Dodging a Bullet
A few weeks after we got the airplane out of annual, Connie and I took off on a cross-country flight to Branson, MO. We were going to meet her family there to celebrate her mother’s eightieth birthday. As always, the flight started by sneaking out of Houston under the Class B, level at fifteen hundred feet as we pressed east. As we passed the fifteen nautical mile circle from Hobby, I climbed us up to twenty five hundred feet and then squeeked us up a couple of hundred feet more to avoid the possibility of hitting anyone flying west at their even plus five altitude. I had to wait a bit before I could climb up any higher; we were staying under the Class B shelves a little longer than we normally did to angle more northeast and stay over dry land.
As we left Baytown and then the Taylor County airport behind us, we exited out from under the Class B rings and became clear to climb. Our course would take us just slightly east of north, so our correct cruise altitude was “odd plus five”. I planned to climb us up to three thousand five hundred for now. I shoved the throttle forward, and then engine responded, but roughly! Connie wasn’t saying anything, but I knew something wasn’t right. The outside air temperature had been in the seventies on the ground, so the first thing that popped into my mind was the possibility of carburetor icing. I pulled the carb heat full out and the engine seemed to smooth out a bit, so I left it for a minute or so and out it back in. The engine got rough again, so I applied carb heat again, and it smoothed out; when I reduced carb heat and the engine got rough again, I realized that carburetor icing was not the problem. My airplane’s engine has always run rich, so I started leaning the mixture back to see what would happen. Engine operation smoothed right out, so I continued the climb, checking my engine’s parameters, which all appeared normal. We leveled off at thirty-five hundred a few minutes later and everything seemed fine, so I climbed us up to fifty-five hundred where we leveled off for the rest of the flight.
We hit Branson the same weekend that a bunch of other Grumman owners were flying in. While we didn’t run in to them during our Saturday and Saturday night there, we did happen to be out at the airport and parked just off the departure end of the runway, when most of them were departing. I’ve long suspected that, while Cheetahs are not know for their stellar climb performance, ours was worse that the average Cheetah. While it was often impossible to tell whether any particular four-seat Grumman was a Traveler, Cheetah, or Tiger, some of them were marked with the model name. All in all, they were all airborne by the time they hit a third of the runway length. When we took off, we didn’t lift off until we had eaten up just under half the runway length. There were moments when I wondered if we were going to get off…
Returning home, at fifty-five hundred feet I could only get two-hundred feet per minute climb.
A few days after I got back, using the pilot’s operating handbook, the actual performance I had observed, and one of my old college airplane performance textbooks, I calculated we were 18 horsepower short of where we were supposed to be. I had assumed standard day conditions which, of course, we didn’t have; so the actual number was probably less than that. Still, it was confirming my feelings that something just wasn’t right. Our fuel consumption rate seemed to confirm that; it normally was 8.5 gallons per hour and on this flight it had been 10!
I called my mechanic and discussed what was going on. We had not really looked into the carburetor, and that made sense as a good place to start. So, he dug into it and found the throttle plate bushings were extremely worn (causing some internal leakage within the carburetor) and the accelerator pump had a hole in it, reducing overall gas flow to a trickle of its expected self.
Despite my mechanic’s prediction the airplane would accelerate much faster, I couldn’t sense any added speed down the runway when I lifted off. I climbed the bird up to thirty-five hundred feet and forty-five hundred feet on a couple of occasions, and climb performance didn’t seem to improve but did seem to hang in longer before falling off. At about five thousand feet, I was seeing about four hundred feet per minute. But I also noticed a pronounced engine roughness at full throttle, even as low as fifteen hundred feet. I took the airplane back with that complaint about two weeks later.
Bill thought the carburetor might be dumping too much gas in at full throttle, so he checked it. It seemed to be set correctly, so he did a run-up and noticed that the engine ran rough when running on the L mag, even though the mag drops where within limits. He checked the associated plugs and found one on the number 2 cylinder was oil-fouled. He cleaned it up and tried it again, and it oil-fouled almost immediately. Feeling that the problem might be in the magnetos, he took them apart and found that the left mag was about to fail due to some cracked parts. He also borescoped the number 2 cylinder and determined there was blow-by past the rings and on the intake valve side, but thought the cylinder had some more life in it before being overhauled. (He estimated 200-300 hours. We had only one cylinder that showed anything a bit off in compressions, and I didn’t think it was the #2.) He called and told me the mags were about to fail and would have had I flown it much longer before calling him in. We had dodged an “engine-failure bullet”, though the failure might have produced only a precautionary landing rather than a full off-field spot landing.
I was happy about the whole thing from two standpoints. First, I hadn’t had to deal with either a precautionary landing or a full fledged engine failure. Secondly, we had been given a ‘heads-up” that the number 2 cylinder would need to be overhauled soon. That gave us time to get funds together to ensure we could cover it.
While we had dodged the bullet from the safety standpoint, we obviously got hit from a financial one. We had just paid for the annual a few months ago, and the projected costs of the carburetor work were going to eat up most of the funds we had managed to save above that. That put us in the hole when it came to paying for the magnetos themselves and for the accompanying labor. To deal with it, I took out a loan to pay off my credit cards, pay for these airplane repairs, and generate enough spare cash to create a hedge against the cylinder overhaul costs but to perhaps improve either the avionics package or the interior of the airplane. I’ve looked at our finances for days, and that approach seemed to be the best solution.
