Accepted: One Fortress

By William W Prescott

Assistant chief, first-production crew, Lockheed Aircraft Corp.

Here's what happens to a Flying Fortress — from the time it rolls off production lines until pilot and test crew take over for the first production flight.

There's a reason for everything — and especially for American plane performance. Working at the tend of a production line which employs thousands of skilled workers, this reason is pretty clear to me. You see, I'm a member of one of the seven crews of eight men each who put the final touches on the B-17s — the Flying Fortresses — as the million-part bombers roll from the line. Until the pilot and co-pilot taxi out onto the runway at Burbank, the plane we have serviced has never been off the ground.

Yet, since Lockheed has been building the Forts, not one has been lost on first production, second production, or acceptance flights. This is the perfect tribute to the efficiency of those thousands, many without prior factory experience, who turn out one of the most complicated mechanisms produced by wartime industry.

A prewar automobile mechanic, I went to work for Lockheed in 1942, scarcely knowing an elevator from a wing tank. My first job was washing the underside of the wings. That's tough, and dirty — the kind of job the new man always gets.

In those days, preparing a Flying Fortress for first production flight required about two days. Today the job is done in about four and one-half hours. The reasons: reduced need for changes and replacements, streamlined operating methods by all seven first production crews, greater familiarity with the airplane, fewer production bugs, increased "know how" of factory personnel, and engineering improvements. These improvements likewise have resulted in a first production flight time cut from approximately three hours to one hour. The Army acceptance flight which follows is also a one-hour hop.

Our eight-man first production crew has G E Summers for chief. There are four engine men, a wing man whose big job is testing the free flow of fuel from tank to tank; two fuselage men, who work over that portion of the plane from nose to stinger, and one swing man, who is a jack-of-all-trades. In addition, we have a radio man, who works all during preparation for flight and makes the initial flight, and an electrician. The latter two are assigned to each plane from their own sections.

The big Fort comes off the production line towed by a tractor. It either goes to the paint shop, where special non-glare paint is applied to certain parts — the all-over camouflage job was eliminated recently — or to the firing range, where the guns are tested, or to the compass rose, where the compass is swung. No matter what the route, the Fort visits all three places, and finally is backed up into the production stall. Then, we go to work.

After all cowling and inspection plates are removed, we fuel up and start line, valve, and flow tests. The electrician and radio man report, and four engine men do the same things. Here's a part of the routine:

Pre-oil, install plugs, and service engine throughout. Check hose clamps, hydraulic lines, propeller governor lines, preset oil pressure and fuel pressures, check carburetor mixtures, check our primers, and check lines through nacelle, wings, and cockpit. Watch for leaks, cracks and dents. Service oil tanks. Adjust turbo. Keep eyes open for anything that doesn't look exactly right.

After these jobs are done — the wing, fuselage, and swing men have been doing their specific chores — everybody starts "working off squawks." On each plane are inspection check sheets. On these the inspector has made a note — a "squawk" — of what's wrong with that particular plane. When a "squawk" is worked off, we report it on the sheet and sign our names. Finally, we prime the oil pumps on our engines, clear away anything in the stall which might be blown over or against the safety screen at the rear of the area.

The engines are now ready for the low power run, requiring not over 35 inches of mercury at 2,350 rpm. The crew chief takes the co-pilot's seat. The mechanic, in the pilot's seat, starts the engines. The crew chief takes readings on all engine instruments. After an initial warm-up of five minutes the electrician mounts the wings, sets the reverse current relays for the generators, and adjusts the voltage regulators.

For the next 25 minutes, the motors are gradually sped up to 2,350 rpm. Oil and fuel pressures are watched, propeller pitches are changed; ailerons, tabs, deicer boots, and everything else come in for their share of attention.

Then comes the shutdown of the four engines. Oil is drained from the sumps and main tanks to be re-refined and used again. We clean all carburetor screens, lukenheimers, oil filters and fuel filters. We reset oil pressures to 80 pounds, if necessary, and fuel pressure to 15.5 pounds. Filter screens must be shown to the inspector. If there is a trace of metal, the cause must be found. Magnets in the sumps are checked. If the cause is found and cannot be remedied the engine is removed. If repairs are made, another inspection is necessary.

After the initial run-up we fill each oil tank with 35 gallons and add 800 gallons of gas to the main tanks. Again we go over the engines to be sure there are clearances between all lines, so that vibration can't cause a failure. Cables and hoses come in for the same attention. In the meantime the inspector has probably written down some new "squawks" to be worked off.

Now comes the final run-up Its length depends on what shows up, but it usually lasts from 30 to 40 minutes. The stall is cleared. The crew chief gets into the pilot's seat this time and runs the engines while the mechanic takes the readings. The engines are warmed at from 1,000 to 1,200 revs for a few minutes; then they are idled back to 650. Some may be turning over faster than that, others may be coughing out. So the mechanics set mixtures and idles on their engines. If oil pressures and fuel pressures vary from 80 pounds and 15.5 pounds respectively, they are again reset. Every one of us is thinking of the men who will fly this ship, and we know those pressures have to register correctly.

