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#11
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Hi Marty
I read your post earlier today at work but was too busy to respond. Now I have time. When I read your report I was very suprised to read that all of your preliminary steps - after discovering the problem, did not even consider carb ice. I believe that carb ice is exactly what you had. In my part of the world the procedure for those symptoms is - Best Glide Find landing area Carb Heat Briefing Cause check Radio Act accordingly HTH Tony In article , "Marty from Sunny Florida" wrote: Hello everyone. The end of my story is this; We landed safely in the middle of the Florida Everglades and didn't get a single Alligator bite. Here's what happened; On Friday, April 29th, we took our Cessna 152 from Lantana, Florida to the center of the State for gas and start our trek south to Key West. The total journey is a little over 2 hours. Forty five minutes after filling with gas in Pahokee, we were just below Alligator Alley (highway 75). Our engine hiccupped. A few minutes later, it hiccupped again, this time losing a couple of hundred RPM. We were at 6,800 feet, strait and level flight running at 75% power (about 2350 RPM). The mixture had been leaned back about 30 minutes earlier, and none of the engine instruments had changed from the time we made our cruise altitude. As the hiccups got closer together engine power dropped off significantly, grabbing our total attention. My first move was pulling up on the yoke to maintain altitude. I trimmed to our plane's best glide of 60 kts When the sputtering became a constant rough drone, the engine still held some power, and we could see nothing but marsh. I though about the choice between ditching in green or brown muck, not sure where the biggest alligators live. There was absolutely no solid ground as far as the eye could see. Solemnly, I rolled the 'standby' frequency to 121.5 acknowledging the severity of our predicament. Acting on the premise that the engine could quit at any moment and our best option was behind us on highway I75, I started a very gentle 180 degree turn. Oil pressure was in the green. Oil temp was in the green. Mags were on BOTH. The fuel showed close to full (I had at least 18 gallons useable). My only immediate change was to push the mixture to full rich, which had no effect. When I touched the throttle to add power, the RPM dropped. Gently, I returned the throttle and the power evened out. The sky was clear, and when I got my pre-flight briefing, the temp was 26 and dew point 16. It was unseasonably cool and very dry for Florida. At altitude, I knew the air had almost no moisture, but on the way up, we did have a typical hazy layer. My next move was carb heat, even though there was absolutely no visible moisture. It did smooth out the roughness slightly, but did nothing for the power loss. The engine was dying, and the math was simple. Sink at 500 fpt, 6,800 feet gives me about 13 minutes and at 60 kts, I'd get about 15 statute miles. I knew I could make the highway without an engine. I've personally had experience looking for downed aircraft in the Florida swamp, and know how difficult it is to spot a small plane. We needed to let someone know our position and situation. We had the skill to find the closest airport but every moment was precious. ATC could save valuable minutes and that might make the difference. With this in mind, I hit the radio's flip-flop button and announced our tail number on the emergency frequency. The Controller was a true professional. He asked me a few questions and instructed me to "ident" before assigning a squawk code. The radio reception was not clear, which generated a stream of "say agains". This, of course added to the general stress of the situation. Efficiently, he ascertained our position and vectored me to the Dade-Collier airport, which is in the middle of nowhere. Ironically, so were we! The strip was 17 miles to our southwest, which is farther than a dead engine would take me. We had been heading due north to a safe landing point on I75 when ATC advised us to turn our backs on the hwy and return south. In my heart, we turned away from solid ground to face only swamp again. I decided to trust fate and the ATC controller as I asked the alligators to gift me the extra minutes of engine power needed to make the airport. Trimmed back to slow flight, we managed to barely maintain altitude. We arrived at the 10,500 foot runway with 3,200 feet of altitude and 120 kts of air speed. I figure I could have made 4 complete turns around the pattern and still land hot. I have never been so relieved in my entire life. On the ground, we taxied to an area near two other planes. Relieved and curious I did a runup and the engine gave a text book performance. Our cell phones didn't work so we called the FBO on the radio. We were invited into the small building nearby where there was a phone. There we learned that the other two planes had landed the day before with similar symptoms. I phoned my