The C-141, Lockheed's High Speed Flying Truck
by Harold H. Martin
This Plane Can Hack It
LESS THAN FOUR YEARS after the Golden Bear, the first operational C-141, went into squadron service at Travis, a ship of the StarLifter fleet, now grown to 284 planes, passed "the millionth hour in the air. The plane by now had proved it could do all the work it was designed to do. It had lifted thousands of tons of general cargo over millions of miles to resupply U.S. troops abroad. It had transported the troops themselves-up to two brigades of Army combat soldiers, with all their battle gear -in fast "Big Lifts" to Vietnam, Korea, and Germany. With its cabin fitted out with stanchions to which litters could be hung, it had brought back the sick and wounded, transporting them in nine hours to hospitals in the States. It had begun aerial service to the Deep Freeze scientists at the South Pole, becoming the first fanjet to land on the Antarctic ice. In an incredible 23,000-mile round trip, a StarLifter had flown from Travis to Vietnam to New Zealand to Travis in two and one half days, carrying troops to Vietnam and supplies to Christchurch for the Polar explorers. And twice a week, on regular scheduled flights, it had girdled the world on grinding five-day trips to serve U.S. Embassies abroad. In the words of Walter L. Krause, Star-Lifter historian, "the C-141 gives us a flexibility that is the core of a new national strategy. It can go anywhere, carry out any mission, in war, or peace. The plane, in short, can hack it."
Nobody knows this better than Colonel Vere Short, who before being assigned to Charleston as deputy commander of the Joint Test Force for the C-5 had put in 6000 flying hours in the StarLifter-more flight time than any other C-141 pilot. A veteran pilot with 26,000 hours of accident-free flight on his record, Colonel Short was with the first operational MAC StarLifter squadron, the 44th, when it started flying out of Travis in 1964. Thereafter he was constantly in the air between the U.S. and Southeast Asia and Europe, on routine hauls as well as troop exercises such as Eagle Thrust and Reforger. He was aircraft commander on the StarLifter when the fleet passed its millionth hour in the air-quicker than any other plane had reached that milestone. "They haven't built a plane yet that approaches the StarLifter's record, but the C-5 has the potential," he said.
Though the first years of StarLifter operation were on the whole triumphant, they were also marked by tragedy. In September 1966, at McChord Air Force Base, ground crewmen emptied a wing tank of fuel so that instrument technicians could fix a faulty fuel-quantity indicator. Some flaw in their test equipment caused an electric spark in the empty but still fume-filled tank. The wing exploded and three men were killed.
The following spring, at Da Nang Air Base, Vietnam, a tired StarLifter crew came in on a foggy night after a five-and-a-half-hour flight. Under ground control, the landing was smooth, on one of two parallel runways, and the pilot, after roll-out, turned off on the taxiway. There, after receiving, or thinking he had received, clearance from the Vietnamese controller in the tower, he turned off the taxiway to cross the other runway, headed for the ramp. A Marine jet fighter, taking off loaded with eight 750-pound bombs, struck the StarLifter just aft of the copilot's seat. The two Marine pilots punched out in time, their ejection seats blasting them to safety, but in the tremendous explosion that followed, only the loadmaster on the StarLifter survived.
A month later, at Cam Ranh Bay, tragedy struck again. Here the runway is 7000 feet long and the climb-out is over the sea, enough flying room for the most heavily loaded StarLifter. On this flight, bound stateside with a cargo of broken machinery and empty cargo pallets, the copilot, who was on his orientation ride in the MAC system, was in the pilot's seat. The aircraft commander who was checking him, an outstanding pilot of great skill and experience, was in the right-hand seat. Here, functioning as copilot, he ran with laconic professionalism through the six items of the line-up check list. "Check completed," he said, and nodded to the pilot.
