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#1
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Mooney Engine Problem in Flight - Advise
This is a bit long winded but I'm looking for qualified opinions as to what
might have happed to an almost total loss of power while in cruise flight in my Mooney M20F. Here is the story of what happened: I was flying from Turlock (south of Modesto) to Petaluma (north of San Francisco) on a Saturday. Weather was strange with a thick mist and fog layer from about 500 feet to 2000 feet. I was VFR on top and there were no holes anywhere through the fog/clouds/mist. Prior to the flight, I sumped the wings with no indication of any water. I did a normal run up and there were no issues at all. I was running on the left tank which is what I had run on for the last 1/2 of the flight the night before. Left tank had about 20 gallons right tank about 30. Take off was no issue and full power was available with a good sounding engine. I found a hole in the clouds and climbed to 4,500 on a heading direct to Petaluma. About eight minutes into the flight (from take off), suddenly but not sudden like a switch or electrical problem I would guess power output dropped to around 30% with a decent engine vibration. It felt and acted as if two sparkplug wires were simultaneously pulled from the plugs. I noticed the EGT that I had leaned to 1320 F was now down to below 1000 F. I checked the mags and there was no difference in operation between both, 1 or 2. I pushed the throttle in full with no effect. I switched tanks to the right wing with no effect. I turned on the boost pump with no effect. I opened the power boost which bypasses the air filter which resulted in a tiny bit of improvement maybe getting me up to 35% power. I moved the mixture in full rich and it smoothed out considerably and I would guess power output moved up to say 45%. My speed leveled off at around 124 knots from the 151 it was just prior. I was able to hold 4,500 feet. EGT rose only about to 1100 F. I contacted NorCal and advised them of my situation. They were great and offered vectors to Modesto that I was right on top of according to the GPS. I advised them that it was totally socked in fog that spread about 20 miles in all directions. After about 30 seconds later I slowly moved the mixture out and it began running extremely rough with no increase in EGT so I pushed it back in scared that I would make it worse and loose my 45% power output. NorCal asked what I wanted to do and as airspeed was being held, it was producing about 45% power and I was holding altitude I told them I would forge ahead. I felt this was less risky than dropping through the fog layer into 3 miles of mist visibility with engine problems trying to find a runway with towers up around 500 feet in the area. Time is strange and I'm guessing after about 5 minutes of this, I felt the plane pull forward like there was a significant power increase and I noticed the EGT move up to 1190 F. I leaned it a little and EGT went up to 1200 F max and quickly began to run rough so I slid it back in to full rich. After about 3 more minutes I would say the power seemed to up around 60% and I tried leaning again. This time it leaned like always rising to a maximum of about 1410 F before running rough so I backed off to run around 1310 F - normal operation. The whole event from the start of something being wrong to full power being restored was I would say around 10 minutes. Maybe a little less. From that point on it was like nothing was wrong. Remaining 30 minutes of the flight went without a hitch and the engine responded just like it should and always has. I can only think that there was some water stuck somewhere in the wing behind one of the baffles and the engine just had to work through it. I can't think of anything else that could have caused this behavior. The following day I went out and did 10 sumps of each tank and the center sump. None showed any sign of water. If it was a bad mag I would have expected to loose the engine completely when I went to mag 1 or mag 2 but I didn't. Only thing I can come up with is either water in the tank or an obstruction in the line. The engine problem would not have been so critical if I wasn't VFR on top. Without an engine and VFR on top you have very little options. Thanks for your opinions and advise. Please post any responses here. Mooney M20F PS. Other info is that fuel consumption was normal and I'm at just now at 6 qts of oil remaining after 16.5 hours since last oil change. So that works out to be about 11.8 hours per qt. No other indications of problems. Except of course the oil and gas dripping out of the plenum drain after stopping the engine. Engine has about 80 hours since LMOH and has worked perfectly. |
#2
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"Paul Smedshammer" wrote in message . com... This is a bit long winded but I'm looking for qualified opinions as to what might have happed to an almost total loss of power while in cruise flight in my Mooney M20F. Here is the story of what happened: I was flying from Turlock (south of Modesto) to Petaluma (north of San Francisco) on a Saturday. Weather was strange with a thick mist and fog layer from about 500 feet to 2000 feet. I was VFR on top and there were no holes anywhere through the fog/clouds/mist. Prior to the flight, I sumped the wings with no indication of any water. I did a normal run up and there were no issues at all. I was running on the left tank which is what I had run on for the last 1/2 of the flight the night before. Left tank had about 20 gallons right tank about 30. Take off was no issue and full power was available with a good sounding engine. I found a hole in the clouds and climbed to 4,500 on a heading direct to Petaluma. About eight minutes into the flight (from take off), suddenly but not sudden like a switch or electrical problem I would guess power output dropped to around 30% with a decent engine vibration. It felt and acted as if two sparkplug wires were simultaneously pulled from the plugs. I noticed the EGT that I had leaned to 1320 F was now down to below 1000 F. I checked the mags and there was no difference in operation between both, 1 or 2. I pushed the throttle in full with no effect. I switched tanks to the right wing with no effect. I turned on the boost pump with no effect. I opened the power boost which bypasses the air filter which resulted in a tiny bit of improvement maybe getting me up to 35% power. I moved the