips the top of the cabin! If the engine 2 was turning, the imbalance caused by the loss of one meter blade would have been sufficient to generate intense vibrations that would have broken the wing. If the plane had not been tilted 40 degrees, the massive propeller would have torn the cabin through.Crew precautions paid. By cons, both engines are lost on the same side. In addition, the engine caught fire and one burning like a torch for 8 long minutes before finally extinguish hydrocarbon fault.The aircraft is stabilized to 5,500 feet and the pilots struggle to keep it on the track. If any of the remaining engines shows the slightest sign of weakness, it's the crash in the middle of the ocean.

A Stratocruiser cockpit

The day begins to rise, revealing a vast desert in all directions. The ground and in the air, are preparing emergency. Another transport plane that took off from California one hour before the Boeing 377 turned around and started looking for it to intercept and escort as far as possible.

The first good news of the day is announced by the navigator : the aircraft flies slower and has two engines less. Therefore, consumption per unit distance is slightly lower and there is still a chance to reach the Hawaii archipelago. To give every chance, the crew opens the door of the aircraft and everything that is not vital is thrown overboard. Mail, cargo, baggage, personal effects go into the sea without any complaints from passengers. By cons, opening the door causes additional drag and the plane did not have enough energy and begins to lose altitude. It is only 50 feet when the door is finally closed.The plane takes a little altitude and speed increases. The navigator comes with a new estimate that was chiling: the next airport, Hilo, is 5:00 flight away but there is only 5:04 fuel remaining. The arrival at destination seems increasingly compromised. The slightest headwind that can stand up to condemn the plane to land.


Again, the pilots do not let themselves down. They decide to flying raze to avail the ground effect. It reduces induced drag. In a span of height, induced drag down nearly 14% and saves fuel. For cons, the procedure is not without danger. The aircraft has two engines inoperative and is very difficult to control by pilots who take turns at the helm. The slightest mistake and it can impact the ocean more than 1,000 miles from its destination. After several trials, pilots discover the best flight altitude for their plane is 100 to 125 feet. The Boeing 377 has a wingspan of 143 feet.The passengers are all the time attached to their seats and alert. They know that at this height, there will be no warning before a possible sea-landing. Everyone must be prepared to save every minute. To further save fuel, the pilots shut down the air conditioning system. 

When the sun rises, the cabin temperature rises and exceeds 43 degrees while the moist air becoming more and more unbearable. Life jackets keep you warm and make sweat but there is not any question of removing them.The hours pass like centuries, then the good news comes. A tail wind gets up and gives the aircraft 37 km/h more. Then, two other planes intercept and escort the Boeing 377 remotely. In case of a sea-landing, more rafts and emergency equipment will be launched.Suddenly, white streaks appear on the horizon. Many ships of the U.S. Navy positioned themselves on the road to the damaged Boeing to lend it assistance. A little later, the earth begins to loom on the horizon. On the plane, the relief for everyone.

After gaining a little altitude, the aircraft turns direct approach on a 2,000 meters runway. The flaps are extended, the speed is reduced and the copilot down the landing gear lever. First green light comes on, then a second and that's all. The day is not over yet! The left main landing gear did not extend. 
- You have enough fuel to make a go-around, announces the FE

The captain hesitated a moment. His desire to end this nightmare is very strong, but it did not save the plane of the waves to come crashing down on the runway with a probable loss of human lives. 
It takes the control of the remaining engines and pushes forward. The co-pilot up the landing gear and the aircraft flew over the airport and the altitude geting away.

Photo taken from the ground during the go around at Hilo. One meter of engine 2 blade and the entire engine 1 propeller are missing. 

Mechanics struggle with the landing gear emergency system. Engine 2 which houses the landing gear is twisted and the door does not open. In their efforts, it is torn and the gear is down and locked in a safe position. 
A few minutes later, the plane made ​​a very nice landing on the runway. It remained 30 minutes of fuel.  

Never an airliner had made a so spectacular recovery.
  
(Translated from the french original text by Amine MECIFI)