As the pilot opened the throttles the plane surged forward, then seemed suddenly to slow; it seemed to take a long time to come to takeoff speed, though the instruments showed nothing wrong and there was plenty of runway still to go. Finally at 125 knots the AC called, "Go." The pilot hauled back on the yoke, and the plane began to climb. Slowly it lifted its 230,000 pounds up to 75 feet, to 100, as it passed over the beach. Then, almost imperceptibly, it began to settle.
"This bird is not going to fly," the pilot declared.
"I'll take her," the AC said. He grabbed the yoke and felt the mushiness of the controls. "Something's wrong," he exclaimed. "Tell the tower we're coming back. Emergency."
"You want the gear up?" the pilot asked, reaching for the handle.
"It won't make that much difference," the AC replied.
There was a bump, and the stick shook.
"Feel the shaker?" the AC asked. His voice was puzzled. The shaker does not come on until the plane approaches stalling speed, and the air speed indicator was showing 140 knots, which was normal climb-out speed.
The pilot, looking to his left to change the wafer switch and call the tower, saw something which told him that they had not felt a shaker and they would never make the emergency return. Ten feet below, shining in the taxilights, were the rippled waves of Cam Ranh Bay. The bump they had felt had not been a stall warning. It had been the landing gear striking the wave tops. An instant later the plane went in, flat, with its left wing a little low. It broke on impact and the pieces were flung along its track for half a mile.
Deep beneath the water the copilot fought clear of the shattered cockpit, and struggled to the surface. The crash-position indicator, flung free of the wreck, was beeping its electronic "Here I am. Here I am." There were lights on the shore and boats were putting off. The pilot clung to a floating pallet and rested. Near him, a badly wounded loadmaster floated on a half-filled water can. In the wreckage of the plane, the AC, the two flight engineers, the navigator, and another loadmaster had drowned.
Long afterward, in his office at Scott Air Force Base, the pilot, Major Rodney Williams, explained what had happened. Set into the wings of the StarLifter are huge panels, known as spoilers, which can be thrust into the slip stream to act as air brakes. They are only used when the plane is on the ground. When set at "Auto Land," they deploy automatically when the wheels touch and spin up to a certain speed, thus helping to slow the aircraft in its landing roll. To keep this from happening on takeoff, the spoiler select-switch must be set at "Rejected Takeoff." This prevents their opening accidentally, but permits the pilot to actuate them if he must abort the takeoff roll. In running the line-up check list, the aircraft commander had left the spoiler switch in "Auto Land." As the plane gathered speed, the spoilers deployed and the plane, with its air brakes on, could not climb.
"We could have made it if we had known what was wrong," Major Williams said. "The plane has flown with the spoilers deployed. But you have to know they are out. Then you can pull the nose up and the plane will keep flying, for it has power enough to overcome the drag. But we didn't know."
Williams, profoundly thankful that his life was spared, has spent his career since pushing the cause of safety, and is now Safety Officer at MAC headquarters at Scott Air Force Base. He learned two things, he says, from the Cam Ranh Bay crash. The man in the left-hand seat is responsible for the plane and the lives of the men in it. He must check and double-check and triple-check every safety item on the preflight lists. He also insists that airplanes be so designed that they make it almost impossible for the pilots or copilots to overlook some safety item. As a result of the Cam Ranh Bay experience, for example, the "Rejected Takeoff" position has now been wired into the green takeoff light. And both pilot and copilot must check the spoiler switch.
After more than two million hours of flying time, the three described are still the only fatal accidents involving a Star-Lifter airplane. There have, of course, been some incredible near misses, in which only superb airmanship by highly trained crews, plus the grace of God and the ruggedness of the aircraft, prevented tragedy.
