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Best of Airways — Engine Out Ferries

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Best of Airways — Engine Out Ferries

Karl Gritschke

Best of Airways — Engine Out Ferries
August 04
14:00 2017

By Captain John Marshall • Airways Magazine, May 2017

In the early days of jet transports, the engine that powered the Boeing 707 and Douglas DC-8 was the familiar Pratt & Whitney JT-3. It was huge by the standards of the time, but not so large that it could not fit into the cargo deck of a 707 or DC-8 freighter.

Only an exceptional circumstance would require a three-engine ferry of one of these early birds, because it was every bit as practical, not to mention considerably safer, to carry an engine to a wounded plane.

The JT-9 family of gargantuan behemoths that powered the huge new Boeing 747, however, was another story. Along with its cousins, the Rolls-Royce RB-211 series and the General Electric CF-6, these beasts were too large to fit snugly into the cargo deck of the older freighters—and took up so much weight (which equaled revenue payload) in a 747 cargo ship—that airlines began to search for alternatives.

One solution, applied to the 747 by several airlines, was an ingenious innovation known as the ‘fifth pod’ (Airways, May 2016).

Boeing and its engineers, at the behest of the airlines, began researching the feasibility of actually carrying another engine slung under the wing to ferry it to wherever it was needed. The engine was carefully prepared and enclosed in a fiberglass cocoon, which was then fitted to an attaching point under the wing between the number two engine and the fuselage. Snugly housed, it got a free ride to wherever it was needed.

More than one passenger did a double-take after a casual glance at his chariot revealed an extra engine!

But there were several disadvantages to this system. The sacrifice in allowable weight (payload) and the penalties in altitude and speed were considerable. And, of course, there had to be a 747 going in the right direction anyway to make it worthwhile. The fifth-podding of an engine as the sole reason to dispatch an airplane would seldom make economic sense.

The alternative solution was almost an afterthought. The airplane was certificated to fly on three engines at virtually all gross weights and under every conceivable condition.

Why, then, if the conditions were right, couldn’t an aircraft take off on three in the first place—and transport the ill fourth in situ to where it could be repaired? It was an ideal solution, and the airlines soon adopted the practice.

I have been involved in several engine-out ferries, on both the Lockheed L-1011 and the Boeing 747, and they were all memorable.

At Pan American (PA), these trips were always flown by Supervisory Pilots, after much diligence and consideration of the circumstances. They were undertaken usually as a last resort when the logistics so dictated.

The procedure was not taken lightly. The Pilots were required to practice the maneuver annually in the simulator, under very strict protocols. All unnecessary galley and cabin equipment was removed. The airplane was drained of water and no supernumeraries were permitted; only the bare essential operating crew was permitted aboard.

The maintenance manual dictated an intricate and lengthy procedure to make an engine ready to be carried inert. A flat plate insert was affixed to the front of the engine to prevent it from rotating, and many of the accessories were removed. The finished product looked very much like a plucked chicken.

The performance-engineering wizards produced special charts and tables to reflect the reduction in takeoff performance, and the flight operations department developed the procedures and techniques needed to make it all work. The finished product was a procedure that was as safe as it could be.

I was involved in a couple of three-engine ferries of Boeing 747s that were just a bit outside the norm. The airplane in question was an ancient 747-200B of a colorful lineage that had been resurrected from an Old Airplane Home in the desert and flown to Southeast Asia, where it would serve one last glorious enlistment to fly a Hajj—carrying pilgrims to Mecca. Reluctant from the start, it eventually contracted a near-fatal affliction in its number three engine.

After worrying us for several days, the engine failed to start during pushback for a routine scheduled flight. Its disease was eventually diagnosed as a split in a fuel line that was nestled deep in the innards of the engine itself. The cure would require the virtual dismantling of the engine. It was a task far beyond the capabilities of the personnel and the facilities at hand.

It fell to me, one of the chief Pilots of the operation, to undertake a three-engine ferry from Jakarta’s Halim Airport (HLP) to the huge maintenance facility in Singapore for repairs (the fact that I was the only Captain at hand who had ever flown an engine-out ferry in a 747 no doubt had a bearing on the selection process).

The vintage buildings and the rural, laid-back atmosphere of the regional Indonesian field seemed to shrink it, to make it smaller than it actually was, and our huge airplane dwarfed it even more.

It was bucolic, with native villages pressed tightly to the boundary fences of the airport itself. It seemed more suited to Charles Lindbergh and Amelia Earhart than to a preposterous 747.

The taxiways were narrow and constricted, the turns sharp and unforgiving. It was plainly evident that the airport had been born long before the concept of the jumbo jet. The runway was long enough—just—to accommodate a full airplane on four healthy engines, permitting liftoff in its confines with enough fuel to fly its mission.