mechanic and relayed the story. He gave me some great advice and a definite suggestion about what caused the problem. We returned to the plane to follow my mechanics instructions. Another mechanic, who had come to pick up one of the other downed planes kindly offered to look at my engine. He pulled the cowl open, checked the cables on the throttle, carb heat and mixture. He sat in the 152 with me while I did a regular and then full-power run up. The engine showed great response to throttle, the mixture choked it and the carb heat performed as advertised. This qualified mechanic was planning to fly out in a plane that landed in the same condition as ours. They offered us a ride if we were not comfortable flying our 152. We had options. Now, we had to make a decision to take the ride or hop in our plane and head out. The logic was: someone at some point would fly our 152 out, and we would again need to fly this same plane at some point ourselves. If we waited, what would be different? A qualified mechanic not only said it was safe, but was flying out a plane in the same condition. We decided the problem had resolved itself. We would fly. After a lengthy check, we headed for the runway. I did a steep climb over the field, continued uphill after completing a long, slow circuit of the airport, and headed north with a 500 FPM climb. All the while, I knew I could glide back to the runway if needed. It was late to start our day in the Keys so we turned towards home. When We sighted I75, I knew I was home free. If there was trouble we were guaranteed a level spot to land. We made Lantana at full power with no sign of the earlier problem. I must say, I am impressed with the FAA system and the people who dedicate their careers to the safety of our skies. This system that trains and relies on the good judgment of the individual pilot also supports the decisions necessary in crisis. While part of the mandate of the FAA is to enforce the laws, a pilot's decisions are respected even when they are examined. I find great comfort in the FAA and the service it provides to general aviation. If our highways resembled our skies, perhaps the average driver would be less likely to knowingly break the law. Here's my question to this group. What caused the engine failure? More than one thought is welcome, but please explain your answer. I have one of two possibilities in my head, and invite any questions, advise, opinions, or wisdom. Warm regards from one very happy pilot. Marty -- Tony Roberts PP-ASEL VFR OTT Night Cessna 172H C-GICE |
#12
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On Wed, 04 May 2005 06:01:22 GMT, tony roberts
wrote: Hi Marty I read your post earlier today at work but was too busy to respond. Now I have time. When I read your report I was very suprised to read that all of your preliminary steps - after discovering the problem, did not even consider carb ice. I believe that carb ice is exactly what you had. In my part of the world the procedure for those symptoms is - Best Glide Find landing area Carb Heat Briefing Cause check Radio Act accordingly HTH Tony I think that everyone here is pretty much in agreement that carb ice is suspect numero uno here. But there is something that I teach my students to do is immediately pull the carb heat (and leave it on) while you are setting up for best glide and looking for a suitable landing site. It takes a tenth of a second to reach and pull that knob. The longer you wait to do this, the cooler the engine is getting and carb heat becomes less effective. Then after you have obtained best glide and you are heading for your landing site, then go through the troubleshooting and preparing for an emergency landing. Scott D To email remove spamcatcher's |
#13
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Yep, that was exactly my thinking. If the a/c were all from the same
field or stopped the same place for fuel, contamination would be a suspect... otherwise carb ice. Great lesson for those that have never experienced it. George Patterson wrote: Carb ice. The only two things that I can think of that can cause those symptoms in several aircraft at the same time are ice and fuel contamination. Fuel contamination doesn't go away after you land, |
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#15
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On 5/3/2005 14:58, Marty from Sunny Florida wrote:
