Production flying consisted of four hour flights each. Everything on the aircraft had to be tested to make sure it worked. There was a checklist type book that we recorded every test results. This ‘book’ was about 8 inches thick with hundreds of items to be tested.
On average, about 4 to 5 prod flights, as they were called, were needed to complete all of the tests. When things didn’t work and maintenance had to make repairs/fixes/adjustments, etc., that usually meant one more production flight. So sometimes a plane made 6 prod flights.
Some tests had to be made at night so production flying always meant you would fly at least one of the prod flights at night.
Although I worked in training and enjoyed it very much, I loved production flying the most. But most of my hours were spent as an instructor and a lesser amount of my flying time was done flying as a production FE.
Like all of the jetliner manufacturers, you were used where needed and as needed. So this meant that when we needed more ‘instructors’ we would borrow from the production crew pool. When production flying was hot and heavy they would borrow from the training pool.
To give you an idea of what was tested, here I’m listing just a few, but remember there were hundreds and hundreds of tests made.
(1) First Flight. On the very first flight of the aircraft, on the runway ready for take off, one of the wing engines was run up to full take off power while the pilot put on the brakes. This was to make sure one of the engines could achieve full take off power and was in fact the first time the engine was run at that high of a power setting. Once full take off power was stabilized, the other two engines were powered up while at the same time releasing the brakes and we were on our way down the runway! Surprisingly, the TriStar, when empty, really pushed you into your seat back on take off.
(2) Wet Compass Calibration. Flying on the autopilot, the pilot would dial the heading knob to 000 degrees and then check the wet compass. Once it settled down, using a plastic screw driver, he would turn a bias screw in the wet compass and adjust it to 0 degrees.
(3) Fuel Dump. To verify that the fuel dump system really works, fuel is actually dumped on the production flights. Two things surprised me about dumping fuel from the TriStar:
- When the FE in the cockpit opened the fuel dump valves, the amount of fuel exiting the aircraft was massive. This surprised me, the amount of fuel that could be pumped out of the tanks just aft of the trailing edge of the wings. It was like a fire hydrant, just a huge amount of fuel going out.
- When the FE closed the fuel dump valves, I was surprised to see the fuel continue to leave the aircraft for such a long time. About 10 to 15 seconds before it finally started to stop flowing. At first, initially, I thought the fuel dump valves failed to close, but they did close.
(4) Front Landing Gear Doors. The front nose gear retracts/extends forward into the wheel well and then two doors close after it. The key here is knowing that these doors are just mechanically linked to the nose gear strut.This is important to be aware of. The test that we had to make was to make sure the landing gear could be extended and specifically that the nose gear would lock down at a speed of at least 230 knots indicated. Above that speed, the nose gear might not lock down. Why? Because the air flow would hit the nose gear strut and be deflected upward into the wheel well and then, in a kind of loop, exit the wheel well downward.
Because the nose gear doors are linked to the strut and try to close when the gear is extended, the nose gear being down creates the upward flow of air into the wheel well and then the down ward flow puts pressure on those two doors trying to close. The result is that the hydraulic system should be strong enough to force the strut down and (being linked to the doors) force those gear doors closed.
Our test would be to fly on autopilot and auto-throttle at about 240 knots indicated and then put the gear down. We’d expect the nose gear to not lock down due the air flow pushing the doors down ward. Then the pilot would reduce the auto-throttle setting one knot at a time and wait for the green down and lock nose gear light. If the rigging was right, when 230 kias was dialed in, we’d see the green light illuminate. If not, it was a write up for maintenance to re-rig the door cables.
(5) Alternate Landing Gear Extension. The TriStar had two alternate landing gear extension systems. Both were tested on the production flights. The first was simply a manual gear drop. Three handles were on the floor, behind the center console. The FE would open the cover and pull up about 16 to 18 inches on each handle and the handles would lock into place. Each gear was done one at a time before the next gear was dropped. Each gear would just fall and locked into place by gravity.
The other alternate method was to discharge a small nitrogen filled bottle (gas pressure) into the hydraulic lines and try to ‘blow’ or force the gear down and locked. This was a red guarded switch under the same floor cover that the FE would flip to the extend position.