Wednesday, May 01, 2013

Bad Vibrations?

Summer pre-dawn departure. I do the preflight inspection in a lighter hangar, then tow the airplane out onto the ramp. The sky is black, with slightly lighter grey patches where a few stratus clouds reflect city lights back towards me. The fuel truck arrives, its headlights sweeping through the dark patches between the well-lit areas of the ramp. They can't exactly put light standards in the middle of an airport ramp. I take a full load of fuel then check the tanks with a flashlight before calling ready to board. No passengers, just crew. We confirm we've completed all the pre-mission items and then go to prestart checks. Master on, nav lights on, cockpit lights on, put the flashlight down. I prime the engine, clear left, turning number one... Start goes smoothly and I record the time on the operational flight plan then start flicking the switches that distribute electrical power to where it needs to be.

Taxiing in the dark is harder than during the day. There are lights along the edges of the taxiway, but spaced out, and it's difficult to see whether a gap between two lights leads onto the next taxiway, or onto the grass. Once I have my taxi clearance I follow the yellow centre line carefully, especially through the corners and at intersections, up to the hold short line. Cleared for take-off I put in the power and watch the runway lights stream towards me until rotation speed when they drop out of sight. Everything drops out of sight. All I can see is the instrument panel and blackness out the front windshield. A night departure is a bit like a departure into IMC. My eyes drop to the gauges and I see the airplane accelerate to blue line, the single engine best rate of climb speed that I must maintain in the event of an engine failure. That's when I raise the gear, tapping the brakes first so I don't put spinning wheels in the wings, then I accelerate to my two engine best rate of climb and turn on course as I was cleared to. As I level off at en route altitude for our eastbound flight, the horizon ahead of me glows in a faint line, illuminated by the not-yet-rising sun. I take pictures, but looking at them later all I see is black. The eye sees what the cheap camera through windscreen cannot.

The second member of the crew is not a pilot. He has no duties on this repositioning flight. When I glance back I see that he has wrapped himself in one of our survival supplies sleeping bags and fallen asleep. I switch the intercom to isolate so the radio calls won't disturb him. When passengers fall asleep I have the same fuzzy trusted feeling as when a kitten sleeps in my lap. In Fate is the Hunter Ernest Gann describes looking back into the cabin during a tense time on the flight deck and seeing a mother nursing a baby. Trust. It makes me proud, but I feel its weight, too.

The sun climbs higher and my coworker wakes up. He hollers, or throws something out the snack bag at me, I don't remember which, to get me to turn the intercom back on. He has seen something outside that disturbs him. There are little sticks, each not much longer than my longest finger attached along the trailing edge of the wings and horizontal stabilizer, part of the design of the aircraft. He has noticed that one of them is vibrating wildly. They are static wicks, designed to safely discharge any static electrical charge that builds up on the aircraft, preventing it from discharging from a more essential part of the airplane and possibly damaging it. The wiggling one did not appear loose on preflight, but everything falls off eventually, I suppose. I reassure him that even if that wick departs the aircraft, it will not affect the flight nor the continued airworthiness of the vessel.

On landing we inspect it. There is no problem at all with either the wick or its attachment point. On this aircraft the static wicks are coated wire, kind of like pipe-cleaners, but not fuzzy. It's a good design because it means they don't poke me in the head when I'm inspecting the control surfaces, and they don't snap off like the plastic ones when someone accidentally brushes against them. They just bend out of the way. and that's what this one has done. It was bent in such a way that air flow over it made it vibrate. We straighten it out and all is good. Maybe it will decrease our drag. This particular crewmember likes things to be straight. I flew with him for months before I realized he was taking time to ensure that propellers were aligned symmetrically after shutdown, before we left the apron after flight. This attention to detail is part of what makes him good at his job.


townmouse said...

ha. I love the detail about the propellers.

Dave W said...

OCD has its plus points!

I do enjoy your posts and must say how nicely this one in particular is written.

On a side note, I'd love to know what kind of equipment you fly (is that the correct term) but I'm guessing its a detail you'd rather not share?

All the best

Dave from the UK

majroj said...

Had a car antenna like that, fine until it hit about 65 mph airspeed, then it oscillated in an oblong about 6 inches at the top/end.

I know what you men about those blue taxiway border lights. I almost drove a rescue truck between a pair into a ten foot deep ditch during a 2 AM code-3 response. (Didn't help that I was actually seeing double, having been shocked awake by the station bell tight over my bunk).

RTD8450 said...

WOW! Fine writing, capturing the intense concentration, but also the wondrous experience of flight! Cheers to you, the PIC and (some) kudos to your "crew" for being on the ball.

Frank Van Haste said...

Dear Trix:

Some FBO's train their ramp crew to align the prop(s) after fueling the aircraft. Allows others a visual check that "yeah, they got to that one"; if you land at such a place, your co-worker will inadvertently skew the system.