Monday: RPMs and magnetos

Do you have any idea how tricky it is to find 29 Palms Airport from the air (even with help from that little purple line on the GPS)? Jeez, they hid that sucker. We were only five miles away from the place when we spotted it, but we did find it, and landed on it. And thus, after three days of cancellations and postponements, Harold and I finally managed to make it to 29 Palms. This marked the second dual cross-country we've done together, and the longest: nearly 100 miles round-trip. I now have barely seven hours of requisite flight-training left, and then I'm through with my private pilot's license. I wanted to spend all four days of Thanksgiving weekend with the fam-bam, so I scheduled my three weekly flying lessons on Monday, Tuesday and Wednesday of Thanksgiving week. Yep, I'd be flying three days in a row: quite a cram session. That didn't bother me. There was some exciting stuff in the offing. On Monday I'd be soloing, but I'd have the reins to myself: nobody would be in the office, even. The book with the key and the required documentation would be left in the plane for me, and I'd simply walk straight through the airport building, climb inside N42126, and go. How cool is that? Tuesday and Wednesday would be given over to cross-country. On Tuesday, Harold and I planned to fly to 29 Palms, a town of some size and scenery west of here (near an also-sizable Marine base). On Wednesday, I'd solo to 29 Palms and back. It didn't fall out like that, though. Heck, no. Let's start with Monday. I got to the airport, duly bypassed the flight school office, and sauntered right out to the plane. I leisurely performed my preflight inspection, a self-satisfied grin on my face as I planned the takeoffs and landings I'd practice and the maneuvers I'd pull over Bear Valley Road. I climbed in and started the plane, not without some difficulty. It's been getting down below freezing at night lately and when it's cold, the engine gets cranky (no pun intended). So I primed the bejesus out of it and finally fired 'er up. Everything was proceeding normally until I taxied down to the run-up area for runway one-eight. As soon as I tried to throttle the oldLycoming engine up to 1700 RPM for my run-up, something weird happened. Dumbo swooped down out of the sky, opened the door of the plane, and handed me a complimentary in-flight bag of peanuts. No, no, I'm just kidding. That would've been really cool, though. What actually happened was this: the RPMs started fluctuating rather severely. Instead of smoothly accelerating up to 1700 (from 1000) the tachometer needle jumped and jerked and stopped and started. The engine's smooth roar suddenly tripped and staggered. I powered down quickly, then cautiously powered up again. The same thing happened. The third time, the power succeeded in reaching 1700 RPM, but it wouldn't stay there. The needle wobbled back and forth, as did the pitch of the engine noise. Not good. Well, I didn't want to muck with it if there was something screwy preventing the pistons from revving smoothly. I didn't want to be caught in mid-air with my pants down. Not in an airplane, anyway. So I taxied back to the ramp and, lo and behold, there was Harold. He'd just dropped in to the airport for a few minutes with his eldest son before driving all the way down to Oceanside to pick up (heh heh, didn't I think this was appropriate under the circumstances) a new engine for N42126. "You just heading out?" Harold asked as I got out of the plane. "No, just coming back, actually," I answered as I unfolded myself. I proceeded to explain the trouble. Harold, puzzled, got in and (with me standing over the right seat, with the door open), proceeded to fire up the engine. Before I tell you how that went, let me share a few choice words about what it's like to be standing anywhere near a propeller aircraft when it's going full blast. You know how when you're riding in a car you're completely oblivious to the amount of air that's moving past just inches away from you? That invisible element, howling along at ridiculous speeds, casually and undetectably deflected by the windshield? Well, now picture yourself standing under the wing of a Cessna 172, only your head and shoulders inside, the door open, directly behind the propeller whirring at full speed, the engine roaring, the wind screaming past you. I felt like I was going to get caught with my pants down after all, because the wind was about to tear 'em off. There was absolutely nothing wrong that Harold could detect. It seems that in between the run-up area and the ramp the mysterious engine ailment had melted away. Perhaps literally: Harold figured Imight've had a little ice in the carburetor. The run-up had probably melted it (or me turning on the carb heat halfway down the taxiway and therefore negating the reason for returning to the ramp in the first place). Harold believed me, and I know he didn't hold it against me or think me silly or overcautious. He's a good man and a good instructor. Plus he knows that, in the world of flying machines, there's really no such thing as overcautious. (My old flight instructor Mike used to tell me, "There are old pilots, and there are bold pilots, but there are no old, bold pilots.") But I felt pretty stupid regardless. Anybody's bound to feel frustrated when they perceive a problem (say, a hideous monster lurking just outside the window) and then when everybody turns to look, the problem has vanished. Makes you doubt yourself. Anyway, not to be thwarted by some minor technical difficulties, I jumped back in the plane and taxied back to the run-up area for the second attempt. No soap. This time it wasn't the RPMs, it was the right magneto. During run-ups, it's customary to check the magnetos and make sure they're both working properly by turning them off one at a time and seeing if the other still runs. You do this by flipping the key in the ignition switch to "L" (leaving the left magneto on, and turning the right off), then back to "BOTH"; then flipping it to "R" (leaving the right on, and turning the left off) and back to "BOTH." As you do this, you observe the tachometer and make sure that the RPMs don't drop by more than, say, 250 (when one of the magnetos is off). Well, darn. That morning, whenever I turned the key to "L," the tachometer needle would fall like an egg from a tall chicken. I had to flip that switch back to "BOTH" but quick; the RPMs were falling off so fast I was afraid the engine would just die right there. I repeated the test three more times, with the same result each time. The hell with it, I finally decided. Flying like this wouldn't be advisable, or safe, or sane. Normally I'm the first guy to try something inadvisable, unsafe, or nuckin' futs, but I didn't feel like it this morning. Particularly not in a rented airplane. So I taxied back to the ramp (Harold had departed in the meantime), shut down, secured the plane, and stomped back to my car. I left a note in the cockpit explaining the trouble, and drove back home. That was Monday's flight lesson.