Not only Major Williams but his associates on the MAC headquarters staff, in Standardization, Operational Requirements, and Maintenance, keep up a lively interest in and make a profound study of all accidents, both major and minor, that involve MAC aircraft. Many of them are unavoidable, of course. The pilot landing on a darkened runway on a moonless night could hardly be blamed for hitting a horse while traveling at 100 knots on his landing roll. Nor could the Dover Air Force Base pilot, on a local check flight over the Eastern seaboard, be gravely faulted for getting a buzzard through his radome. Relatively few incidents derive from flaws in the aircraft itself, though there have been some, which will be described later. So far, however, the ruggedness of the airplane, rather than its frailties, has been its most distinguishing characteristic. One StarLifter, for example, arrived at Eilson Air Force Base in Alaska carrying embedded in its right wing a sizable section of treetop, picked up shortly before when its pilot had gotten too low on the glide path in an attempt to land at nearby Elmendorf.
"This shows you how tough the airframe is," said Major Rit-ter in the Standardization office at MAC. "If it had been a piston-engine plane, that would have been all she wrote. He'd have rolled it up into a ball of aluminum."
Another StarLifter demonstrated its ruggedness in a tricky cross-wind landing, or attempted landing, at Cam Ranh Bay. Coming down through heavy rain on a ground-controlled approach, it had just reached the magic zone and was about to round out when the ground controller, in some excitement, told the pilot he was left of the runway and should pull up and go around. The pilot attempted to pull up, but the loaded plane kept going down at a sink rate of about 580 feet a minute, which was more than it was built to stand. It hit the ground crosswise, short of the runway, and bounced high in the air. The pilot skyballed it and kept going. After flying around a while to calm his nerves, he made an uneventful landing. The incident was dutifully written up on the plane's 781 sheet, but since no overt sign of damage was immediately visible, and the plane seemed to be handling all right, the pilot was permitted to fly on to his next stop at Da Nang. En route the plane began to vibrate in a disturbing manner and the crew, not wishing to take a sick bird back into Vietnam, headed for Clark Air Force Base in the Philippines. There a more careful inspection showed that the hard landing had jolted the gear pod loose from the fuselage on the left side, and that the fuselage itself was so badly warped that the belly of the aircraft sagged down like a pregnant guppy.
Captain Charles Jenkins, in the office of Operational Requirements at MAC headquarters, believes that most accidents and incidents involving aircraft are due to Murphy's Law. It is not very easy, for example, to put a StarLifter's engines into reverse thrust, a braking process employed, like the spoilers, only when the aircraft is on the ground. To do this, the throttles must be pulled back to a definite "Stop" point, and then lifted, and pulled back a few inches further to reverse the thrust. It was discovered, however, that pilots were inadvertently doing this in flight when the situation called for a quick slowdown.
"In combat drop exercises," Captain Jenkins explains, "we fly these big ships in trail, three ships in a line, twenty-two hundred feet apart. It's a touchy formation when you are moving at four hundred and fifty or five hundred knots, and it calls for rapid acceleration or deceleration to maintain your position. So what's been happening is, some pilot would suddenly realize he was coming up too fast on the T-tail in front of him and he'd yank back too hard on the throttles, and they'd pop up over the 'Stop' and into 'Reverse Thrust,' and he'd be hanging there in the sky with all his engines idle and nothing pushing him. He shoves everything to the firewall as soon as he realizes what's happened, of course, but on a few occasions, the thrust mechanisms wouldn't close. They stayed in reverse."
So far, nothing worse than a few moments of sheer terror have been caused by this miscue. One pilot, with masterly airmanship, even brought his StarLifter down on a 4500-foot emergency strip at Baker, Oregon, with three thrust reversers braking him- a remarkable one-engine landing. The threat of disaster is so great, however, that both Lockheed and the Air Force have labored over a fix that will make the thrust reversers Murphy-proof.
Some spectacular incidents in which the StarLifter has figured were due to those gremlins known as "unk-unks"; the unknown unknowns that beset every new aircraft until time and experience reveal ways to fix them. In its earlier days, for example, the C-141 had the startling habit of suddenly coming unzipped -its pressure-door latches giving way at high altitudes, causing a sudden decompression.
