Sunday, May 09, 2010

A mother of a day

I wanted to go flying today, but there were certain obstacles. One might think from the title of this posting that today being Mothers Day might be one of them, but unfortunately that's not the way I meant it. I left off the second half of "mother" so as to preserve this blog's PG-13 rating.

Obstacle number one was the fact that there was no oil in the airplane, that crucial fluid having been drained out on Thursday in preparation for a full seven quart replacement thereof. As long as the cowls were to be off, I also wanted to see if 1) there was anything I could do about the oil pressure reading I've been seeing on the eponymous indicator on the control panel, and 2) find a better way of securing one of the hinge pins that provides the thankless yet important function of holding the top cowl to the bottom cowl.

Replacing the oil was easy. Nothing else was.

Safety wiring the oil filter has been very difficult ever since I removed the vacuum pump, improvements in the ease of maintenance as a result of a change in another area being known as what's called a "zero sum game." You can click on the Wikipedia link that I provided, or just use my definition: win-lose. While it's easier to get the filter on and off with the increased accessibility, there is no longer a convenient object to safety wire it to. There's a little tab (a very little and, as it turns out, brittle tab) formed into the engine case for this purpose, but I have yet to own an engine that didn't have that tab broken off. It now takes much longer to get a good wiring job in place because there just aren't all that many suitable places to wire it to.

Once that was (finally!) done, I adjusted the oil pressure relief valve in hopes of correcting my high oil pressure problem. What's been happening is the oil pressure is indicating at 90 psi and occasionally above, which is right up against the allowable limit as determined by Lycoming. It's their engine, and I figure they ought to know what's best for it, oil pressure apparently being one of those good things that it is possible to have too much of. You know, like vodka. I talked to my mechanic about it and he suggested a quarter turn adjustment. I also consulted Google - my go-to second opinion:

Pressure relief out of adjustment: If the pressure relief valve is not operating properly, the oil pressure follows the throttle because the oil pump is engine driven and speed sensitive. Lycoming limits are 60 to 90 pounds, with a range of normal 25 when idle go to 100 psi during starting and run-up. See oil pressure specifications in the applicable operators manual before making adjustment.

Lycoming engines: External adjustable type (part number 77808) increase oil pressure by turning adjusting screw clockwise, and to decrease turn counter-clockwise.

I've long suspected that the relief valve was sticking, but it was worth trying the simple adjustment first.

To fix the cowl hinge, I simply made a new one out of some hinge pin material I kept from the rivet repair on the top cowl. It just needed to be a third of an inch longer. That was actually as easy as replacing the oil, so I was actually being a bit too dour when I stated that pouring seven quarts of oil down a tube was the only thing that was easy all day.

I test ran the engine and monitored the oil pressure - it worked great! At 2,200 RPM (an uncomfortable level of power to hold in restraint with the brakes), the oil pressure was reading between 70 and 80 psi. Perfect! As expected, there were also no indications of oil leakage. It's pretty good about staying in there once I get it in there.

All that was left to do was put the cowls back on. Unfortunately, that is my most hated job in the entire encyclopedia of Jobs I Can Do. It's listed under 'A' for Aww, Crap, I Gotta Do That Again?? I usually enlist the aid of a helper for replacing the bottom cowl as it requires someone to lift it into position while the other slides the hinge pins in during the rare and brief periods when everything is in alignment. Doing it alone requires the patience of Job and the dexterity of a circus gymnast. I possess neither.

It took forty-five minutes, and half an hour of that was trying to get the left side bottom pin to go in. That pin has to fit between the very small gap between the exhaust pipe and the bottom of the fuselage, and requires three hands to be able to work in an opening insufficient for only one. That part of the cowl is getting pretty beat up as well and requires some professional work. Since I will probably be trying to sell this airplane right around this time next year, I'm thinking of trying to find someone with more experience with this facet of the plane than I have that I can hire to fix it up for me. I eventually got it done, to which I credit the lubrication of exotic curses applied quite liberally.

The top cowl can either go on easily or fight like a Marlin.

Today was a Marlin day.

One of the things that can go wrong is for me to forget to put a couple of pieces of loose safety wire through the first hinge loops of the hinge strips that run along the back top seam of the cowl and the front of the firewall. I need those wires to twist around the end of the hinge pins to keep them from backing out in flight when the vibration of the engine shakes them loose. Many is the time I have fought the cowl into place, only to reach in for those wires and find that I have forgotten to put them in place. What I do now is put them in as soon as I remove the cowl so I won't forget.

The last wire to go in is the hardest to get at. It is the one that goes from the center of the cowl and down to the right side of the fuselage. I have to reach in through the oil door to get it in, but that means I can't see what I'm doing because the oil door is too small to accept both an arm and a pair of inquisitive eyes concurrently. In this case, the eyes don't have it. I have to feel around with one finger trying to get the pin started in the first hoop while trying to hold the pin with the rest of my fingers. If I drop the pin, the cowl comes back off to retrieve it.

I got the pin started and the first six to eight inches went in okay, but then I hit a wall of resistance. That usually means that the front of the pin has reached the part of the cowl where it starts to curve down towards the side of the plane. When there's resistance, it usually means that I have to use my free hand to wiggle the cowl a little bit to line up the hoops while pushing harder on the pin with my captive right hand. That worked for about an inch and then stopped cold. No amount of pushing and wiggling would budge it. I pulled out my arm and grabbed a flashlight to peer through the oil door to see what the problem was.