I’m pushing our finances as hard as I can; and, truthfully, one more major upset will put us in the position of having to sell the airplane, whether we want to or not. That would probably knock me out of flying for a short while, but sometimes there are other things more important than keeping me in the air.
As we left Baytown and then the Taylor County airport behind us, we exited out from under the Class B rings and became clear to climb. Our course would take us just slightly east of north, so our correct cruise altitude was “odd plus five”. I planned to climb us up to three thousand five hundred for now. I shoved the throttle forward, and then engine responded, but roughly! Connie wasn’t saying anything, but I knew something wasn’t right. The outside air temperature had been in the seventies on the ground, so the first thing that popped into my mind was the possibility of carburetor icing. I pulled the carb heat full out and the engine seemed to smooth out a bit, so I left it for a minute or so and out it back in. The engine got rough again, so I applied carb heat again, and it smoothed out; when I reduced carb heat and the engine got rough again, I realized that carburetor icing was not the problem. My airplane’s engine has always run rich, so I started leaning the mixture back to see what would happen. Engine operation smoothed right out, so I continued the climb, checking my engine’s parameters, which all appeared normal. We leveled off at thirty-five hundred a few minutes later and everything seemed fine, so I climbed us up to fifty-five hundred where we leveled off for the rest of the flight.
We hit Branson the same weekend that a bunch of other Grumman owners were flying in. While we didn’t run in to them during our Saturday and Saturday night there, we did happen to be out at the airport and parked just off the departure end of the runway, when most of them were departing. I’ve long suspected that, while Cheetahs are not know for their stellar climb performance, ours was worse that the average Cheetah. While it was often impossible to tell whether any particular four-seat Grumman was a Traveler, Cheetah, or Tiger, some of them were marked with the model name. All in all, they were all airborne by the time they hit a third of the runway length. When we took off, we didn’t lift off until we had eaten up just under half the runway length. There were moments when I wondered if we were going to get off…
Returning home, at fifty-five hundred feet I could only get two-hundred feet per minute climb.
A few days after I got back, using the pilot’s operating handbook, the actual performance I had observed, and one of my old college airplane performance textbooks, I calculated we were 18 horsepower short of where we were supposed to be. I had assumed standard day conditions which, of course, we didn’t have; so the actual number was probably less than that. Still, it was confirming my feelings that something just wasn’t right. Our fuel consumption rate seemed to confirm that; it normally was 8.5 gallons per hour and on this flight it had been 10!
I called my mechanic and discussed what was going on. We had not really looked into the carburetor, and that made sense as a good place to start. So, he dug into it and found the throttle plate bushings were extremely worn (causing some internal leakage within the carburetor) and the accelerator pump had a hole in it, reducing overall gas flow to a trickle of its expected self.
Despite my mechanic’s prediction the airplane would accelerate much faster, I couldn’t sense any added speed down the runway when I lifted off. I climbed the bird up to thirty-five hundred feet and forty-five hundred feet on a couple of occasions, and climb performance didn’t seem to improve but did seem to hang in longer before falling off. At about five thousand feet, I was seeing about four hundred feet per minute. But I also noticed a pronounced engine roughness at full throttle, even as low as fifteen hundred feet. I took the airplane back with that complaint about two weeks later.
Bill thought the carburetor might be dumping too much gas in at full throttle, so he checked it. It seemed to be set correctly, so he did a run-up and noticed that the engine ran rough when running on the L mag, even though the mag drops where within limits. He checked the associated plugs and found one on the number 2 cylinder was oil-fouled. He cleaned it up and tried it again, and it oil-fouled almost immediately. Feeling that the problem might be in the magnetos, he took them apart and found that the left mag was about to fail due to some cracked parts. He also borescoped the number 2 cylinder and determined there was blow-by past the rings and on the intake valve side, but thought the cylinder had some more life in it before being overhauled. (He estimated 200-300 hours. We had only one cylinder that showed anything a bit off in compressions, and I didn’t think it was the #2.) He called and told me the mags were about to fail and would have had I flown it much longer before calling him in. We had dodged an “engine-failure bullet”, though the failure might have produced only a precautionary landing rather than a full off-field spot landing.
I was happy about the whole thing from two standpoints. First, I hadn’t had to deal with either a precautionary landing or a full fledged engine failure. Secondly, we had been given a ‘heads-up” that the number 2 cylinder would need to be overhauled soon. That gave us time to get funds together to ensure we could cover it.
While we had dodged the bullet from the safety standpoint, we obviously got hit from a financial one. We had just paid for the annual a few months ago, and the projected costs of the carburetor work were going to eat up most of the funds we had managed to save above that. That put us in the hole when it came to paying for the magnetos themselves and for the accompanying labor. To deal with it, I took out a loan to pay off my credit cards, pay for these airplane repairs, and generate enough spare cash to create a hedge against the cylinder overhaul costs but to perhaps improve either the avionics package or the interior of the airplane. I’ve looked at our finances for days, and that approach seemed to be the best solution.
I’m pushing our finances as hard as I can; and, truthfully, one more major upset will put us in the position of having to sell the airplane, whether we want to or not. That would probably knock me out of flying for a short while, but sometimes there are other things more important than keeping me in the air.
posted by Andy Foster at 6:28 AM
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