Engines are now run up to 2000 rpm. After a time they are dropped to idle again, while the vacuum pumps on engines 3 and 4 are set. The run-up advances to 2,350 rpm. Props are feathered to check the governors. The mechanic gets out of the co-pilot's seat when the engines are again idled and the inspector takes his place. The inspector rechecks all readings, ascertaining that the vacuum is in the 3.75 - 4.25 range. Particular attention is paid the generators. The charging rate must be exactly right, and steady. A "wild" generator will boil over the acid in batteries in less than a minute, and the wings will be filled with a corrosive acid. This is the worst hazard of the ground run-in, and hours must be spent in cleaning up the mess.

Then comes the turbo run-up at full throttle — 2,500 rpm at 45 inches of mercury. Finally, the engines are dropped back to idle. The inspector again sees that they are idling properly. If he is satisfied, he "buys the run-up" Then, after determining that each engine is functioning perfectly, he "buys the engines" and orders the cowling and inspection plates on.

While the crew chief and the inspector leave with all the records and charts to sign out the plane for flight, the crew goes through the plane once more from nose to stinger. Batteries are checked to be sure there was no boil. Controls, fitting, skin, and a hundred other things are examined minutely for any kind of failure or indication of approaching failure. Then all hands fall to cleaning windows and the rest of the Fort.

All of this has been accomplished in four and one-half hours, assuming that nothing radically wrong has materialized. Nine times out of ten, we find that the "squawks" are routine, that corrections and repairs can be made by one or two men in a matter of minutes.

While we are cleaning up the plane, the flight office has been notified and the pilot and co-pilot report. Rightly enough, their trust in us is tempered with caution. They spend between 10 minutes and half an hour going over the plane, inspecting everything that is visible to the eye. Three of our crew are entitled to fly on the first production flight — but only one at a time. The list includes Somers, Melvin Loken and myself, and the man selected is known as the flight mechanic. He is capable of taking care of anything which is remediable in the course of the one-hour flight. In addition, the mechanic who assisted on the low power run-up is taken along. With the radio man, this makes a crew of five.

We all try on our parachutes, make adjustments, and put them in some accessible place, just in case.

Engines are run up for five minutes. During this time, a final, triple-check is made. Then the pilot asks for clearance to taxi out for takeoff. The big Fort lumbers out of the stall, starts to the head of the runway for the first time. The flight engineer takes his place between the pilot's and co-pilot's seats, watching every instrument. This is the big moment. The efforts of thousands of workers and nearly a third of a million dollars have gone into the making of this plane. If anything is wrong, it will probably show during the strain of takeoff. The flight engineer feels the responsibility. He and his gang have declared the plane okay. He knows that the generators, for instance, are one of the biggest problems and that during takeoff and initial climb, when they are overloaded — particularly when the wheels come up — one may go haywire and boil over a battery.

All goes well. A climb is made to 5,000 feet and revs settle to 2,000, with 26 inches of mercury. The wheels are up and the instruments indicate that all four engines are functioning properly. The pilot starts working on his check chart, making notations as he climbs, turns, feathers the propellers, tests the deicer boots, calibrates airspeed, equalizes generators, and does a hundred other things — re-checking all that has been on the ground and making tests on certain components which can only be done in the air. Meanwhile the radio man takes a couple of shots on some station to see that the radio compass is operating properly.

The final test comes when the pilot approaches for a landing, lets down the wheels. Gracefully, the big plane settles, lands smoothly with tail up. Flying speed lost, the tail drops. The first flight is over. If the plane is "ideal" there are no squawks. Whether or no, the first production flight crew is through. Another Fort is ready to be rolled into the stall. As for the job we've just finished, there'll be a final check-over, then the one-hour acceptance flight by the Army.

Since coming to Lockheed, I have made more than 100 first production flights. It might be assumed that, flying in new, untried airplanes, particularly big fellows in which a thousand things could go wrong, that I've had a lot of close calls and thrills.

As a matter of fact I have experienced only two serious mishaps and, strangely enough, they occurred during my first and second flights. On the first, we discovered while landing that the right brake was completely out. With remarkable presence of mind the pilot, seeing that the plane would run off the end of the runway, gave full left brake and right outboard motor. The resultant ground loop was a beautiful thing, with only a scuffed wing to show for it. On the second flight, a wheel collapsed, rolling into a propeller arc which sent it bounding for a hundred yards or so. Since then things have settled down into a production routine marked by nothing more than the usual exigencies of first production flights in such planes.

The main feeling you get out of a job like mine is pride. You get a boot out of the cooperative spirit of our crew, the way it works to a common end — to make the best bombers in the world, sound and solid, and capable of bringing its combat crews back home.

This article was originally published in the December, 1944, issue of Flying magazine, vol 35, no 6, pp 50-52, 142.
The PDF of this article includes photos of a B-17G in flight and of B-17(s) in the final acceptance.
Photos credited to Boeing, Lockheed.