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#1
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Mooney Engine Problems in Flight
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 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. Giant snip It sounds almost like conditions were perfect for induction ice, but is that possible with this type of injection? Is there any provision for heat, or just unheated alternate air? This, from a definite unqualified person. Me. g -- Jim in NC |
#3
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VFR on top, not good if you and the plane are not capable of IFR flight.
Did the forcast call for any broken or scattered conditions along your route of flight, if so where?? Water in the fuel system can lead to freezing in the fuel line as you gain altitude. The weather report would give you the freezing level. This can of course block and/or restict the fuel flow. But, second guessing the problem is not too smart, I strongly suggest you have a shop check it out, maybe a fuel pump was sucking air from a loose fitting, etc. Have it checked out, and watch out for Mt. Diablo. Just remember, always have options: Clyde "Paul Smedshammer" wrote in message news 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. |
#4
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In article , "Morgans" 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. Giant snip It sounds almost like conditions were perfect for induction ice, but is that possible with this type of injection? Is there any provision for heat, or just unheated alternate air? This, from a definite unqualified person. Me. g The Mooney M20F has a fuel injection system so there is no carburetor nor 'carb heat'. I'm open to anything that could have caused this. Ice is a definite possibility in the fuel system. It hadn't rained but the overnight stay at the airport I left from had the most intense ground fog I have ever experienced. I would say there was 50 foot visibility on the ground that lasted a good 10 hours. I was thinking this could have caused some condensation to pool water on the inside of fuel tanks. Maybe after flying out, that condensation shook loose from the walls and pooled up and got sucked in. That being said, I was well above moisture and it was over 65 degrees F at the 4,500 feet I was at. The weather breifer made no mention of icing conditions and I didn't see any on the DUATs reports. I was VFR on top for the 30 miles that overcast was spread. This really opened my eyes as this problem happed just about 8 minutes into the 30 miles. It couldn't have happened at a worse time. I was very lucky I had the altitude and that it cleared up and normal power was restored. If the problem persisted, I would have definitely bent the plane up as a minimum and at the worst been killed and possibly cause bad results to folks on the ground. I definitely have a greater respect for VFR on top. Paul |
#5
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"Paul Smedshammer" wrote The Mooney M20F has a fuel injection system so there is no carburetor nor 'carb heat'. Paul Right, I know it is fuel injected, but it is a "throttle body" type, rather than individual injectors for each cylinder, isn't it? It seems to me that if it is this type, a possibility of a temperature drop from evaporating fuel could still open up an opportunity for water vapor in the air to freeze, in the right conditions. -- Jim in NC |
#6
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#7
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"Ron Rosenfeld" wrote: It sure sounds like a problem with fuel flow. Wouldn't a fuel restriction make the EGT go up? -- Dan C-172RG at BFM |
#8
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On Mon, 13 Dec 2004 07:42:08 -0600, "Dan Luke" wrote:
"Ron Rosenfeld" wrote: It sure sounds like a problem with fuel flow. Wouldn't a fuel restriction make the EGT go up? If you lean your engine until it starts to run rough, what happens (both to TIT as well as to the individual EGT's), is that the EGT initially rises, then it reaches a peak and begins to fall. So what happens to the EGT will depend on where you are on that curve, when the engine begins to run rough. I have had problems, over the years, with clogged injector; clogged fuel line; and clogged fuel servo. In all of those instances, the EGT for the affected cylinder(s) went down when engine roughness was noted. Except for the fuel servo when the problem became evident on takeoff and I was concentrating on landing, rather than looking at EGT's. Ron (EPM) (N5843Q, Mooney M20E) (CP, ASEL, ASES, IA) |
#9
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#10
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In article , "Morgans" wrote:
"Paul Smedshammer" wrote The Mooney M20F has a fuel injection system so there is no carburetor nor 'carb heat'. Paul Right, I know it is fuel injected, but it is a "throttle body" type, rather than individual injectors for each cylinder, isn't it? It seems to me that if it is this type, a possibility of a temperature drop from evaporating fuel could still open up an opportunity for water vapor in the air to freeze, in the right conditions. The IO-360A1A has individual injectors to for each cylinder. However, I'm still learning about the potential for induction icing to occur and I think you are right that this is a definite possibility. But as somebody mentioned in another post, if induction icing were the cause I should have seen a rise in the EGT as the fuel flow became restricted instead of a sudden drop from 1310 to under 1000 F. The most plausible cause that many have suggested so far is that there was water mixed in with the fuel. When I enriched the mixture it let a larger volume of the fuel/water mixture in which resulted in a slightly smoother and more powerfully running engine. Which would also account for the lower EGT. Then as this fuel/water mixture worked its way through, normal operation was restored when the fuel/water mixture returned to just fuel. I really hope this was the cause but I'm still open for it being something else that I need to be aware of. I still get sick thinking about this happening on climb out with a broken cloud and fog deck at 800 feet. As it took about 8 minutes to clear at full throttle in cruise there is no way it would have cleared during the climb out. And what is worse, if it was water in the fuel, I could have sucked in a full slug of water killing the engine completely. This was a serious learning experience for me. Just glad I'm around to apply it. Paul |
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