An engine-out ferry was another story. We had access to operating manuals not only from the manufacturer Boeing, but from two different airlines. We pored over charts and tables to determine whether we were indeed mad, or merely foolish.

The airplane would be stripped, right to its bare essentials, so that the term Basic Operating Weight would actually mean something. The 747 would carry only essential crew and enough fuel to fly the two hours to Singapore with bare minimum reserve. The weather was seldom a problem in the region.

The three healthy engines started and we taxied carefully to the very end of the only runway. The charts reassuringly showed that we would lift off with many meters to spare; once aloft, second-segment problems didn’t concern me.

The rural areas surrounding Jakarta, and in the vicinity of Halim Airport, in particular, were thankfully flat. Of course, our plans were predicated on everything operating perfectly, with no hiccups from any of the remaining systems.

The actual takeoff procedure was deceptively simple. The bad engine was an inboard one, obviously the most favorable scenario. We would turn onto the runway, using every available inch of concrete, and, once turned down its length, set the brakes.

The two outboards would be set at maximum takeoff thrust, and the lone inboard, number two, set at 70% RPM (we used N1, the primary compressor stage; it would produce roughly 70% of maximum thrust). The brakes would be released and, as speed gradually increased, number two engine would be carefully brought up to max power. The trick was to bring the thrust to bear at the same rate at which the rudder would provide enough authority to keep the aircraft on the straight and level.

It was a heart-in-the-mouth exercise, fueled by the thundering heartbeat of the healthy three engines, and the prayer that they remain so.

As I released the brakes, I said a silent prayer to the gods of Pratt & Whitney and eased up the throttle (which is now called a ‘power lever’) on the number two. The rudder was against the right stop, to match the asymmetrical thrust, and, after agonizing seconds that seemed like long minutes, I was able to ease the rudder and wait for Vee One. The multitude of villagers that attended every takeoff raced by, a blur in my peripheral vision.

Finally, we flew, and the rest of the flight was an anticlimax, remarkable only for the fact that we were flying so slowly and at such a low altitude.

Singapore was soon in the windscreen and, after a routine landing, we were directed to one of the massive hangars that made up the maintenance base. By the time we had deplaned, the cowling was off our reluctant engine, and the wrenches were hammering at the innards of the big Pratt.

The second verse to that same song was played out about a month later, and this time fate again placed me at the controls. It was the same airplane, but the opposite inboard this time. It had ceased to share its burden of the load about halfway from Jakarta to Abu Dhabi (AUH), and we nursed our sick companion gingerly across the Arabian Sea to a landing on the wonderfully long strip at our destination.

After a day of frantic phone calls back and forth across the Atlantic, an engine was located in Chicago; it would be airlifted to Paris-Orly (ORY) where the Air France maintenance facility would effect the change.

All we had to do was get our sick friend to Orly. We ran the numbers: the flight would take nearly eight hours, at an impossible altitude and speed. It would feel like flying a twin Cessna to Paris. A major obstacle was the lack of charts and approach plates. We covered the Middle East and Southeast Asia pretty well, but Europe and the Mediterranean were large blanks in our route manuals.

I spent a long morning at the Garuda Operations office, laboriously copying reams of plates from every airport along the way that could conceivably be considered an alternate.

While our erstwhile sick friend, the number three engine, had behaved pretty well, we still didn’t trust it completely. It would cough or hiccup at inopportune moments; just enough to give us pause. In the back of my mind, I felt as though we were going to Paris on two and a half engines, and I wanted plates for every contingency.

The final obstacle was Orly itself. While Garuda did serve Paris, it did so through Charles-de-Gaulle Airport (CDG), the huge new facility at Roissy.

Orly charts were nowhere to be found in the Garuda Ops office. Ditto British Airways and Lufthansa. Air France was our last hope; surely they would have Orly charts? Of course, they did, with the legends and notes entirely in French!

No matter; the essential numbers were there, and I had been to Orly enough times myself that, with a good forecast—which we fortunately had—we decided we would wing it.

We left at dawn. The impossibly long runway stretched out ahead, giving us the luxury of easing in the power and the leisure to carefully assess the health of our three operating engines before committing.

The climb to 23,000ft took what seemed like hours and, once settled in at cruise, we had plenty of time to enjoy the scenery as it slowly rolled by beneath. I made careful note of the usable airports as they passed by, keeping each in the back of my mind.

The weather was picture-book, and even the French Controllers in the Paris area seemed more laid-back than usual.

In the gloaming of a late June afternoon, we settled onto the runway at Orly and even managed to find our way to the maintenance hangar with our Air France road map.

It had been a long day, but a successful one.

Captain John Marshall accumulated over 30,000 hours while flying for Pan American World Airways and Korean Air. He is currently retired from airline flying and is an Air Carrier Operations Inspector with the FAA. In his spare time, he flies a World War II B-25 bomber with the Commemorative Air Force.


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John Marshall

John Marshall

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