This is disconcerting enough when the plane is a cargo ship carrying no one but crewmen who are trained to handle such emergencies. They go on emergency oxygen immediately, as the ship drops down to a low flight level and heads for the nearest land. It is even more disconcerting when there are troops aboard. In a military aircraft the passengers ride backward, facing the tail, and to them a sudden decompression can be alarming in the extreme. The pressure door blows with a bang and a roar, the petal doors carry away, as they are designed to do, and the trooper awakes from sweet dreams of home to find the air sucked from his lungs, a cold gray cloud of condensed moisture swirling around his head, and his baggage, which was stowed on the after ramp, whirling away toward the ocean 30,000 feet below, at which he finds himself staring through a gaping opening in the tail.
One StarLifter to which this happened landed at Wake Island with no damage to the troops more severe than one man's ruptured eardrum. Another incident could have been fatal except for the redundancy of the StarLifter's safety systems. The pressure door, as it blew upward into the after hayloft, was slammed against the lines carrying the hydraulic fuel that activated the elevators and rudders. One line was severed, one damaged; the third was untouched, however, and by keeping up the pressure in the one good line, the aircraft could be controlled.
Fortunately, StarLifters don't blow out their pressure doors anymore. The pressure-door latching system worked all right when it was properly serviced, according to Major Bill Backuss of MAC, whose specialty is maintenance, but it was too complicated for the average Air Force mechanic. It required a blue-ribbon team of maintenance specialists to keep it aligned properly, and this, of course, the Air Force could not provide at all the isolated fields where the StarLifter puts down.
Temporary fixes were installed, and a simpler, stronger system was designed with forty-five fewer parts. Now as the planes go down to Robins Air Force Base in Georgia for their scheduled IRAN-Inspect and Repair as Necessary-the simpler system is installed.
Most of StarLifter's early problems, according to Victor Moore, a civilian maintenance expert at MAC headquarters, grew out of the designers' battle to keep down weight. A spoiler arm that sometimes breaks when the spoiler extends into the full pressure of the slip stream, a wheel that shows a tendency to crack: these, Moore believes, are the result of the engineers' trying to trim off every extra ounce. The cure is usually simple enough- add the needed weight, and strength. This is not always the solution, however. Laminated control surfaces are very light, and strong, and adding weight would not necessarily insure their strength. The secret lies in bonding the surface metal to the inner core, in an absolutely perfect junction of metal and plastic honeycomb. If even the tiniest airspaces are left under a flexing surface, water seeps in, freezes at high altitudes, expands, and forces a separation between skin and core. Delamination begins.
It it, of course, highly disconcerting to have a control surface start peeling off in flight. Major Tom Fournier, in MAC maintenance, recalls one such incident. The plane was climbing out heavily loaded, bound for Europe over the North Atlantic. As it passed through 30,000 feet at a speed of Mach .7, it began to vibrate violently. The heavy shaking lasted about twenty seconds and then steadied down to a slight but unusual quivering. The crew tried to find out what was happening, without success until the navigator climbed up on the stool from which he took his celestial bearings and peered at the tail through his sextant. To his considerable agitation he noted that the elevator looked as if mice had been nibbling at the trailing edge, and as he watched, small pieces continued to carry away. He advised the aircraft commander, who made a cautious 180-degree turn and immediately headed for home.
Backuss and Fournier agree with Victor Moore that problems such as these are the direct result of the plane designers' battle against weight, and they probably will cause more minor problems that will be headaches to the maintenance crews in the future. However, as Victor Moore points out, "Maintenance people are pessimistic by nature, and we certainly don't want to give the impression we are unhappy with the C-141. It is a terrific airplane, operating now at about 95 percent reliability, as compared to the 80 or 90 percent we are used to. The Lead, the Force, and the Combat Pacer programs have taught us what to expect. Once these fixes are made, it should be a great performer for years to come. When you design a plane for so many different missions-troop carrier, cargo carrier, hospital plane, para-drop, cargo drop-you are bound to have some problems. But none so far have been serious enough to ground the plane, or interfere seriously with its missions."
