Photo: Challenger 604 Air Driven Generator ("ADG"), also known as a Ram Air Turbine ("RAT").
Have you ever been scared in an airplane? I don't think I have but maybe my memory isn't what it used to be. Truth be known, it never was. But I don't ever remember feeling true fear in an airplane. That's why whenever I hear somebody say they have, it gets my attention. This is a story about a very good pilot telling me about his scariest moment flying a functional check flight. That is no time to be scared. For more about that, see: Normal Procedures & Techniques / Functional Check Flights. The scariest component of his flight was a chief pilot we'll call Jack.
If you would like to see this in French: En français.
"Eddie," I heard as I passed his Highness's office. "You got any flight test experience in that Air Force resume of yours?"
"No, Jack," I said.
"I know that you do," he said. "Now why would you lie to me like that?" It was only seven in the morning and already the day had a bad feel to it. Jack was shaping up to be one of the worst chief pilots I'd ever worked for and the worst thing about him was trying to figure out what he wanted. His office wreaked of cigarette smoke, though he denied smoking. On the walls there were a few pictures of our Challenger 604s along side his official retirement orders from the United States Army. He retired as a lieutenant colonel and began our relationship always calling me colonel. After it became obvious I wasn't about to do the same, I reverted to being Eddie. It's not that I didn't appreciate our common backgrounds as military aviators. It was that Jack had so far shown no signs of integrity and I wondered how he ever got a commission as an officer in the first place.
"I flew functional check flights in Boeings and Gulfstreams," I said. "They were not test flights."
"I don't got time to teach you the finer points of the English language," he said. "We need a test flight on 355 today, it's due an ADG drop this week. I usually do these but I'm too busy. You do it and no more back talk. John's got the details, Carl will be your copilot."
Defeated by virtue of job titles, I left the devil's lair and found Carl sitting in the pilots' office stuffing approach charts into a Jeppesen binder. He was a pure civilian pilot who started his jet aviation career flying for a Hollywood star on his way up and then moved to Compaq as that star's career started to slide. His ever present ear-to-ear grin was missing and he started to speak but stopped.
"Something wrong, Carl?" I asked.
"I just hate these test flights," he said. "I don't see why we have to do them. I'm lucky to be alive after the last time."
"You're talking about the ADG drop?" I asked. "You almost died on an ADG drop?"
"Yeah," he said. "I've never been so scared. We got the ADG deployed okay, as soon as the gear and flaps were up. But we never got the electrical and hydraulic systems back on line until after landing. The brakes didn't work until the last thousand feet of the runway. We're lucky we got her stopped in one piece."
"You did the entire procedure in the traffic pattern?" I asked. "You are kidding me, right?"
"That's how we always do them, Eddie." He slumped in his chair. "It is the most dangerous thing we do around here."
"Carl," I said, "I don't do dangerous. It isn't part of my repertoire. Go preflight the airplane, fuel her to an even ten thousand pounds, and I'll be down in a few minutes."
"Ten grand?" he asked. I nodded. "Yeah, this is sounding better already!"
The air driven generator is simply an AC generator attached to a propeller that is kept inside the nose of the airplane for emergencies where all other electrical power is lost. If that happens, it automatically pops out from its cubby hole, spins up, and starts producing power. I had never seen that but heard it was so noisy you might have a hard time hearing the radio. Every Challenger 604 had to do an ADG drop once a year, just to prove it worked. With almost a year in the airplane I had never done one, but had never heard that it was a big deal either. The only restriction in the flight manual was to keep the speed below 215 knots when testing it. How hard could it be?
I made my way downstairs to the mechanic's lair and found John holding 355's log book while holding court with the two other mechanics. He handed me the book and the test procedure. "Eddie thanks for doing this, please don't break anything."
"What could possibly go wrong?" I said. "Looks pretty straight forward."
"That's not what the boss said last year!" One of the mechanics said, to the other mechanic's delight. John shot them a glance and they both squelched their laughter and left. John pulled me to one side.
"Eddie," he said, "this is between you and me. Every time we do one of these the pilots, I'm not saying which pilots, but the pilots come back with something else broken. Last year they blew all four main gear tires on one jet and had an engine generator catch fire on the other. Every year we do these and the airplane is broken for a few days. You bring this thing back in one piece and I'll buy you a beer."
"Deal," I said. Of course the outcome was never in doubt, but free beer is free beer. I studied the procedure and high-lighted the key steps and added the limitations that were missing.
The airplane was fueled, the APU was running, and Carl was sitting in the right seat with an empty clipboard. I handed him the flight plan and lowered myself into the left seat.
"Eddie," Carl said as he started to program the flight management system, "are we really going all the way over the Gulf and up to 10,000 feet?"
"Sure," I said, "it will take that long just to get set up so why not?"
"Okay," he said. "Jack usually does all this in the local pattern. We never get any higher than 2,000 feet."
"The test procedure says no higher than 10,000 feet so that's where we're going. I like that better than 2,000," I said.
"Me too," he said.
Once everything was programmed and we had our clearance from Houston Intercontinental Tower, I left the cockpit to check the airplane's exterior one more time and returned to the door, where John was waiting.
"See you in ten or fifteen," he said.
"See you in an hour or so," I said.
"One hour?" he said. "The boss is going to blow a gasket!"
"He'll get over it," I said.
Thirty minutes later we were in level flight, at 10,000 feet, and 200 knots. The autopilot kept us exactly where we needed to be and Houston Center gave us the airspace for the next 20 minutes. "Carl let's talk about what we are about to do, what we expect the airplane to do, and about a Plan B if the airplane doesn't perform like the book says it will."
Carl listened attentively and offered a few bail out suggestions I hadn't considered. After we were both satisfied, Carl pulled the ADG manual deploy handle. There was a soft thump and then a large whine. The noise was unbelievable. We checked the electrical synoptics and verified that all the readings checked out. In another five minutes we had all the normal systems running the airplane again and the only evidence of the ADG drop was the whining of the propeller. "Okay," I said, "we can go home now."
Twenty minutes later we were on the ground and Carl was humming to himself. "That was fun, Eddie. I won't mind doing the other airplane with you too."
"Sign me up," I said. We made our ways upstairs, Carl back to the pilots' office and me to the boss's secretary to turn in the flight logs. Jack was waiting, his scowl already in place.
"This better not be what I think it is," he said. He looked at the log and his face turned the next three shades of red. "One point five! Do you know how much it costs to fly that airplane for one point five?"
"No, Jack, I do not. But I am guessing it is less than it costs to replace four tires." He stood, silently, the hue of his face settling on what the Home Depot paint guy would call "burnt amber." His secretary shifted in her seat, diverting her eyes from us both.
"I guess it takes the Air Force an hour an thirty to do what it takes the Army only ten minutes to do," he said.
"I suppose so," I said. "But that's how long it takes me. I'll do the other jet, but it won't be any faster."
Jack retreated to his office without a word. The next day I got the call asking me to do the ADG drop on the second bird. We did it much faster the second time: one point four.