Hello everyone. [ snip ] As the hiccups got closer together engine power dropped off significantly, grabbing our total attention. My first move was pulling up on the yoke to maintain altitude. I trimmed to our plane's best glide of 60 kts When the sputtering became a constant rough drone, the engine still held some power, and we could see nothing but marsh. I though about the choice between ditching in green or brown muck, not sure where the biggest alligators live. There was absolutely no solid ground as far as the eye could see. Solemnly, I rolled the 'standby' frequency to 121.5 acknowledging the severity of our predicament. First of all, I'm very happy that you were able to land safely. Since everyone else has dealt with the carb ice issue, I would like to ask about your position over the glades. Granted I don't have a lot of experience yet, but I've been taught (sternly) not to allow the airplane to get anywhere that it can't make a safe landing in the event of a power failure. From your description, it sounds like a total power failure would have left you with a marsh ditching and alligators. I realize there are some cases that you just can't account for, but it seems like there should have been a route that would not have been quite so perilous. It is not my intention to lecture (nor have I any desire to do so), but am wondering if this experience will change your mind about the routes you take in future flights. Whether or not carb ice was the issue, you still kept your cool and went through a very straight-forward thought process to determine the cause of the problem and maintain the safety of your flight. Very nice job and story! -- Mark Hansen, PP-ASEL, Instrument Student Sacramento, CA |
#16
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Mark Hansen wrote:
I realize there are some cases that you just can't account for, but it seems like there should have been a route that would not have been quite so perilous. You can go through the Miami class B. Good luck getting cleared through there in a VFR 150. You can go over the top of Miami class B (long way to climb in a 150, but possible). You can go east of the class B over the ocean, or you can go west of the class B over the swamp. |
#17
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Marty from Sunny Florida wrote:
The sky was clear, and when I got my pre-flight briefing, the temp was 26 and dew point 16. It was unseasonably cool and very dry for Florida. At altitude, I knew the air had almost no moisture, but on the way up, we did have a typical hazy layer. Temp 26 and dewpoint 16 puts you well outside the icing region on this chart: http://www.ez.org/carb_ice.htm The temperature at altitude was probably well below 26, but even so you seem to be pretty well outside the temperature / dewpoint danger zone. Nevertheless, I agree with the consensus that carb ice is the best explanation. I'm mystified that the chart doesn't confirm. Dave |
#18
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On 5/4/2005 08:20, Dave Butler wrote:
Marty from Sunny Florida wrote: The sky was clear, and when I got my pre-flight briefing, the temp was 26 and dew point 16. It was unseasonably cool and very dry for Florida. At altitude, I knew the air had almost no moisture, but on the way up, we did have a typical hazy layer. Temp 26 and dewpoint 16 puts you well outside the icing region on this chart: http://www.ez.org/carb_ice.htm I assumed the temperatures provided by the original poster were in centigrade. That puts the temp at 79 deg F and the dew point at 61 deg F. Assuming 2 deg C drop per thousand feet, that puts the temperature at 57 deg F and the dew point at 35 deg F. Very close to the blue "Icing at glide and cruise power" band. The temperature at altitude was probably well below 26, but even so you seem to be pretty well outside the temperature / dewpoint danger zone. Nevertheless, I agree with the consensus that carb ice is the best explanation. I'm mystified that the chart doesn't confirm. Dave -- Mark Hansen, PP-ASEL, Instrument Student Sacramento, CA |
#19
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On 5/4/2005 08:13, Dave Butler wrote:
Mark Hansen wrote: I realize there are some cases that you just can't account for, but it seems like there should have been a route that would not have been quite so perilous. You can go through the Miami class B. Good luck getting cleared through there in a VFR 150. You can go over the top of Miami class B (long way to climb in a 150, but possible). You can go east of the class B over the ocean, or you can go west of the class B over the swamp. Are you suggesting that it is reasonable to fly in such a case simply because it's difficult (or impossible) to find a safer route? I guess everyone will have their own personal safety margins, but if I was unable to come up with a way to safely make the flight, I would not fly. Perhaps this is simply due to my lack of experience. -- Mark Hansen, PP-ASEL, Instrument Student Sacramento, CA |
#20
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I"m not sure I agree with you regarding carb ice. While it may not have
been your problem, I've had carb ice in the J-3 that resulted in more than just a drop in RPM, the engine was doing next to nothing. Each time I've gotten carb ice it has been with not visible moisture. I think the visible moisture thing is just an old wive's tale. There is no need for visible moisture to get carb ice. Does the C-152 have a fuel filter? In my Mooney I have a couple screens but no "filter" per say. I guess the difference is that the screens (in theory) are for larger stuff and not as likely to clog. |
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