The pin had not been started in the hinge hoop after all. It had actually worked its way between the hinge hoops and the edge of the cowl. That worked fine (as far as pushing the pin in - it hadn't done one iota of good as far as holding the cowl onto the airplane) right up until it got to the curved part. Unfortunately, it was well and truly jammed in place. I couldn't pull it back out. After a prolonged struggle, I finally got it loose. I looked back through the oil door before trying to put it in again. I didn't like what I saw.

The safety wire had come out with it.

If a first date had gone like this, not only would I never have called her again, but I would also have burned the dinner receipt, shredded the credit card that I used to pay for the dinner, thrown the cell phone that I called her with into a septic tank, torn her page from the phone book, and dedicated my life to building a time machine so I could go back to the day before I met her and become a Tibetan monk.

Next obstacle: mowing the lawn. Have I ever mentioned how much I hate string trimmers, aka Weed Whackers, and how awful those little self-extending string hub thingys are?

I'll say no more about that.

Finally, though: ready to fly. The latest DUATS observation had the winds at 7 knots, and at that speed, who cares where they were coming from.

When I checked in the with tower for taxi clearance less than half an hour later, the winds were 14 gusting 19, directly across the runway.

Someone, somewhere, has the observational skills of Mr. Magoo.

My personal limit is 15 gusting anything. Anything equal to or greater than that keeps me on the ground. I could have either said "too close to my minimum" and
shut down the plane, or decided that the whole point of having a minimum is to have a solid line drawn in the sand that I will walk up to but not cross.

I flew.

The first thing I noticed at the end of the runway was that the oil pressure was reading right up against the red again. It had been fine during my test run and while taxiing out, but was reading too high again. It was within the allowable limits, of course, but it was being inconsistent and that's something I can do without. I am back to suspecting that the valve is a little bit sticky. Being as it was still within limits, I went ahead and took off.

Wow, was that a ride! With a 14 knot wind from the left, I knew I'd have to hold a little left aileron and a LOT of right rudder to track straight down the runway with both the torque of the engine and the wind pushing on the vertical stabilizer trying to turn me to the left. The wind wasn't at all constant, though, and was in fact pounding at me like a howitzer:


Each pummel changed the pressure needed on the rudder. My feet were doing a St. Vitus' dance trying to keep the runway more or less centered in front of me. The left aileron that I had pre-fed into the wing was too much - once we picked up a little speed, the right wing lifted more than I had expected it to. When I released the aileron, the wing dropped back down hard enough to bounce the right wheel back up into the air, and the wing went right back up with it. The rudder was still moving like a hyperactive eel and the wind was still firing cannon bursts into the whole operation. I jabbed some right aileron in to get everything settled down, but that only served to bounce us up into the air about 5 mph too soon. Naturally, with the cool temperatures and the high atmospheric pressure, the engine was doing a fabulous job of making all of this happen quite quickly. With a lurch, we were in the air. Not that the contortions lessened once we broke the cloying bonds, mind you - it's just that the ground was no longer involved. That's always a relief. Air can be brutal, but it's seldom solid.

I went eight miles to the west, decided the flying wasn't going to be any fun with the Domaclesian blade of the impending landing hanging over me, and turned back.

This put the wind at my back and we fairly scooted back to the airport. Figures, doesn't it? I was sure in no hurry to get there, but man were we flying!

I reminded myself that I'd have to make my turn onto final much earlier than normal since the wind would be pushing me towards the extended centerline of the runway at a prodigious clip, and it's good that I did. This is where bad (and nearly always fatal) wrecks come from; a pilot starts his turn onto final, the wind keeps pushing him further away from the centerline until he overshoots, he steepens the turn to try to get back, the view out the window is totally screwy, and he ends up in the classic stall and spin into the ground. The right thing to do is start the turn early and just let the wind blow you onto the correct approach path. Worked like a champ.

With the wind as strong as it was, I elected to make a no-flaps landing. That lets me keep my speed up to penetrate the gusty wind a little better. It also has another salutary aspect which became apparent once I got to the runway. Before that, though, I had to fight my way down the final approach. When it's gusty, I hold a little extra airspeed in case I need it. Today I did. The gusts were hard enough to periodically knock a 15 to 20 degree bank into the wing, and the extra speed of the air across the wings gave me more aileron authority to correct it. I was also using quite a bit of rudder to counteract the left bank that I was using to keep from being blown off to the side of the runway and that too was made more effective with the increased air speed. Finally, when I inevitably hit a sink hole, I had enough energy left to correct with a little back stick and a small burst of power.

The landing itself was ugly. Without the flaps and with the extra speed, the runway approached FAST. I misjudged the flare at right around the same time I got hit with a gust, the combination of which gave me a pretty healthy bounce. The second bounce was smaller, and without the flaps to give the wing increased lift, the third bounce was enough to sap enough energy out of the wing for it to give up any further thoughts of flying. I was ready to quit after the first bounce. I was glad the wing finally saw it my way.

All in all, the landing was about as good as can be expected. It was safe and fully under control, but definitely not one for the Hall of Fame as far as aesthetics go.

It was outstandingly good practice, too, and confirmed that I have my personal minimums set appropriately.

That said, it was also the first time I can remember hearing my heart thumping even as I was bringing the hangar door down.


  1. Perhaps it's good you didn't elect to head out this way! After 12 hours outside, we still have about 40% of the dirt on the driveway. Home projects never come in ahead of schedule and under budget...

  2. I was thinking that too. A bit windy for an unfamiliar and smaller runway. It was more a matter of being a hectic, busy landing than anything dangerous, but it helped to know I had a mile of wide runway to aim at, and if I bent the airplane I wouldn't need a ride home.

  3. "I left off the second half of "mother" so as to preserve this blog's PG-13 rating."