Saturday, August 25, 2012

MERFI 2012, a precautionary landing, and carb ice

Plane: Cessna 150
Route: 40I-I74-40I
Weather: Scattered clouds, 80-90 degrees, wind variable at 5 knots

Unable to attend for the past two years, I marked MERFI 2012 on my calendar many months ago. Somehow time has flown by and it was already three years ago that I last landed in Urbana during the regional EAA fly-in. Gina made the trip with me this year. We took off from Stewart around 9:30 in the morning and were in the pattern at Grimes Field just over 30 minutes later. The place was hopping, the pattern full, and the CTAF clogged, but we sequenced in nicely and I made a safe landing.

2012 or 1942? Just your average summer morning in Waynesville... 

First on the agenda was breakfast. It's not a proper fly-in without pancakes and sausage, now is it? Both of us scarfed down everything on our plates and then wandered around for a while.

The entrance, a nice homage to the infamous Brown Arch

Quite the tasty spread, especially for five bucks!

I went to an FAA Safety Team seminar at 11:00 about runway incursions that counted towards my WINGS credit. Gina wasn't very interested in the merits of proper phraseology on our taxiways so she continued to roam around the airport. After the seminar, which was pretty good, I had the chance to meet up with Samuel. He's another pilot who flies at Stewart who I'd only spoken with electronically up to this point. It's always enjoyable to meet folks who fly there and read the blog!








Gina wandered back over and I said goodbye to Samuel. My bride and I then headed over to the Champaign Aviation Museum for a few minutes to escape the heat and look at their B-25 and B-17. Eventually it was time to head home so we walked back over to the 150 around 1:00.




Here's where the day got interesting...

We took off and I noticed a weird sound shortly after leaving the ground, but beyond the point when I would have landed back on the runway. It quickly became an extremely loud banging noise. At first, I thought it might be an engine problem but all the gauges were in the green and I didn't see anything odd outside. Then I figured it was probably something hanging out the door, but we both checked our seatbelts and headsets and it felt like everything was inside the airplane.

Still, something wasn't right and the noise was really loud. I immediately decided it was best to sort this out on the ground and made a quick lap around the pattern, returning to land on Runway 20. In the end, it was my seatbelt; the very end of it, only an inch or so, had gotten stuck in the door when I pulled it closed. It was so small that I couldn't tell it was caught when I tugged on the belt to check it. But it was certainly big enough to make a heck of a racket banging against the airplane in the wind.

Unedited (other than some added commentary) video of the takeoff and precautionary landing

Problem solved, I started the airplane back up and we again taxied down to the end of the runway for departure. There were about four planes in front of us so we were sitting there at idle for a few minutes before it was our turn. Onto the runway, full power, and...

Well, just watch the video below.

Our second attempt to leave resulted in an aborted takeoff - here's the unedited footage

My best guess, as narrated in the video, is that we were in that magical temperature/humidity range and carburetor ice formed while we were waiting in line for takeoff. I had done a run-up and checked the carb heat; everything performed normally. However, it was a few minutes later that we finally rolled onto the runway for takeoff. Thankfully, it happened within seconds of pushing the throttle in and we were still on the ground.

You may be wondering if I felt we were doomed at this point. Honestly, I wasn't. Although at the time I was thought it was an issue with the carburetor accelerator pump (the carb ice idea didn't cross my mind until discussing it with other pilots later) everything else appeared normal. I did two extended, full-power run-ups and had no issues so I felt confident that everything checked out mechanically. We took off and - finally - headed home on an uneventful, 30-minute flight. Third time's the charm, eh?

More of Stewart's unique normalcy - all these planes were preparing for a stadium flyover

As you can imagine, this was a great learning experience. I feel as though I did the right thing in both instances. Diagnosing a problem on the ground and flying the airplane first (aviate, navigate, communicate!) is always the best option. I'm also a bit surprised that carb ice didn't cross my mind when the engine lost power and ultimately died. Still, I checked everything I could check prior to deciding to fly home and it all checked out. I also know that I'll likely never forget to consider carb ice in the future if I experience anything similar.

And lest I forget, the fly-in was a lot of fun too! :)

Flight Track: Google Earth KMZ File 
Today's Flight: 1.7 hours
Total Time: 235.7 hours

8 comments:

  1. Hmm,.. thoughts.
    1) didn't call you were taking the runway until in position and hold, probably should have announced before crossing the hold short.
    2) When taxing or waiting, did you have the carb heat on? Or was it closed and full rich? Didn't seem to be any stumbling when you did the run up to full throttle and sat there for a second before releasing the brakes. Odd that it reached full throttle without choking or stumbling and then dies rather quickly.
    How did it restart? Smooth without alternate air or stumble?

    I've never experienced carb ice, so just my uneducated questions here. Either way, good turnout and I'm glad it happened then and not shortly after rotation.

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    1. 1) Yeah, normally I call sooner but due to the nearly-constant traffic flow things were operating a tad differently that day.

      2) Nope, carb heat was off and mixture was either slightly leaned or full rich. It's hard to tell in the video, but there was a slight stumble when I went to full power - that's why I held at full power for a couple seconds before releasing the brakes. Restart was smooth, carb heat off. However, I'd been sitting for a minute or so. Perhaps that was enough time in the 90-degree heat for any ice to melt?

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    2. Even in the icing-prone 150, carb heat should be off on taxi - you don't want the engine aspirating unfiltered air that close to the ground. Because of this, I was always taught to check the carb right before take off to ensure that no ice built during taxi. Of course, one of the two times I experienced carb icing in a 150 was at full power on climb-out.

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    3. I was taught about the same and, generally speaking, the run-up is the last thing I'd do before takeoff. We just had some extra time elapsed due to a variety of factors. Lots of traffic and the earlier precautionary landing, both which essentially resulted in more time at idle power on the ground.

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  2. Think the carb ice broke free and clogged the fuel in? choking it of fuel rapidly causing the shutdown?..... Hmm,...

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    1. Seems like a very good hypothesis to me!

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  3. Wow, that was an amazing sound! Story for you: a renter flying one of the 150s at my old flight school in MI had the same thing happen. The renter, certain that the engine was about to explode, put the aircraft in a soft field across the street from the airport, flipped it over, and totaled the airplane - all because of a flapping seat belt. I'm glad your tale ended better than that.

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    1. Crazy! That's why, once I'd scanned all the engine gauges and inspected everything I could outside the plane visually, and all seemed normal I felt that returning to the airport was the best course of action.

      You can probably tell in the video that I turned crosswind sooner than usual; I vaguely remember that being a conscious decision. At the same time, I think it was also fueled by an internal voice guiding me back towards a safe airport landing as quick as possible... just in case it did turn out to be something more serious.

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