Fixes for bugs that show up long after the plane has finished its test-and-development stage technically are the responsibility of the Air Force logistics command. In the gigantic maintenance hangars at Warner Robins Air Force Base near Macon, Georgia, StarLifters can be completely disassembled, cleaned, inspected, retrofitted with whatever newly designed part or system is required, and put back together again. Lockheed, however, never loses interest in a bird it has built. It maintains field representatives all over the world-skilled men like Marv Donegan at Yokota, Beecher Lockhart at Elmendorf, Hank Fisher at Clark in the Philippines, and Jack Payne at Rhein Main. Their job is to give all the technical help they can to the Air Force if any problem should arise in the field, to call on the Company if more engineering skill is needed, and to send back to Lockheed-Georgia full reports on any StarLifter function that proves unsatisfactory.
The fact that a StarLifter lost some skin off its tail at thirty thousand feet over the Atlantic Ocean was of profound interest, for example, to L. L. Jackson, back at Lockheed-Georgia. A short, bespectacled man with a stubby gray crew cut and a serious attitude toward his work, Jackson was the chief Quality Control Inspector on the C-141, as he is now on the C-5. It was the job of the 175 inspectors working under him then (he has 350 now) to check every part and piece that went into the aircraft, testing it as it came from the fabricating shops to see that it had been properly heat-treated, processed, and milled to exact dimensions and specified strength. Then, poring over detailed drawings of the assembly process, he followed, step by step, the process of putting the plane together. It was naturally of concern to him that a plane he had once inspected had slipped by him carrying a faulty piece of workmanship.
"Bonding," he says, "is the hardest thing to inspect because you can't see it and you can't feel it, and you can't tear the piece apart to inspect it. X-ray is a good tool, and so are supersonics, but one of the best inspection instruments is still the human ear. The old coin-tap method. You tap a coin over the entire surface and you can tell by the difference in sound where you've got a void. Or you can take an occasional sample from the Autoclave and peel it to see if your heat is right and your pressure is right and you are getting a good bond. That's the only way you can control it-by controlling your processes. Your metal has to be absolutely smooth and clean and grease free. You can't even have a fingerprint on it or it will ruin your bond. That's the reason all the men you see working at the Autoclave are wearing white cotton gloves."
Nothing is too small for Jackson's sharp-eyed inspectors to pass by. On the desk in his balcony office overlooking the vast assembly floor, there is a piece of metal about half the size of a postal card. To the layman it is polished to mirror smoothness. To the inspector who found it, already installed in a plane, it is as pitted as the surface of the moon-the result of a minute error in the chemical milling process by which metals are eaten away to an exact thickness.
"It seems unimportant," says Jackson, "because the little pits in that metal are tiny as a pinpoint. But we've learned that it's in little places like these that cracks and corrosion start. So we had to trace that piece back to its source and check the chem-mill process and find out what was wrong. You can't let little things like that slip by. But you've got to have tough, honest inspectors to find them and report them."
Jackson spends roughly half of his time down on the assembly floor, keeping an eye on his inspectors. "I had an inspector once who'd been an old-time barnstorming pilot, and he was a tough inspector. He told me something I never forgot. He said, 'Jack, if you want to know whether a man is a good inspector or not, look at his hands at the end of the workday. If he hasn't got blood on his fingertips, fire him. If he's bleeding, he's doing his job. He's reaching back in the hidden places feeling for the cotter keys to see if they are in place.'
"That's the way my people work," Jackson said. "They touch the hardware. They feel for the cotter keys. They get back in the dark places with a mirror and flashlight to turn that light on every fastener in the airplane."
Far down at the end of the hangar there is a big sign over the gigantic door where the planes roll out. It says:
ONE MISTAKE COVERED UP CAN COST THE LIVES OF A BRAVE CREW
L. L. Jackson is determined that if he and his inspectors can prevent it, that will never happen.