mixture in full rich and it smoothed out considerably and I would guess power output moved up to say 45%. My speed leveled off at around 124 knots from the 151 it was just prior. I was able to hold 4,500 feet. EGT rose only about to 1100 F. I contacted NorCal and advised them of my situation. They were great and offered vectors to Modesto that I was right on top of according to the GPS. I advised them that it was totally socked in fog that spread about 20 miles in all directions. After about 30 seconds later I slowly moved the mixture out and it began running extremely rough with no increase in EGT so I pushed it back in scared that I would make it worse and loose my 45% power output. NorCal asked what I wanted to do and as airspeed was being held, it was producing about 45% power and I was holding altitude I told them I would forge ahead. I felt this was less risky than dropping through the fog layer into 3 miles of mist visibility with engine problems trying to find a runway with towers up around 500 feet in the area. Time is strange and I'm guessing after about 5 minutes of this, I felt the plane pull forward like there was a significant power increase and I noticed the EGT move up to 1190 F. I leaned it a little and EGT went up to 1200 F max and quickly began to run rough so I slid it back in to full rich. After about 3 more minutes I would say the power seemed to up around 60% and I tried leaning again. This time it leaned like always rising to a maximum of about 1410 F before running rough so I backed off to run around 1310 F - normal operation. The whole event from the start of something being wrong to full power being restored was I would say around 10 minutes. Maybe a little less. From that point on it was like nothing was wrong. Remaining 30 minutes of the flight went without a hitch and the engine responded just like it should and always has. I can only think that there was some water stuck somewhere in the wing behind one of the baffles and the engine just had to work through it. I can't think of anything else that could have caused this behavior. The following day I went out and did 10 sumps of each tank and the center sump. None showed any sign of water. If it was a bad mag I would have expected to loose the engine completely when I went to mag 1 or mag 2 but I didn't. Only thing I can come up with is either water in the tank or an obstruction in the line. The engine problem would not have been so critical if I wasn't VFR on top. Without an engine and VFR on top you have very little options. Thanks for your opinions and advise. Please post any responses here. Mooney M20F PS. Other info is that fuel consumption was normal and I'm at just now at 6 qts of oil remaining after 16.5 hours since last oil change. So that works out to be about 11.8 hours per qt. No other indications of problems. Except of course the oil and gas dripping out of the plenum drain after stopping the engine. Engine has about 80 hours since LMOH and has worked perfectly. Sounds like water to me. My Mooney M20J sat outside for a year. The only way to completely remove the water in the wings was to raise or lower the wings. I did this by positioning one of the main wheels over a drain in the pavement, which gave me about a 3 degree bank. Much more water could be removed this way. I supose you could use a small jack on one side with better results. I also stuck rubber pads (rubber door mats) over the fuel caps, to keep rain from running past the crummy (even when new) rubber fuel cap seals when tied down. Water problem went away when I got a hangar. Karl "Curator" N185KG |
#3
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Definitely sounds like indigestion. Either water (it's tough to get it
all out in a Mooney) or some particle that eventually made it through the injectors. |
#4
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#5
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Paul Smedshammer wrote: This is a bit long winded but I'm looking for qualified opinions as to what might have happed to an almost total loss of power while in cruise flight in my Mooney M20F. Here is the story of what happened: Almost sounds like induction icing. |
#6
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In article . com, "Grumman 236" wrote:
Paul Smedshammer wrote: This is a bit long winded but I'm looking for qualified opinions as to what might have happed to an almost total loss of power while in cruise flight in my Mooney M20F. Here is the story of what happened: Almost sounds like induction icing. A couple of folks have mentioned induction icing. Being a relatively new pilot to the Mooney and more specifically fuel injection, I wasn't aware that icing was a big problem in the fuel injection engines. There is no "carb. heat" as there is no carburetor. Maybe somebody can elaborate and educate me on icing in the induction system and what you can do to avoid it. Temps above the fog layer which I was 2,500 feet above were in the 60's so I didn't figure icing could have been a factor. |
#7
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#9
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"zatatime" wrote in message ... On Mon, 13 Dec 2004 16:44:33 GMT, (Paul Smedshammer) wrote: A couple of folks have mentioned induction icing. Being a relatively new pilot to the Mooney and more specifically fuel injection, I wasn't aware that icing was a big problem in the fuel injection engines. There is no "carb. heat" as there is no carburetor. Maybe somebody can elaborate and educate me on icing in the induction system and what you can do to avoid it. Temps above the fog layer which I was 2,500 feet above were in the 60's so I didn't figure icing could have been a factor. I think this is the correct "guess." Induction icing can occur in the 60 degree range without a problem if you have the right conditions (i.e. moisture, which you had alot of). In your original post you stated you put on an alternate air source of some sort to bypass the air filter. Check with your mechanic if this gives heated air to the mixture. If so this is the equivalent of carb heat, and could be how the problem resolved itself. If not, check to see how to provide warm air to the induction system. Even if you've got to make a modification (install something), it'll be worth it. HTH. z You can't get induction icing in a fuel injected engine with temps in the 60s regardless of how much moisture is present. Mike MU-2 |
#10
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